essay on what is climate change

Climate Change Essay for Students and Children

500+ words climate change essay.

Climate change refers to the change in the environmental conditions of the earth. This happens due to many internal and external factors. The climatic change has become a global concern over the last few decades. Besides, these climatic changes affect life on the earth in various ways. These climatic changes are having various impacts on the ecosystem and ecology. Due to these changes, a number of species of plants and animals have gone extinct.

When Did it Start?

The climate started changing a long time ago due to human activities but we came to know about it in the last century. During the last century, we started noticing the climatic change and its effect on human life. We started researching on climate change and came to know that the earth temperature is rising due to a phenomenon called the greenhouse effect. The warming up of earth surface causes many ozone depletion, affect our agriculture , water supply, transportation, and several other problems.

Reason Of Climate Change

Although there are hundreds of reason for the climatic change we are only going to discuss the natural and manmade (human) reasons.

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Natural Reasons

These include volcanic eruption , solar radiation, tectonic plate movement, orbital variations. Due to these activities, the geographical condition of an area become quite harmful for life to survive. Also, these activities raise the temperature of the earth to a great extent causing an imbalance in nature.

Human Reasons

Man due to his need and greed has done many activities that not only harm the environment but himself too. Many plant and animal species go extinct due to human activity. Human activities that harm the climate include deforestation, using fossil fuel , industrial waste , a different type of pollution and many more. All these things damage the climate and ecosystem very badly. And many species of animals and birds got extinct or on a verge of extinction due to hunting.

Effects Of Climatic Change

These climatic changes have a negative impact on the environment. The ocean level is rising, glaciers are melting, CO2 in the air is increasing, forest and wildlife are declining, and water life is also getting disturbed due to climatic changes. Apart from that, it is calculated that if this change keeps on going then many species of plants and animals will get extinct. And there will be a heavy loss to the environment.

What will be Future?

If we do not do anything and things continue to go on like right now then a day in future will come when humans will become extinct from the surface of the earth. But instead of neglecting these problems we start acting on then we can save the earth and our future.

Although humans mistake has caused great damage to the climate and ecosystem. But, it is not late to start again and try to undo what we have done until now to damage the environment. And if every human start contributing to the environment then we can be sure of our existence in the future.

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What Is Climate Change?

Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates. These changes have a broad range of observed effects that are synonymous with the term.

Changes observed in Earth’s climate since the mid-20th century are driven by human activities, particularly fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere, raising Earth’s average surface temperature. Natural processes, which have been overwhelmed by human activities, can also contribute to climate change, including internal variability (e.g., cyclical ocean patterns like El Niño, La Niña and the Pacific Decadal Oscillation) and external forcings (e.g., volcanic activity, changes in the Sun’s energy output , variations in Earth’s orbit ).

Scientists use observations from the ground, air, and space, along with computer models , to monitor and study past, present, and future climate change. Climate data records provide evidence of climate change key indicators, such as global land and ocean temperature increases; rising sea levels; ice loss at Earth’s poles and in mountain glaciers; frequency and severity changes in extreme weather such as hurricanes, heatwaves, wildfires, droughts, floods, and precipitation; and cloud and vegetation cover changes.

“Climate change” and “global warming” are often used interchangeably but have distinct meanings. Similarly, the terms "weather" and "climate" are sometimes confused, though they refer to events with broadly different spatial- and timescales.

What Is Global Warming?

Global warming is the long-term heating of Earth’s surface observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere. This term is not interchangeable with the term "climate change."

Since the pre-industrial period, human activities are estimated to have increased Earth’s global average temperature by about 1 degree Celsius (1.8 degrees Fahrenheit), a number that is currently increasing by more than 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade. The current warming trend is unequivocally the result of human activity since the 1950s and is proceeding at an unprecedented rate over millennia.

Weather vs. Climate

“If you don’t like the weather in New England, just wait a few minutes.” - Mark Twain

Weather refers to atmospheric conditions that occur locally over short periods of time—from minutes to hours or days. Familiar examples include rain, snow, clouds, winds, floods, or thunderstorms.

Climate, on the other hand, refers to the long-term (usually at least 30 years) regional or even global average of temperature, humidity, and rainfall patterns over seasons, years, or decades.

Find Out More: A Guide to NASA’s Global Climate Change Website

This website provides a high-level overview of some of the known causes, effects and indications of global climate change:

Evidence. Brief descriptions of some of the key scientific observations that our planet is undergoing abrupt climate change.

Causes. A concise discussion of the primary climate change causes on our planet.

Effects. A look at some of the likely future effects of climate change, including U.S. regional effects.

Vital Signs. Graphs and animated time series showing real-time climate change data, including atmospheric carbon dioxide, global temperature, sea ice extent, and ice sheet volume.

Earth Minute. This fun video series explains various Earth science topics, including some climate change topics.

Other NASA Resources

Goddard Scientific Visualization Studio. An extensive collection of animated climate change and Earth science visualizations.

Sea Level Change Portal. NASA's portal for an in-depth look at the science behind sea level change.

NASA’s Earth Observatory. Satellite imagery, feature articles and scientific information about our home planet, with a focus on Earth’s climate and environmental change.

Header image is of Apusiaajik Glacier, and was taken near Kulusuk, Greenland, on Aug. 26, 2018, during NASA's Oceans Melting Greenland (OMG) field operations. Learn more here . Credit: NASA/JPL-Caltech

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What is climate change and why does it matter?

Climate change is the defining issue of our time . We have reached a pivotal moment in deciding our planet's future.

Find out what climate change is, why it matters and what it could mean for our collective future.

What are weather, climate and climate change?

Weather refers to atmospheric conditions, such as rain or snow, happening in a place at a specific moment in time. Climate is how much, on average, a type of weather will occur over a longer period.

Dr Joeri Rogelj is a climate scientist at Imperial College London's Grantham Institute who has contributed to and led several major climate change assessments. He explains, 'Climate change is how the characteristics of the weather we experience in a certain place change.

'It can get hotter or wetter on average or have more concentrated rain in a short period, but then get longer dry periods. All of that can be a result of climate change.'

Global warming is a term used interchangeably with climate change, although the latter is preferred because the warming atmosphere and oceans are just some of the effects we see.

'It's not just about temperature. Places are also becoming wetter or drier, and in some the seasons are moving. Most importantly, in a few regions and seasons, it may actually at times be cooler than we're used to. That's confusing if you just talk about global warming.'

This is Typhoon Utor, which affected the Philippines and China in 2013. It caused considerable damage and loss of life. Climate change influences most weather events, including tropical storms and hurricanes. © NASA Goddard Space Flight Center via Flickr ( CC BY 2.0 )

Causes of climate change

The main driver of current climate change is the emission of greenhouse gases, most importantly carbon dioxide and methane . These are primarily released when fossil fuels are burnt. Meat and dairy production, producing cement and some industrial processes, such as the production and use of fertilisers, also emit greenhouse gases.

Greenhouse gases trap heat in our atmosphere. Since the mid-nineteenth century , the world has emitted over 2.2 trillion tonnes of carbon dioxide.

Joeri explains, 'Energy from the Sun falls on our planet and normally gets reflected back as infrared radiation. But instead of escaping back out into space, this radiation gets absorbed by molecules of greenhouse gases, which then emit them in all directions.'

This process causes more heat to be kept near Earth's surface, warming our world.

How do we know climate is changing?

There are measuring stations all around the world that keep track of air and sea temperature. From these measurements it's clear that temperatures are rising.

'There are many more indicators that tell us that the Earth is warming. For example, on a warming planet we would expect polar ice caps and glaciers to melt. It is clearly observed that those are melting,' explains Joeri.

This image of an iceberg in McMurdo Sound was captured in 2017 as part of NASA's Operation IceBridge. This is an ongoing airborne mission to monitor changes in polar ice. © NASA Goddard Space Flight Center via Flickr ( CC BY 2.0 )

We know that greenhouse gases are causing change. Thanks to studies that look at how carbon dioxide absorbs infrared radiation, for example, there is a scientific understanding of how the planet would warm as a result of emissions. This has allowed climate scientists to discount the theory that global warming is being caused by an increase in the Sun's intensity, for example.

It's also known that greenhouse gases are primarily emitted by fossil fuel combustion.

'To burn carbon and produce carbon dioxide, you need oxygen. The amount of oxygen that is in the atmosphere is reducing at exactly the right amount for the increase in carbon dioxide to be caused by combusting fossil fuels,' explains Joeri.

There is additional evidence in the ratios of different types of carbon. Fossil fuels are, essentially, ancient plants . Plants now and in the past preferentially take up carbon-12. In normal conditions, the ratio between carbon-12 and carbon-13 is constant.

'What we can see is that the ratio of carbon-13 in our atmosphere is going down at exactly the rate you would predict if the carbon dioxide increase was due to burning fossil fuels.'

Scientists predict that climate change will cause extreme weather events such as wildfires, floods and hurricanes to become worse ©  Quarrie Photography via Flickr ( CC BY-NC-ND 2.0 )

Effects of climate change

Climate change does not have the same effects everywhere. The planet is generally getting hotter, but some regions and seasons can at times be temporarily cooler. Some places will see drawn-out seasons, while others may experience concentrated bursts of extreme weather.

Extreme weather events - such as hurricanes, floods, heatwaves , drought and  wildfires  - are predicted to become more intense and frequent.

'Pretty much any weather event is influenced by climate change. As scientists we can estimate how much climate change has made a certain event more likely or more intense than it would have been without climate change,' explains Joeri.

When the world warms, ice melts. Arctic sea ice could disappear entirely in a warming world, and Greenland and Antarctica's ice sheets could be destabilised. This would result in large sections melting, which would add more liquid to the ocean. 

Sea level rise caused by climate change is a threat to low lying islands such as Panama's idyllic San Blas Islands, 49 of which are inhabited © Marc Veraart via Flickr ( CC BY-ND 2.0 )

Ice also reflects the Sun's energy, so without ice, more heat is absorbed by the ocean . Water expands as it warms - this is known as thermal expansion. This effect means that the ocean takes up more space, causing sea levels to rise. Even with rapid emission cuts, sea levels are expected to rise by around 26 to 53 centimetres by 2100.

Along with melting ice sheets and glaciers, rising global temperatures could cause rainforests to die and widespread species extinctions.

The effects of climate change on us

How climate change will affect you depends on who you are and where you live.

Around 190 million people currently live in areas that, due to rising sea levels, are expected to be under high tide levels by 2100. This could cause a massive displacement of populations. Low lying atoll nations such as Tuvalu and the Maldives are incredibly vulnerable to this change and could be lost to the sea.

Hundreds of millions of people rely on seafood as their main source of protein. Warming and more acidic waters could destroy marine food chains by affecting their base, such as krill or coral reefs .

Longer-lasting drought could devastate crops, threating food security. Reservoirs drying up , as well as the loss of glaciers, could make drinking water scarce. 

Pasterze Glacier is estimated to be receding at a rate of 10 metres per year. A sign shows where the glacier lay in 1995, with the ice having since dramatically retreated up the valley. ©  H Raab via Flickr ( CC BY-NC-ND 2.0 )

Increased precipitation can cause deadly flooding, as well as lowering indoor air quality. This could affect our health as dampness benefits moulds and fungi.

Around four billion people live in urban areas, and by 2050 this will have risen to an estimated 6.7 billion.

City dwellers are not exempt from climate change's effects. Urban populations usually rely on rural areas for inputs such as food and water. If climate change disrupts these important connections, it could heavily affect those in urban areas.

Natural disasters impact poor and vulnerable populations disproportionately hard and clearly expose the consequences of ignoring social inequalities . With extreme weather increasing, these populations face a heightened level of risk.

For example, the urban heat island effect amplifies the effects of temperature extremes in cities. Those unable to afford to buy and run air conditioning may find their health compromised.

The hazards of climate change also do  disproportionate harm to women and girls .

Joeri says, 'We don't know what will happen when, exactly. It's really hard to anticipate, particularly for populations that are already on the edge every year.'

People are also seeing climate change impact their mental health, experiencing a phenomenon known as eco-anxiety . 

Differences in wealth, ethnicity and health are just some of the inequalities that could determine a person's vulnerability to the effects of climate change © Kompas/Hendra A Setyawan via World Meteorological Organization Flickr ( CC BY-NC-ND 2.0 )

How does climate change affect biodiversity?

The natural world is delicately balanced . No species - including ours - is completely independent of all others. A 2019 report confirmed that over one million animal and plant species are now at risk of extinction as a result of human activities.

In the UK, an analysis of over 700 species has shown that more than 80% of trends between 1976 and 2005 indicate seasonal events are happening earlier. Differing rates of change could mean that species' lives are no longer synchronised with those they rely on.

Many plants are flowering earlier. Migrating birds arrive earlier, leave later and some even are getting smaller . Butterflies are emerging earlier . Birds and amphibians are laying their eggs earlier in the year. Some species are moving into new areas, such as kelps which form vital marine habitats.

Seaweeds are important for many reasons . They act as vital habitats. Some also help protect coastlines from erosion.

Insects are one of the most vulnerable groups, with less ability than mammals or birds to escape warmer temperatures. Loss of insects, which are a primary food source for many animals, a key pollinator of plants and whose numbers are already plummeting , could cause the ecosystem to collapse.

In aquatic ecosystems, activities to mitigate the side effects of climate change, such as building hard flood defences, can have negative effects. As sea levels rise, sea walls reduce the space for intertidal ecosystems. A rising sea could also damage important coastal habitats like sand dunes and cliffs.

Joeri says, 'The ocean looks homogenous, but it also experiences variations. There are ocean heatwaves, where if a particularly warm mass of water comes to an area like coral reefs, it induces loss and mass dieback.'

The loss of Arctic sea ice takes away a key habitat from animals including polar bears, seals and walruses. The ice is now declining at a rate of more than 12% per decade .

Climate change is just one of the stressors currently impacting nature. Sea use, invasive species, pollution and the exploitation of organisms are all factors in the threat to nature. Without drastic changes , it's expected that there will be devastating changes in biodiversity and ecosystems.

Find out more about the link between climate change and the biodiversity crisis . 

A warming planet and melting ice threatens the survival of iconic animals such as polar bears © Gary Kramer/USFWS via U.S. Fish and Wildlife Service Flick r ( CC BY 2.0 )

Is there any hope for the future?

Climate change has been a known problem for around 30 years. Starting to fix it earlier might have made this daunting task much easier.

Joeri says, 'We definitely know how to reduce emissions to a significant degree. We are seeing more impacts of climate change, but we can also see a heightened interest and concern in the general public.

'Ultimately, reducing emissions is really an issue of public and political will.'

By understanding more about the planet, such as by studying the poles, scientists are able to estimate the consequences climate change will have © NASA Goddard Space Flight Center via Flickr ( CC BY 2.0 )

Over the past decades, scientists have estimated the potential impacts of the planet's average temperature rising by different amounts.

'Based on that information, governments have come together and decided that they don't want to exceed a 2°C rise. They want to be well below that and pursue efforts to make it as close as possible to 1.5 °C.'

The difference in outcomes between 1.5 and 2°C are considerable. The impacts are the difference of 70% or 99% of coral reefs dying or a summer free of Arctic sea ice once every 100 or 10 years.

Scientists have determined how much carbon dioxide can still be emitted before this temperature rise limit will be exceeded. This is called the carbon budget and it's relatively small.

Joeri says, 'It's currently 420 to 580 billion tonnes of carbon dioxide for having a two-in-three or a one-in-two chance of limiting warming to 1.5°C, starting to count in 2018.

'Today we are roughly emitting 42 billion tonnes a year. So, if you start today and are going to net-zero emissions , if you want a one-in-two chance, we should there by around mid-century.

'These numbers define the geophysical requirement. Scientists then use engineering and economic models to understand how we can transform society to stay within that emission limit.'

There are many ways that you can help the planet . One way is by reducing the amount of meat and dairy you eat. © Theo Stikkelman via Flickr ( CC BY 2.0 )

This transformation could include changes such as increasing the share of energy produced by renewables , changing the way food is produced , changing our diets to have a lower carbon footprint and changing the way we build houses and design cities .

Moving to net-zero emissions will not be a perfectly co-ordinated transition . It will take some countries to lead and show the world that moving to this new way of living and functioning is both possible and beneficial for other sustainability objectives, such as public health and food security.

But on whether we'll ever see a change for the better, Joeri says he's hopeful.

'Preferably we would have started 25 or 30 years ago, but I will take any year at which we start declining steadily towards net-zero.'

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Human activity affects global surface temperatures by changing Earth ’s radiative balance—the “give and take” between what comes in during the day and what Earth emits at night. Increases in greenhouse gases —i.e., trace gases such as carbon dioxide and methane that absorb heat energy emitted from Earth’s surface and reradiate it back—generated by industry and transportation cause the atmosphere to retain more heat, which increases temperatures and alters precipitation patterns.

Global warming, the phenomenon of increasing average air temperatures near Earth’s surface over the past one to two centuries, happens mostly in the troposphere , the lowest level of the atmosphere, which extends from Earth’s surface up to a height of 6–11 miles. This layer contains most of Earth’s clouds and is where living things and their habitats and weather primarily occur.

Continued global warming is expected to impact everything from energy use to water availability to crop productivity throughout the world. Poor countries and communities with limited abilities to adapt to these changes are expected to suffer disproportionately. Global warming is already being associated with increases in the incidence of severe and extreme weather, heavy flooding , and wildfires —phenomena that threaten homes, dams, transportation networks, and other facets of human infrastructure. Learn more about how the IPCC’s Sixth Assessment Report, released in 2021, describes the social impacts of global warming.

Polar bears live in the Arctic , where they use the region’s ice floes as they hunt seals and other marine mammals . Temperature increases related to global warming have been the most pronounced at the poles, where they often make the difference between frozen and melted ice. Polar bears rely on small gaps in the ice to hunt their prey. As these gaps widen because of continued melting, prey capture has become more challenging for these animals.

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global warming , the phenomenon of increasing average air temperatures near the surface of Earth over the past one to two centuries. Climate scientists have since the mid-20th century gathered detailed observations of various weather phenomena (such as temperatures, precipitation , and storms) and of related influences on climate (such as ocean currents and the atmosphere’s chemical composition). These data indicate that Earth’s climate has changed over almost every conceivable timescale since the beginning of geologic time and that human activities since at least the beginning of the Industrial Revolution have a growing influence over the pace and extent of present-day climate change .

Giving voice to a growing conviction of most of the scientific community , the Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP). The IPCC’s Sixth Assessment Report (AR6), published in 2021, noted that the best estimate of the increase in global average surface temperature between 1850 and 2019 was 1.07 °C (1.9 °F). An IPCC special report produced in 2018 noted that human beings and their activities have been responsible for a worldwide average temperature increase between 0.8 and 1.2 °C (1.4 and 2.2 °F) since preindustrial times, and most of the warming over the second half of the 20th century could be attributed to human activities.

AR6 produced a series of global climate predictions based on modeling five greenhouse gas emission scenarios that accounted for future emissions, mitigation (severity reduction) measures, and uncertainties in the model projections. Some of the main uncertainties include the precise role of feedback processes and the impacts of industrial pollutants known as aerosols , which may offset some warming. The lowest-emissions scenario, which assumed steep cuts in greenhouse gas emissions beginning in 2015, predicted that the global mean surface temperature would increase between 1.0 and 1.8 °C (1.8 and 3.2 °F) by 2100 relative to the 1850–1900 average. This range stood in stark contrast to the highest-emissions scenario, which predicted that the mean surface temperature would rise between 3.3 and 5.7 °C (5.9 and 10.2 °F) by 2100 based on the assumption that greenhouse gas emissions would continue to increase throughout the 21st century. The intermediate-emissions scenario, which assumed that emissions would stabilize by 2050 before declining gradually, projected an increase of between 2.1 and 3.5 °C (3.8 and 6.3 °F) by 2100.

Many climate scientists agree that significant societal, economic, and ecological damage would result if the global average temperature rose by more than 2 °C (3.6 °F) in such a short time. Such damage would include increased extinction of many plant and animal species, shifts in patterns of agriculture , and rising sea levels. By 2015 all but a few national governments had begun the process of instituting carbon reduction plans as part of the Paris Agreement , a treaty designed to help countries keep global warming to 1.5 °C (2.7 °F) above preindustrial levels in order to avoid the worst of the predicted effects. Whereas authors of the 2018 special report noted that should carbon emissions continue at their present rate, the increase in average near-surface air temperature would reach 1.5 °C sometime between 2030 and 2052, authors of the AR6 report suggested that this threshold would be reached by 2041 at the latest.

The AR6 report also noted that the global average sea level had risen by some 20 cm (7.9 inches) between 1901 and 2018 and that sea level rose faster in the second half of the 20th century than in the first half. It also predicted, again depending on a wide range of scenarios, that the global average sea level would rise by different amounts by 2100 relative to the 1995–2014 average. Under the report’s lowest-emission scenario, sea level would rise by 28–55 cm (11–21.7 inches), whereas, under the intermediate emissions scenario, sea level would rise by 44–76 cm (17.3–29.9 inches). The highest-emissions scenario suggested that sea level would rise by 63–101 cm (24.8–39.8 inches) by 2100.

The scenarios referred to above depend mainly on future concentrations of certain trace gases, called greenhouse gases , that have been injected into the lower atmosphere in increasing amounts through the burning of fossil fuels for industry, transportation , and residential uses. Modern global warming is the result of an increase in magnitude of the so-called greenhouse effect , a warming of Earth’s surface and lower atmosphere caused by the presence of water vapour , carbon dioxide , methane , nitrous oxides , and other greenhouse gases. In 2014 the IPCC first reported that concentrations of carbon dioxide, methane, and nitrous oxides in the atmosphere surpassed those found in ice cores dating back 800,000 years.

Of all these gases, carbon dioxide is the most important, both for its role in the greenhouse effect and for its role in the human economy. It has been estimated that, at the beginning of the industrial age in the mid-18th century, carbon dioxide concentrations in the atmosphere were roughly 280 parts per million (ppm). By the end of 2022 they had risen to 419 ppm, and, if fossil fuels continue to be burned at current rates, they are projected to reach 550 ppm by the mid-21st century—essentially, a doubling of carbon dioxide concentrations in 300 years.

A vigorous debate is in progress over the extent and seriousness of rising surface temperatures, the effects of past and future warming on human life, and the need for action to reduce future warming and deal with its consequences. This article provides an overview of the scientific background related to the subject of global warming. It considers the causes of rising near-surface air temperatures, the influencing factors, the process of climate research and forecasting, and the possible ecological and social impacts of rising temperatures. For an overview of the public policy developments related to global warming occurring since the mid-20th century, see global warming policy . For a detailed description of Earth’s climate, its processes, and the responses of living things to its changing nature, see climate . For additional background on how Earth’s climate has changed throughout geologic time , see climatic variation and change . For a full description of Earth’s gaseous envelope, within which climate change and global warming occur, see atmosphere .

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Causes and Effects of Climate Change

Fossil fuels – coal, oil and gas – are by far the largest contributor to global climate change, accounting for over 75 per cent of global greenhouse gas emissions and nearly 90 per cent of all carbon dioxide emissions. As greenhouse gas emissions blanket the Earth, they trap the sun’s heat. This leads to global warming and climate change. The world is now warming faster than at any point in recorded history. Warmer temperatures over time are changing weather patterns and disrupting the usual balance of nature. This poses many risks to human beings and all other forms of life on Earth. 

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On Chile’s Huapi Island, native forests have become fragmented, making the soils poorer and drier and leaving the population vulnerable to the effects of climate change. Now, thanks to the restoration efforts of Indigenous Peoples, native trees are making a comeback.

Early warning systems are saving lives in Central Asia

As Central Asia grapples with the increasing frequency and severity of climate-induced hazards, the importance of robust early warning systems cannot be overstated. However, countries need both technical knowledge and resources to effectively implement these systems on a large scale. Japan has been a reliable ally for countries, helping advance early warning systems and increase resilience in the region.

Facts and figures

• What is climate change?
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Cutting emissions

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What Is Climate Change?

In this educational video, learn why the climate is changing, how it affects us, and what we can do about it.

Climate Change Causes and Effects

Climate change is rapidly altering our world in profound ways. Human activity has already increased the earth’s temperature by about 2°F since 1880. As the planet continues to get hotter, through a process known as global warming, the dangers intensify. Millions of people could be displaced and vital infrastructure could be destroyed. Climate change’s effects are far-reaching and varied and touch virtually every aspect of life on the earth: extreme heat events, rising sea levels, deeper droughts, desertification, bigger wildfires, and more intense storms.

Because climate change poses such an extraordinary threat to the planet, it needs to be addressed. There are no clear-cut answers to this global challenge, but it is not insurmountable. Countries are already taking steps to adapt to climate change and mitigate its effects. Blueprints exist, but they need to be used more widely and more effectively, because the longer action is delayed, the worse climate change becomes—and the more difficult it will be to endure.

Earth's Changing Climate

Climate change is a long-term shift in global or regional climate patterns. Often climate change refers specifically to the rise in global temperatures from the mid 20th century to present.

Earth Science, Geography, Human Geography, Physical Geography

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Climate  is the long-term pattern of weather in a particular area. Weather can change from hour to hour, day to day, month to month or even from year to year. For periods of 30 years or more, however, distinct  weather patterns occur. A  desert  might experience a rainy week, but over the long term, the region receives very little rainfall . It has a dry climate .

Because climates are mostly constant, living things can  adapt  to them. Polar bears have adapted to stay warm in  polar climates , while cacti have evolved to hold onto water in  dry climates . The  enormous  variety of life on Earth results in large part from the variety of climates that exist.

Climates do change, however—they just change very slowly, over hundreds or even thousands of years. As climates change, organisms that live in the area must adapt ,  relocate , or risk going  extinct .

Earth’s Changing Climate Earth’s climate has changed many times. For example,  fossils from the Cretaceous period (144 to 65 million years ago) show that Earth was much warmer than it is today.  Fossilized plants and animals that normally live in warm  environments have been found at much higher  latitudes than they could survive at today. For instance,  breadfruit  trees ( Artocarpus altilis ), now found on  tropical   islands , grew as far north as Greenland.

Earth has also experienced several major  ice ages —at least four in the past 500,000 years. During these periods, Earth’s  temperature   decreased , causing an  expansion  of  ice sheets and  glaciers . The most recent Ice Age began about two million years ago and peaked about 20,000 years ago. The ice caps began retreating 18,000 years ago. They have not disappeared completely, however. Their presence in Antarctica and Greenland suggests Earth is still in a sort of ice age. Many scientists believe we are in an  interglacial period , when warmer temperatures have caused the ice caps to  recede . Many centuries from now, the glaciers may advance again. Climatologists look for evidence of past climate change in many different places. Like clumsy criminals, glaciers leave many clues behind them. They scratch and  scour   rocks as they move. They deposit sediment  known as glacial till. This sediment sometimes forms mounds or ridges called  moraines . Glaciers also form elongated oval hills known as  drumlins . All of these geographic features on land that currently has no glaciers suggest that glaciers were once there. Scientists also have chemical evidence of ice ages from sediments and  sedimentary rocks . Some rocks only form from glacial material. Their presence under the ocean or on land also tells scientists that glaciers were once present in these areas. Scientists also have paleontological evidence—fossils. Fossils show what kinds of animals and plants lived in certain areas. During ice ages, organisms that are adapted to cold weather can increase their range , moving closer to the  Equator . Organisms that are adapted to warm weather may lose part of their  habitat , or even go extinct.

Climate changes occur over shorter periods, as well. For example, the so-called  Little Ice Age  lasted only a few hundred years, peaking during the 16th and 17th centuries. During this time, average global temperatures were 1 to 1.5 degrees Celsius (2 to 3 degrees Fahrenheit) cooler than they are today.

A change of one or two degrees might not seem like a lot, but it was enough to cause some pretty massive effects. For instance, glaciers grew larger and sometimes engulfed whole mountain villages. Winters were longer than usual, limiting the growing seasons of  crops . In northern Europe, people deserted farms and villages to avoid  starvation .

One way scientists have learned about the Little Ice Age is by studying the rings of trees that are more than 300 years old. The thickness of  tree rings is related to the amount of the trees’ annual growth. This in turn is related to climate changes. During times of  drought  or cold, trees could not grow as much. The rings would be closer together.

Some climate changes are almost predictable . One example of regular climate change results from the warming of the surface waters of the tropical eastern Pacific Ocean. This warming is called El Niño —The Child—because it tends to begin around Christmas. In normal years,  trade winds blow steadily across the ocean from east to west, dragging warm surface water along in the same direction. This produces a shallow layer of warm water in the eastern Pacific and a buildup of warm water in the west. Every few years, normal winds falter and ocean currents reverse. This is El Niño. Warm water deepens in the eastern Pacific. This, in turn, produces  dramatic  climate changes. Rain decreases in Australia and southern Asia, and freak storms may pound Pacific islands and the west coast of the Americas. Within a year or two, El Niño ends, and climate systems return to normal.

Natural Causes of Climate Change Climate changes happen for a variety of reasons. Some of these reasons have to do with Earth’s  atmosphere . The climate change brought by El Niño, which relies on winds and ocean currents, is an example of natural atmospheric changes. Natural climate change can also be affected by forces outside Earth’s atmosphere. For instance, the 100,000-year cycles of ice ages are probably related to changes in the tilt of Earth’s  axis  and the shape of its  orbit  around the sun. Those planetary factors change slowly over time and affect how much of the sun’s energy reaches different parts of the world in different seasons.

The impact of large  meteorites on Earth could also cause climate change . The impact of a meteor would send millions of tons of  debris  into the atmosphere . This debris would block at least some of the sun’s rays, making it cold and dark. This climate change would severely limit what organisms could survive. Many  paleontologists believe the impact of a meteor or comet contributed to the extinction of the dinosaurs .  Dinosaurs simply could not survive in a cool, dark climate . Their bodies could not adjust to the cold, and the dark limited the growth of plants on which they fed.

Plate tectonics  also play a role in climate changes. Earth’s continental plates have moved a great deal over time. More than 200 million years ago, the continents were  merged together as one giant landmass called  Pangaea . As the continents broke apart and moved, their positions on Earth changed, and so did the movements of ocean currents. Both of these changes had effects on climate. Changes in  greenhouse gases in the atmosphere also have an impact on climate change. Gases like  carbon dioxide  trap the sun’s heat in Earth’s atmosphere, causing temperatures on the surface to rise.  Volcanoes —both on land and under the ocean—release greenhouse gases, so if the eruption only reaches the troposphere the additional gases contribute to warming. However, if the eruption is powerful enough to reach the stratosphere particles reflect sunlight back into space causing periods of cooling regionally.

Human Causes of Climate Change Some human activities release greenhouse gases—burning  fossil fuels for  transportation  and  electricity , or using  technology  that increases meat production, for instance. Trees absorb carbon dioxide, so cutting down forests for  timber  or  development  contributes to the greenhouse effect . So do factories that  emit   pollutants into the atmosphere.

Many scientists are worried that these activities are causing dramatic and dangerous changes in Earth’s climate. Average temperatures around the world have risen since about 1880, when scientists began tracking them. The seven warmest years of the 20th century occurred in the 1990s. This warming trend may be a sign that the greenhouse effect is increasing because of human activity. This climate change is often referred to as “ global warming .” Global warming is often linked to the burning of fossil fuels— coal ,  oil , and  natural gas —by industries and cars. Warming is also linked to the destruction of tropical forests. The University of California Riverside and NASA estimate human activity has increased the amount of carbon dioxide in the atmosphere by about 30 percent in the past 150 years. The amount of methane , a potent greehouse gas produced by decomposing plant and animal matter, is also increasing. Increased amounts of methane in Earth’s atmosphere are usually linked to  agricultural development  and industrial technology. As economies grow, populations consume more goods and throw away more materials. Large landfills , filled with decomposing waste, release tons of methane into the atmosphere. Chlorofluorocarbon (CFC) ,  hydrochlorofluorocarbon  (HCFC), and  hydrofluorocarbon  (HFC) chemicals are used in refrigeration and aerosol sprays. These chemicals are also greenhouse gases. Many countries are working to  phase out  their use, and some have laws to prevent companies from manufacturing them.

Global Warming

As the proportion of greenhouse gases in the atmosphere rises, so does the temperature of Earth. Climatologists worry that the global temperature will increase so much that ice caps will begin melting within the next several decades . This would cause the  sea level  to rise. Coastal areas, including many low-lying islands, would be flooded. Severe climate change may bring more severe weather patterns—more  hurricanes ,  typhoons , and  tornadoes . More precipitation would fall in some places and far less in others. Regions where crops now grow could become deserts. As climates change, so do the habitats for living things. Animals that live in an area may become threatened. Many human societies depend on specific crops for food , clothing, and trade . If the climate of an area changes, the people who live there may no longer be able to grow the crops they depend on for survival. Some scientists worry that as Earth warms,  tropical diseases such as  malaria ,  West Nile virus , and  yellow fever  will expand into more  temperate  regions. The temperature will continue to rise unless preventive steps are taken. Most climatologists agree that we must reduce the amount of greenhouse gases released into the atmosphere. There are many ways to do this, including:

• Drive less. Use  public transportation ,  carpool , walk, or ride a bike.
• Fly less. Airplanes produce huge amounts of greenhouse gas emissions .
• Reduce, reuse, and recycle.
• Plant a tree. Trees absorb carbon dioxide, keeping it out of the atmosphere.
• Use less electricity.
• Eat less meat. Cows are one of the biggest methane producers.
• Support alternative energy sources that don’t burn fossil fuels, such as  solar power  and  wind energy .

The climate has changed many times during Earth’s history, but the changes have occurred slowly, over thousands of years. Only since the Industrial Revolution have human activities begun to influence climate—and scientists are still working to understand what the  consequences might be.

Cool Warming Could the current phase of climate change cause another Little Ice Age? As strange as it sounds, some scientists believe it could. If melting glaciers release large amounts of freshwater into the oceans, this could disrupt the ocean conveyor belt, an important circulation system that moves seawater around the globe. Stopping this cycle could possibly cause cooling of 3 to 5 degrees Celsius (5-9 degrees Fahrenheit) in the ocean and atmosphere.

Early Squirrels The North American red squirrel has started breeding earlier in the year as a result of climate change. Food becomes available to the squirrels earlier because of warmer winters.

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April 3, 2024

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You Asked, We Answered: Some Burning Climate Questions

Reporters from the Climate Desk gathered reader questions and are here to help explain some frequent puzzlers.

What’s one thing you want to know about climate change? We asked, and hundreds of you responded.

The topic, like the planet, is vast. Overwhelming. Complex. But there’s no more important time to understand what is happening and what can be done about it.

Why are extreme cold weather events happening if the planet is warming?

I understand that scientists believe that some extreme cold weather events are due to climate change, but I don’t quite understand how, especially if Earth is getting warmer overall. Could you explain this? — Gabriel Gutierrez, West Lafayette, Ind.

By Maggie Astor

The connection between climate change and extreme cold weather involves the polar jet stream in the Northern Hemisphere, strong winds that blow around the globe from west to east at an altitude of 5 to 9 miles. The jet stream naturally shifts north and south, and when it shifts south, it brings frigid Arctic air with it.

A separate wind system, called the polar vortex , forms a ring around the North Pole. When the vortex is temporarily disrupted — sometimes stretched or elongated, and other times broken into pieces — the jet stream tends to take one of those southward shifts. And research “suggests these disruptions to the vortex are happening more often in connection with a rapidly warming, melting Arctic, which we know is a clear symptom of climate change,” said Jennifer A. Francis, a senior scientist at the Woodwell Climate Research Center.

In other words, as climate change makes the Arctic warmer, the polar vortex is being more frequently disrupted in ways that allow Arctic air to escape south. And while temperatures are increasing on average, Arctic air is still frigid much of the time. Certainly frigid enough to cause extreme cold snaps in places like, say, Texas that are not accustomed to or prepared for them.

Where the extreme cold occurs depends on the nature of the disruption to the polar vortex. One type of disruption brings Arctic air into Europe and Asia. Another type brings Arctic air into the United States, and “that’s the type of polar vortex disruption that’s increasing the fastest,” said Judah L. Cohen, the director of seasonal forecasting at Atmospheric and Environmental Research, a private organization that works with government agencies.

It is important to note that these atmospheric patterns are extremely complicated, and while studies have shown a clear correlation between the climate-change-fueled warming of the Arctic and these extreme cold events, there is some disagreement among scientists about whether the warming of the Arctic is directly causing the extreme cold events. Research on that question is ongoing.

How will climate change affect biodiversity?

What impact will climate change have on biodiversity? How are they interlinked? How do the roles of developing versus developed countries differ, for example the United States and India? — A reader in India

By Catrin Einhorn

Warmer oceans are killing corals . Rising sea levels threaten the beaches that sea turtles need for nesting, and hotter temperatures are causing more females to be born. Changing seasons are increasingly out of step with the conditions species have evolved to depend on.

And then there are the polar bears , long a symbol of what could be lost in a warming world.

Climate change is already affecting plants and animals in ways that scientists are racing to understand. One study predicted sudden die offs , with large segments of ecosystems collapsing in waves. This has already started in coral reefs, scientists say, and could start in tropical forests by the 2040s.

Keeping global warming under 2 degrees Celsius, or 3.6 degrees Fahrenheit, the upper limit outlined by the Paris Agreement, would reduce the number of species exposed to dangerous climate change by 60 percent, the study found.

Despite these grim predictions, climate change isn’t yet the biggest driver of biodiversity loss. On land, the largest factor is the ways in which people have reshaped the terrain itself, creating farms and ranches, towns and cities, roads and mines from what was once habitat for myriad species. At sea, the main cause of biodiversity loss is overfishing. Also at play: pollution, introduced species that outcompete native ones, and hunting. A sobering report in 2019 by the leading international authority on biodiversity found that around a million species were at risk of extinction, many within decades.

While climate change will increasingly drive species loss, that’s not the only way in which the two are interlinked. Last year the same biodiversity panel joined with its climate change counterpart to issue a paper declaring that neither crisis could be addressed effectively on its own. For example, intact ecosystems like peatlands and forests both nurture biodiversity and sequester carbon; destroy them, and they turn into emitters of greenhouse gasses as well as lost habitat.

What to do? The science is clear that the world must transition away from fossil fuels far more quickly than is happening. Deforestation must stop . Consuming less meat and dairy would free up farmland for restoration , providing habitat for species and stashing away carbon. Ultimately, many experts say, we need a transformation from an extraction-based economy to a circular one. Like nature’s cycle, our waste — old clothes, old smartphones, old furniture — must be designed to provide the building blocks of what comes next.

Countries around the world are working on a new United Nations biodiversity agreement , which is expected to be approved later this year. One sticking point: How much money wealthy countries are willing to give poorer ones to protect intact natural areas, since wealthy countries have already largely exploited theirs.

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What’s the status of U.S. climate legislation and emissions?

Where is the trimmed back version of climate legislation at? Joe Manchin reportedly said he would support such a bill. What do you know about the bill and will it pass with just Democrats? — Richard Buttny, Virgil, N.Y.

What is the current stated U.S. goal regarding reducing greenhouse gases and climate change, and how likely is it that we will achieve that goal? What do we need to do today to make progress toward achieving that goal? — Kathy Gray, Oak Ridge, Tenn.

By Lisa Friedman

Richard, as to the last part of your question, honestly, at this point your guess is as good as ours.

But here is what we know so far. Senator Joe Manchin III, Democrat of West Virginia, the most powerful man in Congress because his support in an evenly divided Senate is key, effectively killed President Biden’s Build Back Better climate and social spending legislation when he ended months of negotiations last year, saying he could not support the package .

A few weeks ago amid talks of revived discussions, Mr. Manchin was blunt. “There is no Build Back Better legislation,” he told reporters. Mr. Manchin also has not committed to passing a smaller version of the original $1 trillion spending plan. He has, however, voiced support for an “all of the above” energy package that increases oil and gas development.

Democrats hope that billions of dollars in tax incentives for wind, solar, geothermal and electric vehicle charging stations can also make its way into such a package. But relations between the White House and Mr. Manchin are rocky and it is unclear whether such a bill could pass before lawmakers leave town for an August recess.

To your emissions question, Kathy, Mr. Biden has pledged to cut United States emissions 50 to 52 percent below 2005 levels by 2030 . Energy experts say it is a challenging but realistic goal, and critical for helping the world avert the worst impacts of climate change.

It’s not going to be easy. So far there are few regulations and even fewer laws that can help achieve that target. Mr. Biden’s centerpiece legislation, the Build Back Better Act, includes $550 billion in clean energy tax incentives that researchers said could get the country about halfway to its goal. But, as noted, that bill is stalled in the Senate . Even if it manages to win approval this year, the administration will still have to enact regulations on things like power plants and automobile emissions to meet the target.

Will our drinking water be safe?

A lot of coverage on climate change deals with rising sea levels and extreme weather — droughts, floods, etc. My question is more about how climate change will affect drinking water and access to safe clean water. Are we in danger within our current lifetime to see an impact to safe water within the U.S. due to climate change? — Jessica, Silver Spring, Md.

By Christopher Flavelle

Climate change threatens Americans’ access to clean drinking water in a number of ways. The most obvious is drought: Rising temperatures are reducing the snowpack that supplies drinking water for much of the West.

But drought is far from the only climate-related threat to America’s water. Along the coast, cities like Miami that draw drinking water from underground aquifers have to worry about rising seas pushing saltwater into those aquifers , a process called saltwater intrusion. And rising seas also push up groundwater levels, which can cause septic systems to stop working, pushing unfiltered human waste into that groundwater.

Even in cities far from the coast, worsening floods are overwhelming aging sewer systems , causing untreated storm water and sewage to reach rivers and streams more frequently . And some 2,500 chemical sites are in areas at risk of flooding, which could cause those chemicals to leach into the groundwater.

In some cases, protecting drinking water from the effects of climate change is possible, so long as governments can find enough money to upgrade infrastructure — building new systems to contain storm water, for example, or better protect chemicals from being released during a flood.

Far harder will be finding new supplies of water to make up for what’s lost as temperatures rise. Some communities are responding by pumping more water from the ground. But if those aquifers are depleted faster than rainwater can replenish them, they will eventually run dry, a concern with the Ogallala Aquifer that supports much of the High Plains.

Even with significant reductions in water use, climate change could reduce the number of people that some regions can support, and leave more areas dependent on importing water.

Can you solve drought by piping water across the country?

Why don’t we create a national acequia system to capture excess rain falling primarily in the Eastern United States and pipeline it to the drought in the West? — Carol P. Chamberland, Albuquerque, N.M

The idea of taking water from one community and giving it to another has some basis in American history. In 1913, Los Angeles opened an aqueduct to carry water from Owens Valley, 230 miles north of the city, to sustain its growth.

But the project, in addition to costing some $23 million at the time, greatly upset Owens Valley residents, who so resented losing their water that they took to dynamiting the aqueduct. Repeatedly .

Today, there are some enormous water projects in the United States, though building a pipeline that spanned a significant stretch of the country would be astronomically more difficult. The distance between Albuquerque, for example, and the Mississippi River — perhaps the closest hypothetical starting point for such a pipeline — is about 1,000 miles, crossing at least three states along the way. Moving that water all the way to Los Angeles would mean piping it at least 1,800 miles across five states.

So the engineering and permitting challenges alone would be daunting. And that’s assuming the local and state governments that would have to give up their water would be willing to do so.

China dealt with similar challenges to build a colossal network of waterways that is transferring water from the country’s humid south to its dry north. But of course, China’s system of government makes engineering feats of that scale somewhat more feasible to pull off.

For the United States, it would be easier to just build a series of desalination plants along the West coast, according to Greg Pierce, director of the Human Right to Water Solutions Lab at the University of California, Los Angeles. And before turning to desalination, which is itself energy-intensive and thus expensive, communities in the West should work harder at other steps, such as water conservation and recycling, he said.

“It’s not worth it,” Dr. Pierce said of the pipeline idea. “You’d have to exhaust eight other options first.”

Is the weather becoming more extreme than scientists predicted?

How can we have faith in climate modeling when extreme events are much worse than predicted? Given “unexpected” extreme events like the 2021 Pacific Northwest heat wave and extreme heat in Antarctica that appear to shock scientists, it’s difficult for me to trust the I.P.C.C.’s framing that we haven’t run out of time. — Kevin, Herndon, Va.

By Raymond Zhong

Climate scientists have said for a long time that global warming is causing the intensity and frequency of many types of extreme weather to increase. And that’s exactly what has been happening. But global climate models aren’t really designed to simulate extreme events in individual regions. The factors that shape individual heat waves, for instance, are very local. Large-scale computer models simply can’t handle that level of detail quite yet.

That said, sometimes there are events that seem so anomalous that they make scientists wonder if they reflect something totally new and unforeseen, a gap in our understanding of the climate. Some researchers put the 2021 Pacific Northwest heat wave in that category, and are working to figure out whether they need to re-evaluate some of their assumptions.

For its part, the I.P.C.C. has hardly failed to acknowledge what’s happening with extreme weather. But its mandate is to assess the whole range of climate research, which might make it lean toward the middle of the road in its summaries. A decade ago, when a group of researchers looked back at the panel’s assessments from the early 2000s, they found that it generally underestimated the actual changes in sea level rise, increases in surface temperatures, intensity of rainfall and more. They blamed the instinct of scientists to avoid making conclusions that seem “excessively dramatic,” perhaps out of fear of being called alarmist.

The panel’s latest report, from April , concluded that we haven’t run out of time to slow global warming, but only if nations and societies make some huge changes right away. That’s a big if.

How can I hear from climate scientists themselves?

Why are climate change scientists faceless, aloof, terrible communicators and absent from social media? — A reader in Dallas

Climate science may not yet have its Bill Nye or its Neil deGrasse Tyson, but plenty of climate scientists are passionate about communicating their work to the public. Lots of them are on Twitter. Here’s a (very small) cross-section of people to follow, in alphabetical order:

Alaa Al Khourdajie : Senior scientist in London with the Intergovernmental Panel on Climate Change, the body of experts convened by the United Nations that puts out regular, authoritative surveys of climate research. Tweets on climate change economics and climate diplomacy.

Andrew Dessler : Professor of atmospheric sciences at Texas A&M University. Elucidator of energy and renewables, climate models and Texas.

Zeke Hausfather : Climate research lead at the payment processing company Stripe and scientist at Berkeley Earth, a nonprofit research group. A seemingly tireless chronicler, charter and commentator on all things climate.

David Ho : Climate scientist at the University of Hawaii at Manoa and École Normale Supérieure in Paris. Talks oceans and carbon dioxide removal, with wry observations on transit, cycling and life in France, too.

Twila Moon : Deputy lead scientist at the National Snow and Ice Data Center in Boulder, Colo. Covers glaciers, polar regions and giant ice sheets, and why we should all care about what happens to them.

Maisa Rojas : Climatologist at the University of Chile and Chile’s current environment minister. Follow along for slices of life at the intersection of science and government policy.

Sonia I. Seneviratne : Professor of land-climate dynamics at ETH Zurich in Switzerland. Tweets on extreme weather, greenhouse gas emissions and European energy policy.

Chandni Singh : Researcher on climate adaptation at the Indian Institute for Human Settlements in Bangalore. Posts about how countries and communities are coping with climate change, in both helpful ways and not so helpful ones.

Kim Wood : Geoscientist and meteorologist at Mississippi State University. A fount of neat weather maps and snarky GIFs.

What kind of trees are best to plant for the planet?

The world is trying to reforest the planet by planting nonnative trees like eucalyptus. Is this another disastrous plan? Shouldn’t they be planting native trees? — Katy Green, Nashville

Ecologists would say planting native trees is the best choice. We recently published an article on this very topic , examining how tree planting can resurrect or devastate ecosystems, depending on what species are planted and where.

To be sure, people need wood and other tree products for all kinds of reasons, and sometimes nonnative species make sense. But even when the professed goal is to help nature, the commercial benefits of certain trees, like Australian eucalyptus in Africa and South America or North American Sitka spruce in Europe, often win out.

A new standard is in development that would score tree planting projects on how well they’re doing with regard to biodiversity, with the aim of helping those with poor scores to improve.

The same ecological benefit of planting native species also holds true for people’s yards. Doug Tallamy, a professor of entomology at the University of Delaware, worked with the National Wildlife Federation to develop this tool to help people find native trees, shrubs and flowers that support the most caterpillars, which in turn feed baby birds .

Can we engineer solutions to atmospheric warming?

Why are we not investing in scalable solutions that can remove carbon or reduce solar radiation? — Hayes Morehouse, Hayward, Calif.

By Henry Fountain

As a group, these types of solutions are referred to as geoengineering, or intentional manipulation of the climate. Geoengineering generally falls into two categories: removing some of the carbon dioxide already in the atmosphere so Earth traps less heat, known as direct air capture, or reducing how much sunlight reaches Earth’s surface so that there is less heat to begin with, usually called solar radiation management.

There are a few companies developing direct air capture machines, and some have deployed them on a small scale. According to the International Energy Agency, these projects capture a total of about 10 thousand tons of CO2 a year, a tiny fraction of the roughly 35 billion tons of annual energy-related emissions. Removing enough CO2 to have a climate impact would take a long time and require many thousands of machines, all of which would need energy to operate.

The captured gas would also have to be securely stored to keep it from re-entering the atmosphere. Those hurdles make direct air capture a long shot, especially since, for now at least, there are few financial incentives to overcome them. No one wants to pay to remove carbon dioxide from the air and bury it underground.

Solar radiation management is a different story. The basics of how to do it are known: inject some kind of chemical (perhaps sulfur dioxide) into the upper atmosphere, where it would reflect more of the sun’s rays. Relatively speaking, it wouldn’t be all that expensive (a fleet of high-flying planes would probably suffice) although once started it would have to continue indefinitely.

The major hurdle to developing the technology has been grave concern among many scientists, policymakers and others about unintended consequences that might result, and about the lack of a structure to govern its deployment. To date, there have been almost no real-world studies of the technology .

How do we know how warm the planet was in the 1800s?

One key finding of climate science is that global temperatures have increased by 2 degrees Fahrenheit since the late 1800s. How can we possibly have reliable measures of global temperatures from back then, keeping in mind that oceans cover about 70 percent of the globe and that a large majority of land has never been populated by humans to any significant degree? — Robert, Madison, Wis.

The mercury thermometer was invented in the early 1700s, and by the mid- to late 19th century, local temperatures were being monitored continuously in many locations, predominantly in the United States, Europe and the British colonies. By 1900, there were hundreds of recording stations worldwide, but over half of the Southern Hemisphere still wasn’t covered. And the techniques could be primitive. To measure temperatures at the sea’s surface, for instance, the most common method before about 1940 was to toss a bucket overboard a ship, haul it back up with a rope and read the temperature of the water inside.

To turn these spotty local measurements into estimates of average temperatures globally, across both land and ocean, climate scientists have had to perform some highly delicate analysis . They’ve used statistical models to fill in the gaps in direct readings. They’ve taken into account when weather stations changed locations or were situated close to cities that were hot for reasons unrelated to larger temperature trends.

They have also used some clever techniques to try to correct for antiquated equipment and methods. Those bucket readings , for example, might be inaccurate because the water in the bucket cooled down as it was pulled aboard. So scientists have scoured various nations’ maritime archives to determine what materials their sailors’ buckets were made of — tin, wood, canvas, rubber — during different periods in history and adjusted the way they incorporate those temperature recordings into their computations.

Such analysis is fiendishly tricky. The numbers that emerge are uncertain estimates, not gospel truth. Scientists are working constantly to refine them. Today’s global temperature measurements are based on a much broader and more quality-controlled set of readings, including from ships and buoys in the oceans.

But having a historical baseline, even an imperfect one, is important. As Roy L. Jenne, a researcher at the National Center for Atmospheric Research, wrote in a 1975 report on the institution’s collections of climate data: “Although they are not perfect, if they are used wisely they can help us find answers to a number of problems.”

Does producing batteries for electric cars damage the environment more than gas vehicles do?

Is the environmental damage collecting metals/producing batteries for electric cars more dangerous to the environment than gas powered vehicles? — Sandy Rogers, San Antonio, Texas

By Hiroko Tabuchi

There’s no question that mining the metals and minerals used in electric car batteries comes with sizable costs that are not just environmental but also human.

Much of the world’s cobalt, for example, is mined in the Democratic Republic of Congo , where corruption and worker exploitation has been widespread. Extracting the metals from their ores also requires a process called smelting, which can emit sulfur oxide and other harmful air pollution.

Beyond the minerals required for batteries, electric grids still need to become much cleaner before electric vehicles are emissions free.

Most electric vehicles sold today already produce significantly fewer planet-warming emissions than most cars fueled with gasoline, but a lot still depends on how much coal is being burned to generate the electricity they use.

Still, consider that batteries and other clean technology require relatively tiny amounts of these critical minerals, and that’s only to manufacture them. Once a battery is in use, there are no further minerals necessary to sustain it. That’s a very different picture from oil and gas, which must constantly be drilled from the ground, transported via pipelines and tankers, refined and combusted in our gasoline cars to keep those cars moving, said Jim Krane, a researcher at Rice University’s Baker Institute for Public Policy in Houston. In terms of environmental and other impacts, he said, “There’s just no comparison.”

How close are alternatives to fuel-powered aircraft?

As E. V.s are to gas-powered cars, are there greener alternatives to fuel-powered planes that are close to commercialization? — Rashmi Sarnaik, Boston

There are alternatives to fossil-fuel-powered aircraft in development, but whether they are close to commercialization depends on how you define “close.” It’s probably fair to say that the day when a significant amount of air travel is on low- or zero-emissions planes is still far-off.

There has been some work on using hydrogen , including burning it in modified jet engines. Airbus and the engine manufacturer CFM International expect to begin flight testing a hydrogen-fueled engine by the middle of the decade.

As with cars, though, most of the focus in aviation has been on electric power and batteries. The main problem with batteries is how little energy they supply relative to their weight. In cars that’s less of an obstacle (they don’t have to get off the ground, after all) but in aviation, batteries severely limit the size of the plane and how far it can fly.

One of the biggest battery-powered planes to fly so far was a modified Cessna Grand Caravan, test-flown by two companies, Magnix and Aerotec. Turboprop Grand Caravans can carry 10 or more people up to 1,200 miles. The companies said theirs could fly four or five people 100 miles or less.

The limitations of batteries, at least for now, have led some companies to work on other designs. Some use fuel cells, which work like batteries but can continuously supply electricity using hydrogen or other fuel. Others use hybrid systems — like hybrid cars, combining batteries and fossil-fuel-powered engines. In one approach, the engines provide some power and also keep the batteries charged. In another, the engines are used in takeoff and descent, when more power is needed, and the batteries for cruising, which requires less power. That keeps the number of batteries, and the weight, down.

Can countries meet the goals they set in the Paris agreement?

What countries, if any, have a realistic chance of meeting their Paris agreement pledges? — Michael Svetly, Philadelphia

According to Climate Action Tracker , a research group that analyzes climate goals and policies, very few. Ahead of United Nations talks in Glasgow last year, the organization found most major emitters of carbon dioxide, including the United States and China, are falling short of their pledge to stabilize global warming around 1.5 degrees Celsius, or 2.7 degrees Fahrenheit.

A few are doing better than most, including Costa Rica and the United Kingdom. Just one country was on track to meet its promises: Gambia, a small West African nation that has been bolstering its renewable energy use.

What will happen to N.Y.C.?

How is N.Y.C. planning for relocation or redevelopment, or both, of its many low-lying neighborhoods as floodwaters become too high to levee? — A reader in North Bergen, N.J.

New York City has yet to announce plans to fully relocate entire neighborhoods threatened by climate change, with all the steps that would entail: determining which homes to buy, getting agreement from homeowners, finding a new patch of land for the community, building new infrastructure, securing funding and so on.

Relocation projects on that scale, often described as “managed retreat,” remain extremely rare in the United States. What projects have been attempted so far have mostly been in rural areas or small towns , and their success has been mixed.

And the idea of pulling back from the water, while never easy, is especially fraught in New York City, which has some of the highest real estate values in the country. Those high values have been used to justify fantastically expensive projects to protect low-lying land in the city, rather than abandon it — like a $10 billion berm along the South Street Seaport , or a $119 billion sea wall in New York Harbor .

Perhaps unsurprisingly, then, the city’s most recent Comprehensive Waterfront Plan , issued in December, makes no mention of managed retreat. But the plan does include what it calls “housing mobility” — policies aimed at helping individual households move to safer areas, for example by giving people money to buy a new home on higher ground, as well as paying for moving and other costs. The city also says it is limiting the density of new development in high-risk areas.

Robert Freudenberg, a vice president of the Regional Plan Association, a nonprofit planning group in New York, New Jersey and Connecticut, gave city officials credit for beginning to talk about the idea that some areas can’t be protected forever.

“It’s an extremely challenging topic,” Mr. Freudenberg said. But as flooding gets worse, he added, “we can’t not talk about it.”

As oceans rise, will the Great Lakes, too?

The oceans are predicted to rise and affect coastal areas and cities, however, does this rise also affect the coastal areas of the Great Lakes, as the lakes are connected to the Atlantic Ocean via the St. Lawrence River and one would have to assume they would eventually be impacted? — Terri Messinides, Madison, Wis.

The Great Lakes are not directly threatened by rising oceans because of their elevation: The lowest of them, Lake Ontario, is about 240 feet above sea level. The St. Lawrence River carries water from the lakes to the Atlantic Ocean, but because of the elevation change, rising waters in the Atlantic can’t travel in the other direction.

That said, climate change is causing increasingly frequent and intense storms in the Great Lakes region, and the effects, including higher water levels and more flooding, are in many respects the same as those caused by rising seas. It’s just a different manifestation of climate change.

When it comes to precipitation, the past five years, from April 2017 through March 2022, the last month for which complete data is available, have been the second-wettest on record for the Great Lakes Basin, according to records kept by the National Oceanic and Atmospheric Administration . The water has risen accordingly. In 2019, water levels in the lakes hit 100-year highs , causing severe flooding and shoreline erosion.

At the same time, higher temperatures increase the rate of evaporation, which can lead to abnormally low water levels. People who live around the Great Lakes can expect to see both extremes — high water driven by severe rainfall, and low water driven by evaporation — happen more often as the climate continues to warm.

What is the environmental cost of cryptocurrency?

Can you tell us about the damage being done to our environment by crypto mining? I’ve heard the mining companies are trying to switch to renewable energy, yet at the same time reopening old coal power plants to provide the huge amounts of electricity they need. — Barry Engelman, Santa Monica, Calif.

Cryptomining, the enigmatic way in which virtual cryptocurrencies like Bitcoin are created (and which is also behind technology like NFTs ), requires a whole lot of computing power, is highly energy-intensive and generates outsize emissions. We delved into that process, and its environmental impact in this article — but suffice to say the problem isn’t going away soon.

The way Bitcoin is set up, using a process called “proof of work,” means that as interest in cryptocurrencies grows and more people start mining, more energy is required to mine a single Bitcoin. Researchers at Cambridge University estimate that mining Bitcoin uses more electricity than midsize countries like Norway. In New York, an influx of Bitcoin miners has led to the reopening of mothballed power plants.

But you might wonder about the traditional financial system: doesn’t that use energy, too? Yes, of course. But Bitcoin, for all its hype, still makes up just a few percent of all the world’s money or its transactions. So even though one industry study estimated that Bitcoin consumes about a 10th of the energy required by the traditional banking system, that still means Bitcoin’s energy use is outsize.

To address its high emissions footprint, cryptomining has increasingly tapped into renewable forms of energy, like hydroelectric power. But figuring out exactly just how much renewable energy Bitcoin miners use can be tricky. For one, we don’t exactly know where many of these miners are. We do know a lot of crypto miners used to be in China, where they had access to large amounts of hydro power. But now that they’ve largely been kicked out, cryptomining’s global climate impact has likely gotten worse .

In the United States, cryptominers have started to tap an unconventional new energy source: drilled gas, collected at oil and gas wells. The miners argue that this gas would otherwise have been flared or vented into the atmosphere, so no excess emissions are created. The reality is not that clear cut: If the presence of those cryptominers disincentivizes oil and gas companies from piping away that gas to be used elsewhere, any savings effect is blunted.

Other efforts are afoot to make cryptomining less damaging for the environment, including an alternative way of cryptomining involving a process called “proof of stake,” that doesn’t require miners to use as much energy. But unless Bitcoin, the most popular cryptocurrency, switches over, that’s going to do little to dent miners’ energy use.

How much do volcanoes contribute to global warming?

What does the data look like for greenhouse gas emissions in the last 200 years if volcanic activity was subtracted out? — Haley Rowlands, Boston

Volcanic activity generates 130 million to 440 million tons of carbon dioxide per year, according to the United States Geological Survey . Human activity generates about 35 billion tons of carbon dioxide per year — 80 times as much as the high-end estimate for volcanic activity, and 270 times as much as the low-end estimate. And that’s carbon dioxide. Human activity also emits other greenhouse gases, like methane, in far greater quantities than volcanoes.

The largest volcanic eruption in the past century was the 1991 eruption of Mount Pinatubo in the Philippines; if an explosion that size happened every day, NASA has calculated , it would still release only half as much carbon dioxide as daily human activity does. The annual emissions from cement production alone, one small component of planet-warming human activity, are greater than the annual emissions from every volcano in the world.

There is also no evidence that volcanic activity has increased over the past 200 years. While there have been more documented eruptions, researchers at the Smithsonian Institution’s Global Volcanism Program found that this was attributable not to an actual trend, but rather to “increases in populations living near volcanoes to observe eruptions and improvements in communication technologies to report those eruptions.”

All told, volcanic activity accounts for less than 1 percent of greenhouse gas emissions, which is not enough to contribute in any meaningful way to the increase we’ve seen over the past 200 years. The Intergovernmental Panel on Climate Change found in 2013 (see Page 56 of its report ) that the climatic effects of volcanic activity were “inconsequential” over the scale of a century.

Do carbon dioxide concentrations vary around the globe?

Why is the concentration of carbon dioxide in the atmosphere at Mauna Loa Observatory in Hawaii used as the global reference? It’s only one point on Earth. Do concentrations vary between different parts of the world? — Evan, Boston

At any given moment, levels of carbon dioxide in the air vary from place to place, depending on the amount of vegetation and human activity nearby. Which is why, as a location to monitor the average state of the atmosphere, at least over a large part of the Northern Hemisphere, a barren volcano in the middle of the Pacific has much to offer. It’s high above the ground and far enough from major sources of industrial pollution but still relatively accessible to researchers.

Today, the National Oceanic and Atmospheric Administration studies global carbon dioxide levels by looking at readings from Mauna Loa Observatory and a variety of other sources. These include observatories in Alaska, American Samoa and the South Pole, tall towers across the United States, and samples collected by balloons, aircraft and volunteers around the world. ( Here’s a map of all those sites.)

NOAA also checks its measurements at Mauna Loa against others from the same location, including ones taken independently, using different methods, by the Scripps Institution of Oceanography . On average, the difference in their monthly estimates is tiny.

Could a ‘new ice age’ offset global warming?

Will increases in global temperature associated with climate change be mitigated by the coming of a new “ice age?” — Suzanne Smythe, Essex, Conn.

In a “mini ice age,” if it occurred, average worldwide temperatures would drop, thus offsetting the warming that has been caused by emissions of greenhouse gases from the burning of fossil fuels in the last century and a half.

It’s a nice thought: a natural phenomenon comes to our rescue. But it’s not happening, nor is it expected to.

The idea is linked to the natural variability in the amount of the sun’s energy that reaches Earth. The sun goes through regular cycles, lasting about 11 years, when activity swings from a minimum to a maximum. But there are also longer periods of reduced activity, called grand solar minimums. The last one began in the mid-17th century and lasted seven decades.

There is some debate among scientists whether we are entering a new grand minimum . But even if we are, and even if it lasted for a century, the reduction in the sun’s output would not have a significant effect on temperatures. NASA scientists, among others, have calculated that any cooling effect would be overwhelmed by the warming effect of all the greenhouse gases we have pumped, and continue to pump, into the atmosphere.

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Our Future Is Now - A Climate Change Essay by Francesca Minicozzi, '21

Francesca Minicozzi (class of 2021) is a Writing/Biology major who plans to study medicine after graduation. She wrote this essay on climate change for WR 355/Travel Writing, which she took while studying abroad in Newcastle in spring 2020. Although the coronavirus pandemic curtailed Francesca’s time abroad, her months in Newcastle prompted her to learn more about climate change. Terre Ryan Associate Professor, Writing Department

Our Future Is Now

By Francesca Minicozzi, '21 Writing and Biology Major

 “If you don’t mind me asking, how is the United States preparing for climate change?” my flat mate, Zac, asked me back in March, when we were both still in Newcastle. He and I were accustomed to asking each other about the differences between our home countries; he came from Cambridge, while I originated in Long Island, New York. This was one of our numerous conversations about issues that impact our generation, which we usually discussed while cooking dinner in our communal kitchen. In the moment of our conversation, I did not have as strong an answer for him as I would have liked. Instead, I informed him of the few changes I had witnessed within my home state of New York.

Zac’s response was consistent with his normal, diplomatic self. “I have been following the BBC news in terms of the climate crisis for the past few years. The U.K. has been working hard to transition to renewable energy sources. Similar to the United States, here in the United Kingdom we have converted over to solar panels too. My home does not have solar panels, but a lot of our neighbors have switched to solar energy in the past few years.”

“Our two countries are similar, yet so different,” I thought. Our conversation continued as we prepared our meals, with topics ranging from climate change to the upcoming presidential election to Britain’s exit from the European Union. However, I could not shake the fact that I knew so little about a topic so crucial to my generation.

After I abruptly returned home from the United Kingdom because of the global pandemic, my conversation with my flat mate lingered in my mind. Before the coronavirus surpassed climate change headlines, I had seen the number of internet postings regarding protests to protect the planet dramatically increase. Yet the idea of our planet becoming barren and unlivable in a not-so-distant future had previously upset me to the point where a part of me refused to deal with it. After I returned from studying abroad, I decided to educate myself on the climate crisis.

My quest for climate change knowledge required a thorough understanding of the difference between “climate change” and “global warming.” Climate change is defined as “a pattern of change affecting global or regional climate,” based on “average temperature and rainfall measurements” as well as the frequency of extreme weather events. 1   These varied temperature and weather events link back to both natural incidents and human activity. 2   Likewise, the term global warming was coined “to describe climate change caused by humans.” 3   Not only that, but global warming is most recently attributed to an increase in “global average temperature,” mainly due to greenhouse gas emissions produced by humans. 4

I next questioned why the term “climate change” seemed to take over the term “global warming” in the United States. According to Frank Luntz, a leading Republican consultant, the term “global warming” functions as a rather intimidating phrase. During George W. Bush’s first presidential term, Luntz argued in favor of using the less daunting phrase “climate change” in an attempt to overcome the environmental battle amongst Democrats and Republicans. 5   Since President Bush’s term, Luntz remains just one political consultant out of many politicians who has recognized the need to address climate change. In an article from 2019, Luntz proclaimed that political parties aside, the climate crisis affects everyone. Luntz argued that politicians should steer clear of trying to communicate “the complicated science of climate change,” and instead engage voters by explaining how climate change personally impacts citizens with natural disasters such as hurricanes, tornadoes, and forest fires. 6   He even suggested that a shift away from words like “sustainability” would gear Americans towards what they really want: a “cleaner, safer, healthier” environment. 7

The idea of a cleaner and heathier environment remains easier said than done. The Paris Climate Agreement, introduced in 2015, began the United Nations’ “effort to combat global climate change.” 8   This agreement marked a global initiative to “limit global temperature increase in this century to 2 degrees Celsius above preindustrial levels,” while simultaneously “pursuing means to limit the increase to 1.5 degrees.” 9    Every country on earth has joined together in this agreement for the common purpose of saving our planet. 10   So, what could go wrong here? As much as this sounds like a compelling step in the right direction for climate change, President Donald Trump thought otherwise. In June 2017, President Trump announced the withdrawal of the United States from the Paris Agreement with his proclamation of climate change as a “’hoax’ perpetrated by China.” 11   President Trump continued to question the scientific facts behind climate change, remaining an advocate for the expansion of domestic fossil fuel production. 12   He reversed environmental policies implemented by former President Barack Obama to reduce fossil fuel use. 13

Trump’s actions against the Paris Agreement, however, fail to represent the beliefs of Americans as a whole. The majority of American citizens feel passionate about the fight against climate change. To demonstrate their support, some have gone as far as creating initiatives including America’s Pledge and We Are Still In. 14   Although the United States officially exited the Paris Agreement on November 4, 2020, this withdrawal may not survive permanently. 15   According to experts, our new president “could rejoin in as short as a month’s time.” 16   This offers a glimmer of hope.

The Paris Agreement declares that the United States will reduce greenhouse gas emission levels by 26 to 28 percent by the year 2025. 17   As a leader in greenhouse gas emissions, the United States needs to accept the climate crisis for the serious challenge that it presents and work together with other nations. The concept of working coherently with all nations remains rather tricky; however, I remain optimistic. I think we can learn from how other countries have adapted to the increased heating of our planet. During my recent study abroad experience in the United Kingdom, I was struck by Great Britain’s commitment to combating climate change.

Since the United Kingdom joined the Paris Agreement, the country targets a “net-zero” greenhouse gas emission for 2050. 18   This substantial alteration would mark an 80% reduction of greenhouse gases from 1990, if “clear, stable, and well-designed policies are implemented without interruption.” 19   In order to stay on top of reducing emissions, the United Kingdom tracks electricity and car emissions, “size of onshore and offshore wind farms,” amount of homes and “walls insulated, and boilers upgraded,” as well as the development of government policies, including grants for electric vehicles. 20   A strong grip on this data allows the United Kingdom to target necessary modifications that keep the country on track for 2050. In my brief semester in Newcastle, I took note of these significant changes. The city of Newcastle is small enough that many students and faculty are able to walk or bike to campus and nearby essential shops. However, when driving is unavoidable, the majority of the vehicles used are electric, and many British citizens place a strong emphasis on carpooling to further reduce emissions. The United Kingdom’s determination to severely reduce greenhouse emissions is ambitious and particularly admirable, especially as the United States struggles to shy away from its dependence on fossil fuels.

So how can we, as Americans, stand together to combat global climate change? Here are five adjustments Americans can make to their homes and daily routines that can dramatically make a difference:

• Stay cautious of food waste. Studies demonstrate that “Americans throw away up to 40 percent of the food they buy.” 21   By being more mindful of the foods we purchase, opting for leftovers, composting wastes, and donating surplus food to those in need, we can make an individual difference that impacts the greater good. 22   
• Insulate your home. Insulation functions as a “cost-effective and accessible” method to combat climate change. 23   Homes with modern insulation reduce energy required to heat them, leading to a reduction of emissions and an overall savings; in comparison, older homes can “lose up to 35 percent of heat through their walls.” 24   
• Switch to LED Lighting. LED stands for “light-emitting diodes,” which use “90 percent less energy than incandescent bulbs and half as much as compact fluorescents.” 25   LED lights create light without producing heat, and therefore do not waste energy. Additionally, these lights have a longer duration than other bulbs, which means they offer a continuing savings. 26  
• Choose transportation wisely. Choose to walk or bike whenever the option presents itself. If walking or biking is not an option, use an electric or hybrid vehicle which emits less harmful gases. Furthermore, reduce the number of car trips taken, and carpool with others when applicable. 
• Finally, make your voice heard. The future of our planet remains in our hands, so we might as well use our voices to our advantage. Social media serves as a great platform for this. Moreover, using social media to share helpful hints to combat climate change within your community or to promote an upcoming protest proves beneficial in the long run. If we collectively put our voices to good use, together we can advocate for change.

As many of us are stuck at home due to the COVID-19 pandemic, these suggestions are slightly easier to put into place. With numerous “stay-at-home” orders in effect, Americans have the opportunity to make significant achievements for climate change. Personally, I have taken more precautions towards the amount of food consumed within my household during this pandemic. I have been more aware of food waste, opting for leftovers when too much food remains. Additionally, I have realized how powerful my voice is as a young college student. Now is the opportunity for Americans to share how they feel about climate change. During this unprecedented time, our voice is needed now more than ever in order to make a difference.

However, on a much larger scale, the coronavirus outbreak has shed light on reducing global energy consumption. Reductions in travel, both on the roads and in the air, have triggered a drop in emission rates. In fact, the International Energy Agency predicts a 6 percent decrease in energy consumption around the globe for this year alone. 27   This drop is “equivalent to losing the entire energy demand of India.” 28   Complete lockdowns have lowered the global demand for electricity and slashed CO2 emissions. However, in New York City, the shutdown has only decreased carbon dioxide emissions by 10 percent. 29   This proves that a shift in personal behavior is simply not enough to “fix the carbon emission problem.” 30   Climate policies aimed to reduce fossil fuel production and promote clean technology will be crucial steppingstones to ameliorating climate change effects. Our current reduction of greenhouse gas emissions serves as “the sort of reduction we need every year until net-zero emissions are reached around 2050.” 31   From the start of the coronavirus pandemic, politicians came together for the common good of protecting humanity; this demonstrates that when necessary, global leaders are capable of putting humankind above the economy. 32

After researching statistics comparing the coronavirus to climate change, I thought back to the moment the virus reached pandemic status. I knew that a greater reason underlay all of this global turmoil. Our globe is in dire need of help, and the coronavirus reminds the world of what it means to work together. This pandemic marks a turning point in global efforts to slow down climate change. The methods we enact towards not only stopping the spread of the virus, but slowing down climate change, will ultimately depict how humanity will arise once this pandemic is suppressed. The future of our home planet lies in how we treat it right now. 

• “Climate Change: What Do All the Terms Mean?,” BBC News (BBC, May 1, 2019), https://www.bbc.com/news/science-environment-48057733 )
• Ibid. 
• Kate Yoder, “Frank Luntz, the GOP's Message Master, Calls for Climate Action,” Grist (Grist, July 26, 2019), https://grist.org/article/the-gops-most-famous-messaging-strategist-calls-for-climate-action
• Melissa Denchak, “Paris Climate Agreement: Everything You Need to Know,” NRDC, April 29, 2020, https://www.nrdc.org/stories/paris-climate-agreement-everything-you-need-know)
• “Donald J. Trump's Foreign Policy Positions,” Council on Foreign Relations (Council on Foreign Relations), accessed May 7, 2020, https://www.cfr.org/election2020/candidate-tracker/donald-j.-trump?gclid=CjwKCAjw4871BRAjEiwAbxXi21cneTRft_doA5if60euC6QCL7sr-Jwwv76IkgWaUTuyJNx9EzZzRBoCdjsQAvD_BwE#climate and energy )
• David Doniger, “Paris Climate Agreement Explained: Does Congress Need to Sign Off?,” NRDC, December 15, 2016, https://www.nrdc.org/experts/david-doniger/paris-climate-agreement-explained-does-congress-need-sign )
• “How the UK Is Progressing,” Committee on Climate Change, March 9, 2020, https://www.theccc.org.uk/what-is-climate-change/reducing-carbon-emissions/how-the-uk-is-progressing/)
• Ibid.  
• “Top 10 Ways You Can Fight Climate Change,” Green America, accessed May 7, 2020, https://www.greenamerica.org/your-green-life/10-ways-you-can-fight-climate-change )
• Matt McGrath, “Climate Change and Coronavirus: Five Charts about the Biggest Carbon Crash,” BBC News (BBC, May 5, 2020), https://www.bbc.com/news/amp/science-environment-52485712 )

Facts and opinions about climate change

By Richard C. J. Somerville | December 7, 2020

Editor’s note: This article is adapted from a public lecture for the Aquarium of the Pacific in Long Beach, Calif. [1]

When the Bulletin of the Atomic Scientists was founded, climate change science was in its infancy. There were no global climate models, no supercomputers, and no satellite remote-sensing data. Only a few visionaries understood that man-made increases in the amount of carbon dioxide (CO 2 ) might cause large global climate changes. The definitive summary of atmospheric science in the decade after World War II was the Compendium of Meteorology , a large multi-authored volume published in 1951 by the American Meteorological Society. Its article on climate change, written by the distinguished British climatologist C. E. P. Brooks, reflects the prevailing expert opinion of that time.

The article began with this statement:

“In the past hundred years the burning of coal has increased the amount of CO 2 by a measurable amount (from 0.028 to 0.030 per cent), and Callendar (1939) sees in this an explanation of the recent rise in world temperature. But during the past 7,000 years there have been greater fluctuations of temperature without the intervention of man, and there seems to be no reason to regard the recent rise as more than a coincidence. This theory is not considered further.”

It is important to distinguish between facts and opinions. “Everyone is entitled to his own opinion, but not to his own facts.” Daniel Patrick Moynihan , who said that, was a wise and accomplished American politician, sociologist, and diplomat. Like everybody, I know some facts, and I have some opinions. I will first summarize the facts that we have learned from the science of climate change. Then I will give some opinions about what people and governments should do.

I think any rational response to climate change involves first knowing what the facts and evidence are. That is the province of science. There are many indicators measured globally over many decades that show that the Earth’s climate is warming. All the indicators expected to increase in a warming world are increasing, and all those expected to decrease in a warming world are decreasing. It’s definitely warming. It’s not a hoax. We observe it and measure it. The atmosphere is warming. So is the ocean. Sea level is rising. Ice sheets and glaciers and snow cover are shrinking. The amount of water vapor in the atmosphere is increasing. Climate change is real and serious. It’s not a remote threat for the distant future. It’s here and now.

It’s us. We’ve done the detective work. Just as wildfire experts can say whether a fire was caused by lightning, or by a campfire accidentally left burning, or by arson, we can show what is now causing the world to warm. Yes, some past climate change was natural, like ice ages coming and going, but the warming we have observed in recent decades is clearly caused by human activities. The evidence for that is overwhelming.

We now know what paces the beginnings and ends of ice ages. It is slow changes in the Earth’s orbit around the sun, that alter how sunlight is distributed over the surface of the Earth. We understand these changes in the orbit, and they take thousands of years to have an effect. They cannot possibly produce the climate changes that we observe occurring in just a few decades. Similarly, we can rule out other natural processes, such as changes in the energy in sunlight. They are quantitatively too small. Human activities, such as burning coal and oil and natural gas, are the dominant cause of the rapid climate change we now observe.

It hasn’t stopped. The warming is still continuing. We have good estimates of the global average temperature of the Earth’s surface from 1880 until the present; 1880 is about the time when we first had enough good thermometers located in enough places around the Earth to enable us to calculate a meaningful global average. The modern data is the most accurate. During about the last 50 years, from the 1970s until now, we know there has been a warming of about 1 degree Celsius, or 1.8 degrees Fahrenheit. All the warmest years on record are recent years.

The heat is mainly in the sea. Over 90 percent of the heat added to the climate system is in the oceans. How do we measure the heat stored in the ocean? That’s a good question, and it has a fascinating answer.

We now measure this increase in ocean heat content from an array of about 4,000 autonomous floats deployed throughout the world ocean under an international program called Argo . They have no engines and no propellers, but they move with the ocean currents at a depth of 1,000 meters, which is about 10 football fields. That’s where they are usually parked, and they are programmed to periodically sink another 1,000 meters lower and then rise to the surface while measuring quantities such as water temperature and salinity. They rise and sink by changing their volume. This is accomplished by pumping fluid into or out of a bladder on the float.

The floats store the measurements, and then, when they are on the surface, they locate by GPS and transmit the stored data via satellites to scientists. The change in float locations between one transmission and the next provides information on the currents at the depth where the floats were parked. As their batteries fail, the floats end their useful lives and must be replaced by new floats. The Argo floats have revolutionized our ability to observe the oceans. Argo data are available to everyone for free in near real time. New floats, allowing sampling to much greater depths, are now being developed.

Sea level is rising globally. We measure it from altimeters on satellites. There has been a rise of about 100 millimeters, which is about 4 inches, over the last 30 years or so. The rate of sea level rise is increasing too. Future sea level rise will be much greater than past sea level rise. The sea level rise is different at different locations on the Earth. Local sea level is affected by whether the land at that location is rising or sinking, and also by ocean currents, tides and other factors.

Ice is shrinking. Ice sheets on Greenland and Antarctica and almost every glacier worldwide are all shrinking. We know this from satellite missions called GRACE (the Gravity Recovery and Climate Experiment ). These satellites determine the mass of the ice accurately by measuring the effect of the ice sheet on the Earth’s gravity. The technology of the GRACE missions involves two satellites in the same orbit which have a means of measuring the distance between the two satellites extremely accurately. This distance changes when gravity varies, which occurs when passing over ice sheets, and measuring the tiny change in the inter-satellite distance allows scientists to determine the mass of the ice.

Carbon dioxide absorbed by the ocean makes it more nearly acidic. That can affect the marine ecosystem and the food chain. The ocean absorbs some of the CO 2 that we emit into the atmosphere. Measurements show that the acidity parameter called pH is decreasing. Seawater is slightly basic (its pH is greater than 7), and we observe a shift towards neutral conditions (pH = 7), rather than to truly acidic conditions (pH less than 7).

Carbon dioxide amounts in the atmosphere, because of human activities, are now about 45 percent higher than they were in the early 1800s. We have good measurements of atmospheric CO 2 amounts over the last 800,000 years. These data come from analyzing fossil air trapped in ice in Greenland and Antarctica. They reveal large variations in CO 2 amounts, associated with ice ages starting and ending. Orbital variations pace the ice ages, causing the CO 2 amounts to change, and initiating a feedback that increases the magnitude of the temperature change.

The amount of carbon dioxide in the atmosphere now is the highest it has been in millions of years. The atmospheric CO 2 amounts in the even more distant geological past, many million years ago, sometimes have been even higher than at present, but the world was a very different place then, which was long before any human beings existed.

Cumulative emissions of carbon dioxide set the amount of warming. The warming caused by CO 2 in recent decades is, to a good approximation, just linearly proportional to the total cumulative amount of carbon emitted into the atmosphere. We do not know exactly how much added CO2 will produce how much warming—that is, the climate sensitivity question—but we can estimate a range of possible answers to this question, constrained by different kinds of observations. For the middle of the range, 1 trillion metric tons of carbon emitted produces a warming of about 2 degrees Celsius above the temperatures of the early 1800s. We have already emitted about half of this amount. At present, the warming we observe is caused by CO 2 plus several other heat-trapping substances that human activities have also added to the atmosphere. The amounts in the atmosphere of these other substances will decrease rapidly when and if their sources are eliminated, but some of the carbon dioxide will remain in the atmosphere for thousands of years. Because of the difference in the amount of time that different heat-trapping substances stay in the atmosphere, carbon dioxide is truly the key “control knob” for climate.

Reducing emissions of carbon dioxide and other heat-trapping substances will limit the warming. We can estimate the cumulative amount of carbon emitted that would give us a good chance of limiting warming to 2 degrees Celsius (that’s 3.6 degrees Fahrenheit) above the pre-industrial temperatures of the early 1800s. This is the warming target endorsed by the Paris Agreement of 2015. If emissions had peaked and began to decline several decades ago, then emissions reductions could be gradual, and by 2050 emissions would not yet need to have entirely stopped. Because emissions are still increasing, drastic emissions reductions need to occur quickly and reach zero by 2040.

“Negative emissions,” meaning removing some carbon dioxide from the air, are likely to be necessary. This fact illustrates the urgency of acting. Finding a way of removing some of the carbon dioxide is one approach to geoengineering. Here by “geoengineering” we mean the intentional modification of the climate system with the goal of reducing or mitigating climate change. However, nobody has yet demonstrated a way of economically removing large amounts of carbon dioxide from the atmosphere.

The longer we wait before acting, the more drastic the action has to be. The result of failing to act is to increase the likelihood of dangerous climate change.

Because it takes so long for the carbon dioxide in the atmosphere to decrease, climate change will last for centuries. After emissions completely stop, the amount of carbon dioxide in the atmosphere decreases only slowly for several centuries, and about 25 percent of it remains in the atmosphere for the next 10,000 years or so. The science relevant to this topic is not simple. Several complex processes for carbon removal are involved. The key take-away message is that the climate change caused by adding carbon dioxide to the atmosphere can have very long-lasting effects.

The conclusions I have just recounted are facts. They are fundamental findings from extensive scientific research. They are all well-supported by abundant evidence.

The science is never complete. There is always more to learn. But the science that we have now is already good enough to help us make wise decisions. The many unknowns in the science, such as exactly how fast the Antarctic ice sheet will shrink or exactly how El Niño might be affected, are not the biggest unknowns about future climate. The biggest unknown about future climate is human behavior. Everything depends on what people and their governments do.

The scientific consensus is overwhelming. Climate change is already happening, here and now. About 97 percent of climate experts—the scientists who are most active in carrying out and publishing research on climate change—agree that the observed recent warming is real and serious and overwhelmingly human-caused, and that it will become even more serious unless we make big changes in how we generate energy. Nevertheless, some people remain unconvinced. They continue to repeat climate myths and falsehoods.

People often ask me, “I’m only one person. What can I do about climate change?” Here is my answer. We need to persuade more people that this problem is serious. Governments tend to respond when enough people become concerned, and when they vote their concerns. I urge everyone to engage with people you may know—family, friends, colleagues—who don’t accept the fundamental findings of climate science. Explain to them the facts you have learned about our changing climate. Listen to them respectfully and carefully. Be alert to the common climate myths and falsehoods that they may think are true. If you see something, say something. Have a civil conversation. Have many conversations. In their hearts, almost all of us would surely agree that everybody is entitled to his own opinions, but not to his own facts. And it is science that supplies the facts about climate change.

We humans have become the dominant actors in causing the rapid climate change we now observe. Human actions now overwhelm all the natural processes. This may seem counter-intuitive, but it’s true. You and I, and all the people who are alive today, now have our hands on the thermostat that controls the climate of our children and grandchildren. Metaphors can be superb communication tools. The thermostat is a powerful metaphor.

Think about medical metaphors. Here are a few: We climate scientists are planetary physicians. Climate science and medical science will both always be imperfect and incomplete, but both are already very useful.

When your doctor tells you to stop smoking and lose weight and exercise more, you don’t argue with her. You don’t call her a radical alarmist. You don’t ask her to name the date when you will have a heart attack.

Physicians have advanced academic credentials and many years of training and experience. We climate scientists have the same. We’re not conspiring to fool people. Do you really think your doctor is a crook? She’s not. Neither are we.

A fever of only a few degrees can indicate a serious disease. Global warming is just a symptom of planetary ill health, like a fever.

Prevention is better than cure. Quitting smoking, like quitting using fossil fuels, is not easy to do. And the main benefits of quitting come in the long-term future.

Choosing to have major surgery involves cost and risk. People know that choosing to do nothing also has costs and risks.

The laws of climate science and medical science are all immune from political tampering. You can’t fool Mother Nature. Mother Nature always bats last.

Here’s an effective metaphor. Imagine you are watching a major-league baseball game. The slugger who is thought to be on performance-enhancing drugs hits a home run. The person next to you asks, did the steroids cause it? That’s really the wrong question. You can’t be sure they caused it, because he was already a big-league slugger when he was clean. And even with the drugs, he can still strike out now and then. But at the end of the season, you see in his statistics that he hit more homers than he used to. The steroids increase the odds of home runs. Climate is the statistics of weather, and carbon dioxide is the steroids of climate. [2] It changes the odds. The odds are higher now for all sorts of extreme weather, because climate change has altered the environment in which all weather occurs.

This metaphor works for other sports too. For example, baseball isn’t popular in France, but bicycle racing is very popular there, and French people know that a bike racer on drugs won’t win every race, but the drugs do change the odds and increase his probability of winning.

The main barriers to action on climate change are a lack of widespread political will and a lack of wise and inspiring leadership. Science can help to inform policy, but only concerned people and responsive, capable governments can first decide what policies are best, and then implement them. Today, despite a strong scientific consensus, climate change is controversial politically.

We do not have to accept a future with devastating climate damage and disruption. If we continue to use more and more fossil fuels to generate the world’s energy, we will be sentencing our children and grandchildren to many centuries with a severely damaged climate and great suffering. In your conversations, try to help people understand that this bleak future is entirely preventable.

Faced with these threats, almost all the nations of the world agreed in Paris in late 2015 to limit the warming to a specific maximum amount. That amount is 2 degrees Celsius, or 3.6 degrees Fahrenheit, above the average global temperature in the early 1800s, before human activities began to have a large effect

After Paris, is the glass half-empty or half-full? I am guardedly optimistic, for these reasons:

• World leaders are now engaged; at least almost all of them are.
• Emissions of heat-trapping gases have begun to decline in some places.
• Solar and wind energy are getting cheaper every year.
• Renewable energy use is increasing rapidly.
• Many corporations are now acting to reduce emissions.
• State and local governments in the United States are acting too, despite federal inaction.
• Many other countries are showing rapid progress.

Recent polling shows that in the United States, many more people accept the science and are very concerned about global warming or climate change than was the case only a few years ago. However, the issue has become extremely partisan. Recent polls show that the substantial increase in the number of Americans calling climate change a top priority has been limited to the Democratic side of the political spectrum. However, about 80 percent of Republicans, including virtually the entire leadership of the Republican party, have not changed their minds and still reject the science. We have a long way to go. I think we should keep climate change science separated from climate change policy.

There is no silver bullet that solves all the challenges of climate change, but there is a lot of silver buckshot, including increased energy efficiency and energy conservation, and much more use of sun, wind and water to provide the energy the world needs. These renewable resources are widely available now and already cost-competitive with fossil fuels. We have the technology, and it is improving. In the United States, even without energetic action by the federal government, I am guardedly optimistic.

Market forces now favor carbon-free energy. Coal companies are going bankrupt. Solar and wind energy without subsidies are in many cases already cheaper than fossil fuels. Electric vehicles are happening fast. Much energy policy in the US is set at state and local levels, not in Washington.

Always remember why we want to have conversations about climate change science. We want to inform people. We want to motivate them. We want them to act.

Research suggests that messages that may invoke fear or dismay are better received if they also include hope. We should include positive messages about our ability to solve the problem. We can explain that future climate is in our hands.

Politics and priorities and values do have a role to play in deciding which actions are best, but any rational policy begins by accepting the science. People are entitled to their own opinions, but not to their own facts.

This article is being written in 2020 during the global coronavirus pandemic, and I have a few gentle words to say about some climate change lessons that we might learn from the pandemic now gripping the entire world.

One obvious point is that climate change science, like coronavirus epidemiology, is incomplete, still developing but already extremely useful. In both domains, we have learned we can trust scientists more than politicians or pundits or anybody else who is not really an expert on the science of the subject, whether the subject is climate change or infectious diseases. We have also learned that the challenges in both climate change and the pandemic are global. The entire world is affected. The solutions have to be global too.

The pandemic also illustrates the wisdom of the statement that, “Everybody is entitled to his own opinions, but not to his own facts.” The facts about climate change, and about COVID-19, are objective truth, and they should be the same for everybody, regardless of people’s ideology or politics. When it comes to making policy, sound science can inform wise policy. However, policy can also depend on many other factors, such as people’s priorities, their convictions about economics, what they regard as the proper role of governments, their risk tolerance, and, of course, public opinion. That’s true for meeting the challenge of climate change, just as for meeting the challenge of COVID-19.

The pandemic reminds us how valuable science and scientists are. The recent discussions in the news—such as about how clinical trials of drugs and vaccines work—are very educational. The medical scientists who develop new medicines do their best to make sure they are safe and effective, and they won’t release them for widespread use to the public until they are absolutely convinced of that. They are real experts and are very careful.

So are climate scientists.

Tony Fauci, who has often been on television recently in the United States, is a good example of a person who is a real expert on pandemics. He says simply, “I’m a physician and a scientist.” People get that. When Fauci speaks to the public, he is not trying to be popular or make people happy or brag about himself or make money. He is just telling people the facts that scientists have discovered, and he describes these facts in a way that is honest and transparent and understandable. He has spent his entire career accumulating expertise and experience and wisdom about infectious diseases and pandemics. People should trust him, and polls show that the great majority of people do trust him. Science is absolutely essential. That’s true for pandemics.

It’s also true for climate change.

Like many interested people, I watched Warren Buffett’s 2020 Berkshire Hathaway stockholders meeting online. Warren Buffett, the brilliant investor and one of the richest people in the world, agrees with me. Here’s what he said:

“I think, personally I feel extraordinarily good about being able to listen to Dr. Fauci, who I had never heard of a year ago. But I think we’re very, very fortunate as a country to have somebody at 79 years of age who appears to be able to work 24 hours a day and keep a good humor about him and communicate in a very, very straightforward matter about fairly complex subjects and tell you when he knows something and when he doesn’t know something. So, I’m not going to talk about any political figures at all or our politics generally this afternoon, but I do feel that I owe a huge debt of gratitude to Dr. Fauci for educating and informing me, actually along with my friend Bill Gates, too, as to what’s going on. I know I get it from a straight shooter when I get it from either one of those. So, thank you Dr. Fauci.”

[1] See https://youtu.be/DmUWPn6GCEg

[2] See https://youtu.be/MW3b8jSX7ec

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Keywords: Aquarium of the Pacific , GRACE , Gravity Recovery and Climate Experiment , climate change facts , climate change metaphors Topics: Climate Change , Multimedia

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I have difficulty putting much stock in the opinion of a scientist who only points to CO2 emissions from fossil fuels as the cause of climate change and fails to mention deforestation and shrinking of mangroves around the world.

Richard C. J. Somerville

Richard C. J. Somerville is an internationally recognized climate scientist. He has been a professor at the Scripps Institution of Oceanography at... Read More

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Century of Science: Theme

Our climate change crisis

The climate change emergency.

Even in a world increasingly battered by weather extremes, the summer 2021 heat wave in the Pacific Northwest stood out. For several days in late June, cities such as Vancouver, Portland and Seattle baked in record temperatures that killed hundreds of people. On June 29 Lytton, a village in British Columbia, set an all-time heat record for Canada, at 121° Fahrenheit (49.6° Celsius); the next day, the village was incinerated by a wildfire.

Within a week, an international group of scientists had analyzed this extreme heat and concluded it would have been virtually impossible without climate change caused by humans. The planet’s average surface temperature has risen by at least 1.1 degree Celsius since preindustrial levels of 1850–1900 — because people are loading the atmosphere with heat-trapping gases produced during the burning of fossil fuels, such as coal and gas, and from cutting down forests.

A little over 1 degree of warming may not sound like a lot. But it has already been enough to fundamentally transform how energy flows around the planet. The pace of change is accelerating, and the consequences are everywhere. Ice sheets in Greenland and Antarctica are melting, raising sea levels and flooding low-lying island nations and coastal cities. Drought is parching farmlands and the rivers that feed them. Wildfires are raging. Rains are becoming more intense, and weather patterns are shifting .

The roots of understanding this climate emergency trace back more than a century and a half. But it wasn’t until the 1950s that scientists began the detailed measurements of atmospheric carbon dioxide that would prove how much carbon is pouring from human activities. Beginning in the 1960s, researchers began developing comprehensive computer models that now illuminate the severity of the changes ahead.

Global average temperature change, 1850–2021

Long-term climate datasets show that Earth’s average surface temperature (combined land and ocean) has increased by more than 1 degree Celsius since preindustrial times. Temperature change is the difference from the 1850–1900 average.

Today we know that climate change and its consequences are real, and we are responsible. The emissions that people have been putting into the air for centuries — the emissions that made long-distance travel, economic growth and our material lives possible — have put us squarely on a warming trajectory . Only drastic cuts in carbon emissions, backed by collective global will, can make a significant difference.

“What’s happening to the planet is not routine,” says Ralph Keeling, a geochemist at the Scripps Institution of Oceanography in La Jolla, Calif. “We’re in a planetary crisis.” — Alexandra Witze

Tracking a Greenland glacier

The calving front of Greenland’s Helheim Glacier, which flows toward the sea where it crumbles into icebergs, held roughly the same position from the 1970s until 2001 (left, the calving front is to the far right of the image). But by 2005 (right), it had retreated 7.5 kilometers toward its source. 

The first climate scientists

One day in the 1850s, Eunice Newton Foote, an amateur scientist and women’s rights activist living in upstate New York, put two glass jars in sunlight. One contained regular air — a mix of nitrogen, oxygen and other gases including carbon dioxide — while the other contained just CO 2 . Both had thermometers in them. As the sun’s rays beat down, Foote observed that the jar of CO 2 alone heated more quickly, and was slower to cool, than the one containing plain air.

The results prompted Foote to muse on the relationship between CO 2 , the planet and heat. “An atmosphere of that gas would give to our earth a high temperature,” she wrote in an 1856 paper summarizing her findings .

Three years later, working independently and apparently unaware of Foote’s discovery, Irish physicist John Tyndall showed the same basic idea in more detail. With a set of pipes and devices to study the transmission of heat, he found that CO 2 gas, as well as water vapor, absorbed more heat than air alone. He argued that such gases would trap heat in Earth’s atmosphere, much as panes of glass trap heat in a greenhouse, and thus modulate climate. “As a dam built across a river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial rays, produces a local heightening of the temperature at the Earth’s surface,” he wrote in 1862.

Today Tyndall is widely credited with the discovery of how what are now called greenhouse gases heat the planet, earning him a prominent place in the history of climate science. Foote faded into relative obscurity — partly because of her gender, partly because her measurements were less sensitive. Yet their findings helped kick off broader scientific exploration of how the composition of gases in Earth’s atmosphere affects global temperatures.

Carbon floods in

Humans began substantially affecting the atmosphere around the turn of the 19th century, when the Industrial Revolution took off in Britain. Factories burned tons of coal; fueled by fossil fuels, the steam engine revolutionized transportation and other industries. In the decades since, fossil fuels including oil and natural gas have been harnessed to drive a global economy. All these activities belch gases into the air.

Yet Svante Arrhenius, a Swedish physical chemist, wasn’t worried about the Industrial Revolution when he began thinking in the late 1800s about changes in atmospheric CO 2 levels. He was instead curious about ice ages — including whether a decrease in volcanic eruptions, which can put CO 2 into the atmosphere, would lead to a future ice age. Bored and lonely in the wake of a divorce, Arrhenius set himself to months of laborious calculations involving moisture and heat transport in the atmosphere at different zones of latitude. In 1896 he reported that halving the amount of CO 2 in the atmosphere could indeed bring about an ice age — and that doubling CO 2 would raise global temperatures by around 5 to 6 degrees C.

It was a remarkably prescient finding for work that, out of necessity, had simplified Earth’s complex climate system down to just a few variables. Today, estimates for how much the planet will warm through a doubling of CO 2 — a measure known as climate sensitivity — range between 1.5 degrees and 4.5 degrees Celsius. (The range remains broad in part because scientists now incorporate their understanding of many more planetary feedbacks than were recognized in Arrhenius’ day.)  

But Arrhenius’ findings didn’t gain much traction with other scientists at the time. The climate system seemed too large, complex and inert to change in any meaningful way on a timescale that would be relevant to human society. Geologic evidence showed, for instance, that ice ages took thousands of years to start and end. What was there to worry about? And other laboratory experiments — later shown to be flawed — appeared to indicate that changing levels of CO 2 would have little impact on heat absorption in the atmosphere. Most scientists aware of the work came to believe that Arrhenius had been proved wrong.

One researcher, though, thought the idea was worth pursuing. Guy Stewart Callendar, a British engineer and amateur meteorologist, had tallied weather records over time, obsessively enough to determine that average temperatures were increasing at 147 weather stations around the globe. In 1938, in a paper in a Royal Meteorological Society journal , he linked this temperature rise to the burning of fossil fuels. Callendar estimated that fossil fuel burning had put around 150 billion metric tons of CO 2 into the atmosphere since the late 19th century.

Like many of his day, Callendar didn’t see global warming as a problem. Extra CO 2 would surely stimulate plants to grow and allow crops to be farmed in new regions. “In any case the return of the deadly glaciers should be delayed indefinitely,” he wrote. But his work revived discussions tracing back to Tyndall and Arrhenius about how the planetary system responds to changing levels of gases in the atmosphere. And it began steering the conversation toward how human activities might drive those changes.

When World War II broke out the following year, the global conflict redrew the landscape for scientific research. Hugely important wartime technologies, such as radar and the atomic bomb, set the stage for “big science” studies that brought nations together to tackle high-stakes questions of global reach. And that allowed modern climate science to emerge.

The Keeling curve and climate change

One major postwar effort was the International Geophysical Year, an 18-month push in 1957–1958 that involved a wide array of scientific field campaigns including exploration in the Arctic and Antarctica. Climate change wasn’t a high research priority during the IGY, but some scientists in California, led by Roger Revelle of the Scripps Institution of Oceanography in La Jolla, used the funding influx to begin a project they’d long wanted to do. The goal was to measure CO 2 levels at different locations around the world, accurately and consistently.

The job fell to geochemist Charles David Keeling, who put ultraprecise CO 2 monitors in Antarctica and on the Hawaiian volcano of Mauna Loa. Funds soon ran out to maintain the Antarctic record, but the Mauna Loa measurements continued. Thus was born one of the most iconic datasets in all of science — the “Keeling curve,” which tracks the rise of atmospheric CO 2 . When Keeling began his measurements in 1958, CO 2 made up 315 parts per million of the global atmosphere. Within just a few years it became clear that the number was increasing year by year. Because plants take up CO 2 as they grow in spring and summer and release it as they decompose in fall and winter, CO 2 concentrations rose and fell each year in a sawtooth pattern — but superimposed on that pattern was a steady march upward.  

Monthly average CO 2 concentrations at Mauna Loa Observatory

Atmospheric carbon dioxide measurements collected continuously since 1958 at Mauna Loa volcano in Hawaii show the rise due to human activities. The visible sawtooth pattern is due to seasonal plant growth: Plants take up CO 2 in the growing seasons, then release it as they decompose in fall and winter.

“The graph got flashed all over the place — it was just such a striking image,” says Ralph Keeling, who is Charles David Keeling’s son. Over the years, as the curve marched higher, “it had a really important role historically in waking people up to the problem of climate change.” The Keeling curve has been featured in countless earth science textbooks, congressional hearings and in Al Gore’s 2006 documentary on climate change, An Inconvenient Truth . Each year the curve keeps going up: In 2016 it passed 400 ppm of CO 2 in the atmosphere, as measured during its typical annual minimum in September. In 2021, the annual minimum was 413 ppm. (Before the Industrial Revolution, CO 2 levels in the atmosphere had been stable for centuries at around 280 ppm.)

Around the time that Keeling’s measurements were kicking off, Revelle also helped develop an important argument that the CO 2 from human activities was building up in Earth’s atmosphere. In 1957 he and Hans Suess, also at Scripps at the time, published a paper that traced the flow of radioactive carbon through the oceans and the atmosphere. They showed that the oceans were not capable of taking up as much CO 2 as previously thought; the implication was that much of the gas must be going into the atmosphere instead. “Human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future,” Revelle and Suess wrote in the paper. It’s one of the most famous sentences in earth science history.

“Human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.”

Here was the insight underlying modern climate science: Atmosheric CO 2 is increasing, and humans are causing the buildup. Revelle and Suess became the final piece in a puzzle dating back to Svante Arrhenius and John Tyndall.

“I tell my students that to understand the basics of climate change, you need to have the cutting-edge science of the 1860s, the cutting-edge math of the 1890s and the cutting-edge chemistry of the 1950s,” says Joshua Howe, an environmental historian at Reed College in Portland, Ore.

Environmental awareness grows

As this scientific picture began to emerge in the late 1950s, Science News was on the story. A March 1, 1958 article in Science News Letter , “Weather May Be Warming,” described a warm winter month in the Northern Hemisphere. It posits three theories, including that “carbon dioxide poured into the atmosphere by a booming industrial civilization could have caused the increase. By burning up about 100 billion tons of coal and oil since 1900, man himself may be changing the climate.” By 1972, the magazine was reporting on efforts to expand global atmospheric greenhouse gas monitoring beyond Keeling’s work; two years later, the U.S. National Oceanic and Atmospheric Administration launched its own CO 2 monitoring network, now the biggest in the world.

Environmental awareness on other issues grew in the 1960s and 1970s. Rachel Carson catalyzed the modern U.S. environmental movement in 1962 when she published a magazine series and then a book, Silent Spring , condemning the pesticide DDT for its ecological impacts. 1970 saw the celebration of the first Earth Day , in the United States and elsewhere, and in India in 1973 a group of women led a series of widely publicized protests against deforestation. This Chipko movement explicitly linked environmental protection with protecting human communities, and helped seed other environmental movements.

The fragility of global energy supplies was also becoming more obvious through the 1970s. The United States, heavily dependent on other countries for oil imports, entered a gas shortage in 1973–74 when Arab members of the Organization of the Petroleum Exporting Countries cut off oil supplies because of U.S. government support for Israel. The shortage prompted more people to think about the finiteness of natural resources and the possibility of overtaxing the planet. — Alexandra Witze

Climate change evidence piles up

Observational data collected throughout the second half of the 20th century helped researchers gradually build their understanding of how human activities were transforming the planet. “It was a sort of slow accretion of evidence and concern,” says historian Joshua Howe of Reed College.

Environmental records from the past, such as tree rings and ice cores, established that the current changes in climate are unusual compared with the recent past. Yet such paleoclimatology data also showed that climate has changed quickly in the deep past — driven by triggers other than human activity, but with lessons for how abrupt planetary transformations can be.

Ice cores pulled from ice sheets, such as that atop Greenland, offer some of the most telling insights for understanding past climate change. Each year snow falls atop the ice and compresses into a fresh layer of ice representing climate conditions at the time it formed. The abundance of certain forms, or isotopes, of oxygen and hydrogen in the ice allows scientists to calculate the temperature at which it formed, and air bubbles trapped within the ice reveal how much carbon dioxide and other greenhouse gases were in the atmosphere at that time. So drilling down into an ice sheet is like reading the pages of a history book that go back in time the deeper you go.

Scientists began reading these pages in the early 1960s, using ice cores drilled at a U.S. military base in northwest Greenland . Contrary to expectations that past climates were stable, the cores hinted that abrupt climate shifts had happened over the last 100,000 years. By 1979, an international group of researchers was pulling another deep ice core from a second location in Greenland — and it, too, showed that abrupt climate change had occurred in the past. In the late 1980s and early 1990s a pair of European- and U.S.-led drilling projects retrieved even deeper cores from near the top of the ice sheet, pushing the record of past temperatures back a quarter of a million years.

Together with other sources of information, such as sediment cores drilled from the seafloor and molecules preserved in ancient rocks, the ice cores allowed scientists to reconstruct past temperature changes in extraordinary detail. Many of those changes happened alarmingly fast. For instance, the climate in Greenland warmed abruptly more than 20 times in the last 80,000 years, with the changes occurring in a matter of decades. More recently, a cold spell that set in around 13,000 years ago suddenly came to an end around 11,500 years ago — and temperatures in Greenland rose 10 degrees Celsius in a decade.

Evidence for such dramatic climate shifts laid to rest any lingering ideas that global climate change would be slow and unlikely to occur on a timescale that humans should worry about. “It’s an important reminder of how ‘tippy’ things can be,” says Jessica Tierney, a paleoclimatologist at the University of Arizona in Tucson.

More evidence of global change came from Earth-observing satellites, which brought a new planet-wide perspective on global warming beginning in the 1960s. From their viewpoint in the sky, satellites have measured the steady rise in global sea level — currently 3.4 millimeters per year and accelerating, as warming water expands and as ice sheets melt — as well as the rapid decline in ice left floating on the Arctic Ocean each summer at the end of the melt season. Gravity-sensing satellites have ‘weighed’ the Antarctic and Greenlandic ice sheets from above since 2002, reporting that more than 400 billion metric tons of ice are lost each year.

Temperature observations taken at weather stations around the world also confirm that we are living in the hottest years on record. The 10 warmest years since record keeping began in 1880 have all occurred since 2005. And nine of those 10 have come since 2010.

What’s more, extreme weather is hammering the planet more and more frequently. That 2021 heat wave in the Pacific Northwest, for instance, is just a harbinger of what’s to come. — Alexandra Witze

Worrisome predictions from climate models

By the 1960s, there was no denying that the planet was warming. But understanding the consequences of those changes — including the threat to human health and well-being — would require more than observational data. Looking to the future depended on computer simulations: complex calculations of how energy flows through the planetary system. Such models of the climate system have been crucial to developing projections for what we can expect from greenhouse warming.

A first step in building climate models was to connect everyday observations of weather to the concept of forecasting future climate. During World War I, the British mathematician Lewis Fry Richardson imagined tens of thousands of meteorologists working to forecast the weather, each calculating conditions for a small part of the atmosphere but collectively piecing together a global forecast. Richardson published his work in 1922, to reviews that called the idea “of almost quixotic boldness.”

But it wasn’t until after World War II that computational power turned Richardson’s dream into reality. In the wake of the Allied victory, which relied on accurate weather forecasts for everything from planning D-Day to figuring out when and where to drop the atomic bombs, leading U.S. mathematicians acquired funding from the federal government to improve predictions. In 1950 a team led by Jule Charney, a meteorologist at the Institute for Advanced Study in Princeton, N.J., used the ENIAC, the first general-purpose, programmable electronic computer, to produce the first computer-driven regional weather forecast . The forecasting was slow and rudimentary, but it built on Richardson’s ideas of dividing the atmosphere into squares, or cells, and computing the weather for each of those. With the obscure title “Numerical integration of the barotropic vorticity equation,” the paper reporting the results set the stage for decades of climate modeling to follow.

By 1956 Norman Phillips, a member of Charney’s team, had produced the world’s first general circulation model, which captured how energy flows between the oceans, atmosphere and land. Phillips ran the calculations on a computer with just 5 kilobytes of memory, yet it was able to reproduce monthly and seasonal patterns in the lower atmosphere. That meant scientists could begin developing more realistic models of how the planet responds to factors such as increasing levels of greenhouse gases. The field of climate modeling was born.

The work was basic at first, because early computers simply didn’t have much computational power to simulate all aspects of the planetary system. “People thought that it was stupid to try to study this greenhouse-warming issue by three-dimensional model[s], because it cost so much computer time,” meteorologist Syukuro Manabe told physics historian Spencer Weart in a 1989 oral history .

Climate models have predicted how much ice the Ilulissat region of the Greenland ice sheet might lose by 2300 based on different scenarios for greenhouse gas emissions. The models are compared to 2008 (first image). In a best-case scenario, in which emissions peak by mid-century, the speed at which the glacier is sending ice out into the ocean is much lower (second image) than with a worst-case scenario, in which emissions rise at a high rate (third image).

An important breakthrough came in 1967, when Manabe and Richard Wetherald — both at the Geophysical Fluid Dynamics Laboratory in Princeton, a lab born from Charney’s group — published a paper in the Journal of the Atmospheric Sciences that modeled connections between Earth’s surface and atmosphere and calculated how changes in carbon dioxide would affect the planet’s temperature. Manabe and Wetherald were the first to build a computer model that captured the relevant processes that drive climate , and to accurately simulate how the Earth responds to those processes. (Manabe shared the 2021 Nobel Prize in physics for his work on climate modeling; Wetherald died in 2011.)

The rise of climate modeling allowed scientists to more accurately envision the impacts of global warming. In 1979, Charney and other experts met in Woods Hole, Mass., to try to put together a scientific consensus on what increasing levels of CO 2 would mean for the planet. They analyzed climate models from Manabe and from James Hansen of NASA. The resulting “Charney report” concluded that rising CO 2 in the atmosphere would lead to additional and significant climate change. The ocean might take up much of that heat, the scientists wrote — but “it appears that the warming will eventually occur, and the associated regional climatic changes so important to the assessment of socioeconomic consequence may well be significant.”

In the decades since, climate modeling has gotten increasingly sophisticated . Scientists have drawn up a variety of scenarios for how carbon emissions might change in the future, depending on the stringency of emissions cuts. Modelers use those scenarios to project how climate and weather will change around the globe, from hotter croplands in China to melting glaciers in the Himalayas. Climate simulations have also allowed researchers to identify the fingerprints of human impacts on extreme weather that is already happening, by comparing scenarios that include the influence of human activities with those that do not.

And as climate science firmed up and the most dramatic consequences became clear, the political battles raged. — Alexandra Witze

Climate science meets politics

With the development of climate science tracing back to the early Cold War, perhaps it shouldn’t be a surprise that the science of global warming became enmeshed in broader societal and political battles. A complex stew of political, national and business interests mired society in debates about the reality of climate change, and what to do about it, decades after the science became clear that humans are fundamentally altering the planet’s atmosphere.

Society has pulled itself together before to deal with global environmental problems, such as the Antarctic ozone hole. In 1974 chemists Mario Molina and F. Sherwood Rowland, both of the University of California, Irvine, reported that chlorofluorocarbon chemicals, used in products such as spray cans and refrigerants, caused a chain of reactions that gnawed away at the atmosphere’s protective ozone layer . The resulting ozone hole, which forms over Antarctica every spring, allows more ultraviolet radiation from the sun to make it through Earth’s atmosphere and reach the surface, where it can cause skin cancer and eye damage.

Governments ultimately worked under the auspices of the United Nations to craft the 1987 Montreal Protocol, which strictly limited the manufacture of chlorofluorocarbons . In the years following, the ozone hole began to heal. But fighting climate change would prove to be far more challenging. Chlorofluorocarbons were a suite of chemicals with relatively limited use and for which replacements could be found without too much trouble. But the greenhouse gases that cause global warming stem from a wide variety of human activities, from energy development to deforestation. And transforming entire energy sectors to reduce or eliminate carbon emissions is much more difficult than replacing a set of industrial chemicals.

In 1980, though, researchers took an important step toward banding together to synthesize the scientific understanding of climate change and bring it to the attention of international policy makers. It started at a small scientific conference in Villach, Austria. There, experts met under the auspices of the World Meteorological Organization, the International Council of Scientific Unions and the United Nations Environment Program to discuss the seriousness of climate change. On the train ride home from the meeting, Swedish meteorologist Bert Bolin talked with other participants about how a broader, deeper and more international analysis was needed. In 1985, a second conference was held at Villach to highlight the urgency, and in 1988, the Intergovernmental Panel on Climate Change, the IPCC, was born. Bolin was its first chairperson.

The IPCC became a highly influential and unique body. It performs no original scientific research; instead, it synthesizes and summarizes the vast literature of climate science for policy makers to consider — primarily through massive reports issued every couple of years. The first IPCC report , in 1990, predicted that the planet’s global mean temperature would rise more quickly in the following century than at any point in the last 10,000 years, due to increasing greenhouse gases in the atmosphere. Successive IPCC reports showed more and more confidence in the link between greenhouse emissions and rising global temperatures — and explored how society might mitigate and adapt to coming changes.

IPCC reports have played a key role in providing scientific information for nations discussing how to stabilize greenhouse gas concentrations. This process started with the Rio Earth Summit in 1992 , which resulted in the U.N. Framework Convention on Climate Change. Annual U.N. meetings to tackle climate change led to the first international commitments to reduce emissions, the Kyoto Protocol of 1997. Under it, developed countries committed to reduce emissions of CO 2 and other greenhouse gases. By 2007 the IPCC declared that the reality of climate warming is “unequivocal ”; the group received the Nobel Peace Prize that year along with Al Gore for their work on climate change.

The IPCC process ensured that policy makers had the best science at hand when they came to the table to discuss cutting emissions. “If you go back and look at the original U.N. framework on climate change, already you see the core of the science represented there,” says Rachel Cleetus, a climate policy expert with the Union of Concerned Scientists in Cambridge, Mass. Of course, nations did not have to abide by that science — and they often didn’t.

Throughout the 2000s and 2010s, international climate meetings discussed less hard-core science and more issues of equity. Countries such as China and India pointed out that they needed energy to develop their economies, and that nations responsible for the bulk of emissions through history, such as the United States, needed to lead the way in cutting greenhouse gases. Meanwhile, residents of some of the most vulnerable nations, such as low-lying islands that are threatened by sea level rise, gained visibility and clout at international negotiating forums. “The issues around equity have always been very uniquely challenging in this collective action problem,” says Cleetus.

By 2015, the world’s nations had made some progress on the emissions cuts laid out in the Kyoto Protocol, but it was still not enough to achieve substantial global reductions. That year, a key U.N. climate conference in Paris produced an international agreement to try to limit global warming to 2 degrees C , and preferably 1.5 degrees C, above preindustrial levels.

Every country has its own approach to the challenge of addressing climate change. In the United States, which gets approximately 80 percent of its energy from fossil fuels, sophisticated efforts to downplay and critique the science led to major delays in climate action. For decades U.S. fossil fuel companies such as ExxonMobil worked to influence politicians to take as little action on emissions reductions as possible. Working with a small group of influential scientists, this well-funded, well-orchestrated campaign took many of its tactics from earlier tobacco-industry efforts to cast doubt on the links between smoking and cancer, as historians Naomi Oreskes and Erik Conway documented in their book Merchants of Doubt.

Perhaps the peak of U.S. climate denialism came in the late 1980s and into the 1990s — roughly a century after Swedish physical chemist Svante Arrhenius laid out the consequences of putting too much carbon dioxide into the atmosphere. In 1988 NASA scientist James Hansen testified to lawmakers about the consequences of global warming. “It is already happening now,” Hansen said, summarizing what scientists had long known.

The high-profile nature of Hansen’s testimony, combined with his NASA expertise, vaulted global warming into the public eye in the United States like never before. “It really hit home with a public who could understand that there are reasons that Venus is hot and Mars is cold,” says Joshua Howe, a historian at Reed College. “And that if you use that same reasoning, we have some concerns about what is happening here on Earth.” But Hansen also kicked off a series of bitter public battles about the reality of human-caused climate change that raged for years.        

One common approach of climate skeptics was to attack the environmental data and models that underlie climate science. In 1998, scientist Michael Mann, then at the University of Massachusetts–Amherst, and colleagues published a detailed temperature record that formed the basis of what came to be known as the “hockey stick” graph, so named because the chart showed a sharp rise in temperatures (the hockey blade) at the end of a long, much flatter period (the hockey stick). Skeptics soon demanded the data and software processing tools Mann used to create the graph. Bloggers and self-proclaimed citizen scientists created a cottage industry of questioning new climate science papers under the guise of “audits.” In 2009 hackers broke into a server at the University of East Anglia, a leading climate-research hub in Norwich, England, and released more than 1,000 e-mails between climate scientists. This “Climategate” scandal purported to reveal misconduct on the part of the researchers, but several reviews largely exonerated the scientists.  

The graph that launched climate skeptic attacks

This famous graph, produced by scientist Michael Mann and colleagues, and then reproduced in a 2001 report by the Intergovernmental Panel on Climate Change, dramatically captures temperature change over time. Climate change skeptics made it the center of an all-out attack on climate science.

Such tactics undoubtedly succeeded in feeding politicians’ delay on climate action in the United States, most of it from Republicans. President George W. Bush withdrew the country from the Kyoto Protocol in 2001 ; Donald Trump similarly rejected the Paris accord in 2017 . As late as 2015, the chair of the Senate’s environment committee, James Inhofe of Oklahoma, brought a snowball into Congress on a cold winter’s day in order to continue his argument that human-caused global warming is a “hoax.” In Australia, a similar mix of right-wing denialism and fossil fuel interests has kept climate change commitments in flux, as prime ministers are voted in and out over fierce debates about how the nation should act on climate.

Yet other nations have moved forward. Some European countries such as Germany aggressively pursued renewable energies, such as wind and solar, while activists such as the Swedish teenager Greta Thunberg — the vanguard of a youth-action movement — pressured their governments for more.

In recent years the developing economies of China and India have taken center stage in discussions about climate action. Both nations argue that they must be allowed extra time to wean themselves off fossil fuels in order to continue economic growth. They note that historically speaking, the United States is the largest total emitter of carbon by far.

Total carbon dioxide emissions by country, 1850–2021

These 20 nations have emitted the largest cumulative amounts of carbon dioxide since 1850. Emissions are shown in in billions of metric tons and are broken down into subtotals from fossil fuel use and cement manufacturing (blue) as well as from land use and forestry (green).

China, whose annual CO 2 emissions surpassed those of the United States in 2006, declared several moderate steps in 2021 to reduce emissions, including that it would stop building coal-burning power plants overseas. India announced it would aim for net-zero emissions by 2070, the first time it has set a date for this goal.

Yet such pledges continue to be criticized. At the 2021 U.N. Climate Change Conference in Glasgow, Scotland, India was globally criticized for not committing to a complete phaseout of coal — although the two top emitters, China and the United States, have not themselves committed to phasing out coal. “There is no equity in this,” says Aayushi Awasthy, an energy economist at the University of East Anglia. — Alexandra Witze

Facing a warmer future

Climate change creeps up gradually on society, except when it doesn’t. The slow increase in sea level, for instance, causes waters to lap incrementally higher at shorelines year after year. But when a big storm comes along — which may be happening more frequently due to climate change — the consequences become much more obvious. Storm surge rapidly swamps communities and wreaks disproportionate havoc. That’s why New York City installed floodgates in its subway and tunnel system in the wake of 2012’s Superstorm Sandy , and why the Pacific island nation of Tuvalu has asked Australia and New Zealand to be prepared to take in refugees fleeing from rising sea levels.

The list of climate impacts goes on and on — and in many cases, changes are coming faster than scientists had envisioned a few decades ago. The oceans are becoming more acidic as they absorb carbon dioxide, harming tiny marine organisms that build protective calcium carbonate shells and are the base of the marine food web. Warmer waters are bleaching coral reefs. Higher temperatures are driving animal and plant species into areas in which they previously did not live, increasing the risk of extinction for many. “It’s no longer about impacts in the future,” says Rachel Cleetus, a climate policy expert at the Union of Concerned Scientists. “It’s about what’s happening in the U.S. here and now, and around the world.”

No place on the planet is unaffected. In many areas, higher temperatures have led to major droughts, which dry out vegetation and provide additional fuel for wildfires such as those that have devastated Australia , the Mediterranean and western North America in recent years. The Colorado River , the source of water for tens of millions of people in the western United States , came under a water-shortage alert in 2021 for the first time in history.

Then there’s the Arctic, where temperatures are rising at more than twice the global average and communities are at the forefront of change. Permafrost is thawing, destabilizing buildings, pipelines and roads. Caribou and reindeer herders worry about the increased risk of parasites to the health of their animals. With less sea ice available to buffer the coast from storm erosion, the Inupiat village of Shishmaref, Alaska, risks crumbling into the sea. It will need to move from its sand-barrier island to the mainland .

“We know these changes are happening and that the Titanic is sinking,” says Louise Farquharson, a geomorphologist at the University of Alaska in Fairbanks who monitors permafrost and coastal change around Alaska. Like many Arctic scientists, she is working with Indigenous communities to understand the shifts they’re experiencing and what can be done when buildings start to slump and water supplies start to drain away. “A big part is just listening to community members and understanding what they’re seeing change,” she says.

All around the planet, those who depend on intact ecosystems for their survival face the greatest threat from climate change. And those with the least resources to adapt to climate change are the ones who feel it first .

“We are going to warm,” says Claudia Tebaldi, a climate scientist at Lawrence Berkeley National Laboratory in California. “There is no question about it. The only thing that we can hope to do is to warm a little more slowly.”

That’s one reason why the IPCC report released in 2021 focuses on anticipated levels of global warming. There is a big difference between the planet warming 1.5 degrees versus 2 degrees or 2.5 degrees. Consider that we are now at least 1.1 degrees above preindustrial levels of CO 2 and are already seeing dramatic shifts in climate. Given that, keeping further global temperature increases as low as possible will make a big difference in the climate impacts the planet faces. “With every fraction of a degree of warming, everything gets a little more intense,” says paleoclimatologist Jessica Tierney. “There’s no more time to beat around the bush.”

Historical and projected global temperature change

Various scenarios for how greenhouse gas emissions might change going forward help scientists predict future climate change. This graph shows the simulated historical temperature trend along with future projections of global surface temperature based on five scenarios from the Intergovernmental Panel on Climate Change. Temperature change is the difference from the 1850–1900 average.

The future rests on how much nations are willing to commit to cutting emissions and whether they will stick to those commitments. It’s a geopolitical balancing act the likes of which the world has never seen.

Science can and must play a role going forward. Improved climate models will illuminate what changes are expected at the regional scale, helping officials prepare. Governments and industry have crucial parts to play as well. They can invest in technologies, such as carbon sequestration, to help decarbonize the economy and shift society toward more renewable sources of energy. “We can solve these problems — most of the tools are already there,” says Cascade Tuholske, a geographer at Columbia University. “We just have to do it.”

Huge questions remain. Do voters have the will to demand significant energy transitions from their governments? How can business and military leaders play a bigger role in driving climate action? What should be the role of low-carbon energy sources that come with downsides, such as nuclear energy ? How can developing nations achieve a better standard of living for their people while not becoming big greenhouse gas emitters? How can we keep the most vulnerable from being disproportionately harmed during extreme events, and incorporate environmental and social justice into our future?

These questions become more pressing each year, as CO 2 accumulates in our atmosphere. The planet is now at higher levels of CO 2 than at any time in the last 3 million years. Yet Ralph Keeling, keeper of the iconic Mauna Loa record tracking the rise in atmospheric CO 2 , is already optimistically thinking about how scientists would be able to detect a slowdown, should the world actually start cutting emissions by a few percent per year. “That’s what the policy makers want to see — that there’s been some large-scale impact of what they did,” he says.

At the 2021 U.N. climate meeting in Glasgow diplomats from around the world agreed to work more urgently to shift away from using fossil fuels. They did not, however, adopt targets strict enough to keep the world below a warming of 1.5 degrees Celsius. It’s been well over a century since Svante Arrhenius recognized the consequences of putting extra carbon dioxide into the atmosphere, and yet world leaders have yet to pull together to avoid the most dangerous consequences of climate change.

Time is running out. — Alexandra Witze

Climate change facts

We know that climate change and its consequences are real, and we are responsible. Here’s what the science tells us.

How much has the planet warmed over the past century?

The planet’s average surface temperature has risen by at least 1.1 degree Celsius since preindustrial levels of 1850–1900.

What is causing climate change?

People are loading the atmosphere with carbon dioxide and other heat-trapping gases produced during the burning of fossil fuels, such as coal and gas, and cutting down forests.

What are some of the effects of climate change?

Ice sheets in Greenland and Antarctica are melting, raising sea levels and flooding low-lying island nations and coastal cities. Drought is parching farmlands and the rivers that feed them. Wildfires are raging. Rains are becoming more intense, and weather patterns are shifting.

What is the greenhouse effect?

In the 19th century, Irish physicist John Tyndall found that carbon dioxide gas, as well as water vapor, absorbed more heat than air alone. He argued that such gases would trap heat in Earth’s atmosphere, much as panes of glass trap heat in a greenhouse, and thus modulate climate.

What is the Keeling curve?

One of the most iconic datasets in all of science, the Keeling curve tracks the rise of atmospheric CO 2 . When geochemist Charles David Keeling began his measurements in 1958 on the Hawaiian volcano of Mauna Loa, CO 2 made up 315 parts per million of the global atmosphere. Each year the curve keeps going up: In 2016 it passed 400 ppm of CO 2 in the atmosphere, as measured during its typical annual minimum in September. In 2021, the annual minimum was 413 ppm.

Does it get hotter every year?

Average global temperatures fluctuate from year to year, but temperature observations taken at weather stations around the world confirm that we are living in the hottest years on record. The 10 warmest years since record keeping began in 1880 have all occurred since 2005. And nine of those 10 have come since 2010.

What countries emit the most carbon dioxide?

The United States has been the largest total emitter of carbon dioxide by far, followed by China and Russia. China’s annual CO 2 emissions surpassed those of the United States in 2006.

What places are impacted by climate change?

No place on the planet is unaffected. Higher temperatures have led to major droughts, providing fuel for wildfires such as those that have devastated Australia , the Mediterranean and western North America in recent years. The Colorado River came under a water-shortage alert in 2021 for the first time in history. In the Arctic, where temperatures are rising at more than twice the global average, permafrost is thawing, destabilizing buildings, pipelines and roads. With less sea ice available to buffer the coast from storm erosion, the Inupiat village of Shishmaref, Alaska, risks crumbling into the sea. All around the planet, those who depend on intact ecosystems for their survival face the greatest threat from climate change. And those with the least resources to adapt to climate change are the ones who feel it first .

Editor’s note: This story was published March 10, 2022.

British mathematician Lewis Fry Richardson (shown at center) proposes forecasting the weather by piecing together the calculations of tens of thousands of meteorologists working on small parts of the atmosphere.

Geochemist Charles David Keeling (shown in 1988) begins tracking the rise in atmospheric carbon dioxide at Mauna Loa in Hawaii. The record, which continues through today, has become one of the most iconic datasets in all of science.

Rachel Carson (shown) publishes the book Silent Spring , raising alarm over the ecological impacts of the pesticide DDT. The book helps catalyze the modern U.S. environmental movement.

The first Earth Day, organized by U.S. senator Gaylord Nelson and graduate student Denis Hayes, is celebrated.

The first Landsat satellite launched (shown), opening the door to continuous monitoring of Earth and its features from above.

A powerful eruption from the Philippines’ Mount Pinatubo (shown) ejects millions of tons of sulfur dioxide into the stratosphere, temporarily cooling the planet.  

World leaders gathered (shown) at the United Nations Conference on Environment and Development in Rio de Janeiro to address how to pursue economic development while also protecting the Earth. The meeting resulted in an international convention on climate change.

Activist Greta Thunberg initiates the “School Strike for Climate” movement by protesting outside the Swedish parliament. Soon, students around the world join a growing movement demanding action on climate change . (Activists at the 2021 U.N. Climate Change Conference are shown.)

From the archive

Climate change foreseen.

In an early mention of climate change in Science News-Letter , the predecessor of Science News , British meteorologist C.E.P. Brooks warns that present warming trends could lead to “important economic and political effects.”

IGY Brings Many Discoveries

Science News Letter lists the Top 8 accomplishments of the International Geophysical Year.

Chilling possibilities

Science News explores the tentative idea that global temperatures are cooling and that a new ice age could be imminent, which is later shown to be inaccurate.

Long Hot Future: Warmer Earth Appears Inevitable

“The planet earth will be a warmer place in the 21st century, and there is no realistic strategy that can prevent the change,” Science News reports.

Ozone and Global Warming: What to Do?

Policy makers discuss how to solve the dual problems of ozone depletion and global warming.

Looking for Mr. Greenhouse

Science writer Richard Monastersky reports on scientists’ efforts to evaluate how to connect increasing greenhouse gases and a warming climate.

World Climate Panel Charts Path for Action

The Intergovernmental Panel on Climate Change reports that “the fingerprint of man in the past temperature record” is now apparent.

Animals on the Move

A warming climate means shifting ranges and ecosystem disruptions for a lot of species, Nancy Ross-Flanigan reports.

Changing climate: 10 years after ‘An Inconvenient Truth’

A decade after former vice president Al Gore releases the documentary film An Inconvenient Truth , Science News looks back at how climate science has advanced.

With nowhere to hide from rising seas, Boston prepares for a wetter future

Mary Caperton Morton reports for Science News on how Boston is taking action to prepare for rising seas.

The new UN climate change report shows there’s no time for denial or delay

Earth & climate writer Carolyn Gramling covers the sixth assessment report from the Intergovernmental Panel on Climate Change, which documents how climate change is already affecting every region on Earth.

Climate change disinformation is evolving. So are efforts to fight back

Researchers are testing games and other ways to help people recognize climate change denial.

Extreme weather in 2022 showed the global impact of climate change

Heat waves, floods, wildfires and drought around the world were exacerbated by Earth’s changing climate.

It’s possible to reach net-zero carbon emissions. Here’s how

Cutting carbon dioxide emissions to curb climate change and reach net zero is possible but not easy.

The last 12 months were the hottest on record

The planet’s average temperature was about 1.3 degrees Celsius higher than the 1850–1900 average, a new report finds.

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What Are the Causes of Climate Change?

We can’t fight climate change without understanding what drives it.

Low water levels at Shasta Lake, California, following a historic drought in October 2021

Andrew Innerarity/California Department of Water Resources

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At the root of climate change is the phenomenon known as the greenhouse effect , the term scientists use to describe the way that certain atmospheric gases “trap” heat that would otherwise radiate upward, from the planet’s surface, into outer space. On the one hand, we have the greenhouse effect to thank for the presence of life on earth; without it, our planet would be cold and unlivable.

But beginning in the mid- to late-19th century, human activity began pushing the greenhouse effect to new levels. The result? A planet that’s warmer right now than at any other point in human history, and getting ever warmer. This global warming has, in turn, dramatically altered natural cycles and weather patterns, with impacts that include extreme heat, protracted drought, increased flooding, more intense storms, and rising sea levels. Taken together, these miserable and sometimes deadly effects are what have come to be known as climate change .

Detailing and discussing the human causes of climate change isn’t about shaming people, or trying to make them feel guilty for their choices. It’s about defining the problem so that we can arrive at effective solutions. And we must honestly address its origins—even though it can sometimes be difficult, or even uncomfortable, to do so. Human civilization has made extraordinary productivity leaps, some of which have led to our currently overheated planet. But by harnessing that same ability to innovate and attaching it to a renewed sense of shared responsibility, we can find ways to cool the planet down, fight climate change , and chart a course toward a more just, equitable, and sustainable future.

Here’s a rough breakdown of the factors that are driving climate change.

Natural causes of climate change

Human-driven causes of climate change, transportation, electricity generation, industry & manufacturing, agriculture, oil & gas development, deforestation, our lifestyle choices.

Some amount of climate change can be attributed to natural phenomena. Over the course of Earth’s existence, volcanic eruptions , fluctuations in solar radiation , tectonic shifts , and even small changes in our orbit have all had observable effects on planetary warming and cooling patterns.

But climate records are able to show that today’s global warming—particularly what has occured since the start of the industrial revolution—is happening much, much faster than ever before. According to NASA , “[t]hese natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades.” And the records refute the misinformation that natural causes are the main culprits behind climate change, as some in the fossil fuel industry and conservative think tanks would like us to believe.

Chemical manufacturing plants emit fumes along Onondaga Lake in Solvay, New York, in the late-19th century. Over time, industrial development severely polluted the local area.

Library of Congress, Prints & Photographs Division, Detroit Publishing Company Collection

Scientists agree that human activity is the primary driver of what we’re seeing now worldwide. (This type of climate change is sometimes referred to as anthropogenic , which is just a way of saying “caused by human beings.”) The unchecked burning of fossil fuels over the past 150 years has drastically increased the presence of atmospheric greenhouse gases, most notably carbon dioxide . At the same time, logging and development have led to the widespread destruction of forests, wetlands, and other carbon sinks —natural resources that store carbon dioxide and prevent it from being released into the atmosphere.

Right now, atmospheric concentrations of greenhouse gases like carbon dioxide, methane , and nitrous oxide are the highest they’ve been in the last 800,000 years . Some greenhouse gases, like hydrochlorofluorocarbons (HFCs) , do not even exist in nature. By continuously pumping these gases into the air, we helped raise the earth’s average temperature by about 1.9 degrees Fahrenheit during the 20th century—which has brought us to our current era of deadly, and increasingly routine, weather extremes. And it’s important to note that while climate change affects everyone in some way, it doesn’t do so equally: All over the world, people of color and those living in economically disadvantaged or politically marginalized communities bear a much larger burden , despite the fact that these communities play a much smaller role in warming the planet.

Our ways of generating power for electricity, heat, and transportation, our built environment and industries, our ways of interacting with the land, and our consumption habits together serve as the primary drivers of climate change. While the percentages of greenhouse gases stemming from each source may fluctuate, the sources themselves remain relatively consistent.

Traffic on Interstate 25 in Denver

David Parsons/iStock

The cars, trucks, ships, and planes that we use to transport ourselves and our goods are a major source of global greenhouse gas emissions. (In the United States, they actually constitute the single-largest source.) Burning petroleum-based fuel in combustion engines releases massive amounts of carbon dioxide into the atmosphere. Passenger cars account for 41 percent of those emissions, with the typical passenger vehicle emitting about 4.6 metric tons of carbon dioxide per year. And trucks are by far the worst polluters on the road. They run almost constantly and largely burn diesel fuel, which is why, despite accounting for just 4 percent of U.S. vehicles, trucks emit 23 percent of all greenhouse gas emissions from transportation.

We can get these numbers down, but we need large-scale investments to get more zero-emission vehicles on the road and increase access to reliable public transit .

As of 2021, nearly 60 percent of the electricity used in the United States comes from the burning of coal, natural gas , and other fossil fuels . Because of the electricity sector’s historical investment in these dirty energy sources, it accounts for roughly a quarter of U.S. greenhouse gas emissions, including carbon dioxide, methane, and nitrous oxide.

That history is undergoing a major change, however: As renewable energy sources like wind and solar become cheaper and easier to develop, utilities are turning to them more frequently. The percentage of clean, renewable energy is growing every year—and with that growth comes a corresponding decrease in pollutants.

But while things are moving in the right direction, they’re not moving fast enough. If we’re to keep the earth’s average temperature from rising more than 1.5 degrees Celsius, which scientists say we must do in order to avoid the very worst impacts of climate change, we have to take every available opportunity to speed up the shift from fossil fuels to renewables in the electricity sector.

The factories and facilities that produce our goods are significant sources of greenhouse gases; in 2020, they were responsible for fully 24 percent of U.S. emissions. Most industrial emissions come from the production of a small set of carbon-intensive products, including basic chemicals, iron and steel, cement and concrete, aluminum, glass, and paper. To manufacture the building blocks of our infrastructure and the vast array of products demanded by consumers, producers must burn through massive amounts of energy. In addition, older facilities in need of efficiency upgrades frequently leak these gases, along with other harmful forms of air pollution .

One way to reduce the industrial sector’s carbon footprint is to increase efficiency through improved technology and stronger enforcement of pollution regulations. Another way is to rethink our attitudes toward consumption (particularly when it comes to plastics ), recycling , and reuse —so that we don’t need to be producing so many things in the first place. And, since major infrastructure projects rely heavily on industries like cement manufacturing (responsible for 7 percent of annual global greenhouse gas), policy mandates must leverage the government’s purchasing power to grow markets for cleaner alternatives, and ensure that state and federal agencies procure more sustainably produced materials for these projects. Hastening the switch from fossil fuels to renewables will also go a long way toward cleaning up this energy-intensive sector.

The advent of modern, industrialized agriculture has significantly altered the vital but delicate relationship between soil and the climate—so much so that agriculture accounted for 11 percent of U.S. greenhouse gas emissions in 2020. This sector is especially notorious for giving off large amounts of nitrous oxide and methane, powerful gases that are highly effective at trapping heat. The widespread adoption of chemical fertilizers , combined with certain crop-management practices that prioritize high yields over soil health, means that agriculture accounts for nearly three-quarters of the nitrous oxide found in our atmosphere. Meanwhile, large-scale industrialized livestock production continues to be a significant source of atmospheric methane, which is emitted as a function of the digestive processes of cattle and other ruminants.

Stephen McComber holds a squash harvested from the community garden in Kahnawà:ke Mohawk Territory, a First Nations reserve of the Mohawks of Kahnawà:ke, in Quebec.

Stephanie Foden for NRDC

But farmers and ranchers—especially Indigenous farmers, who have been tending the land according to sustainable principles —are reminding us that there’s more than one way to feed the world. By adopting the philosophies and methods associated with regenerative agriculture , we can slash emissions from this sector while boosting our soil’s capacity for sequestering carbon from the atmosphere, and producing healthier foods.

A decades-old, plugged and abandoned oil well at a cattle ranch in Crane County, Texas, in June 2021, when it was found to be leaking brine water

Matthew Busch/Bloomberg via Getty Images

Oil and gas lead to emissions at every stage of their production and consumption—not only when they’re burned as fuel, but just as soon as we drill a hole in the ground to begin extracting them. Fossil fuel development is a major source of methane, which invariably leaks from oil and gas operations : drilling, fracking , transporting, and refining. And while methane isn’t as prevalent a greenhouse gas as carbon dioxide, it’s many times more potent at trapping heat during the first 20 years of its release into the atmosphere. Even abandoned and inoperative wells—sometimes known as “orphaned” wells —leak methane. More than 3 million of these old, defunct wells are spread across the country and were responsible for emitting more than 280,000 metric tons of methane in 2018.

Unsurprisingly, given how much time we spend inside of them, our buildings—both residential and commercial—emit a lot of greenhouse gases. Heating, cooling, cooking, running appliances, and maintaining other building-wide systems accounted for 13 percent of U.S. emissions overall in 2020. And even worse, some 30 percent of the energy used in U.S. buildings goes to waste, on average.

Every day, great strides are being made in energy efficiency , allowing us to achieve the same (or even better) results with less energy expended. By requiring all new buildings to employ the highest efficiency standards—and by retrofitting existing buildings with the most up-to-date technologies—we’ll reduce emissions in this sector while simultaneously making it easier and cheaper for people in all communities to heat, cool, and power their homes: a top goal of the environmental justice movement.

An aerial view of clearcut sections of boreal forest near Dryden in Northwestern Ontario, Canada, in June 2019

River Jordan for NRDC

Another way we’re injecting more greenhouse gas into the atmosphere is through the clearcutting of the world’s forests and the degradation of its wetlands . Vegetation and soil store carbon by keeping it at ground level or underground. Through logging and other forms of development, we’re cutting down or digging up vegetative biomass and releasing all of its stored carbon into the air. In Canada’s boreal forest alone, clearcutting is responsible for releasing more than 25 million metric tons of carbon dioxide into the atmosphere each year—the emissions equivalent of 5.5 million vehicles.

Government policies that emphasize sustainable practices, combined with shifts in consumer behavior , are needed to offset this dynamic and restore the planet’s carbon sinks .

The Yellow Line Metro train crossing over the Potomac River from Washington, DC, to Virginia on June 24, 2022

Sarah Baker

The decisions we make every day as individuals—which products we purchase, how much electricity we consume, how we get around, what we eat (and what we don’t—food waste makes up 4 percent of total U.S. greenhouse gas emissions)—add up to our single, unique carbon footprints . Put all of them together and you end up with humanity’s collective carbon footprint. The first step in reducing it is for us to acknowledge the uneven distribution of climate change’s causes and effects, and for those who bear the greatest responsibility for global greenhouse gas emissions to slash them without bringing further harm to those who are least responsible .

The big, climate-affecting decisions made by utilities, industries, and governments are shaped, in the end, by us : our needs, our demands, our priorities. Winning the fight against climate change will require us to rethink those needs, ramp up those demands , and reset those priorities. Short-term thinking of the sort that enriches corporations must give way to long-term planning that strengthens communities and secures the health and safety of all people. And our definition of climate advocacy must go beyond slogans and move, swiftly, into the realm of collective action—fueled by righteous anger, perhaps, but guided by faith in science and in our ability to change the world for the better.

If our activity has brought us to this dangerous point in human history, breaking old patterns can help us find a way out.

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Words at Ease

6 Example Speeches on Climate Change

Climate change is one of the most pressing issues of our time, affecting every corner of the globe and every aspect of our lives.

As a speaker, addressing this topic can be challenging, but it’s also an opportunity to inspire action and create meaningful change.

Example Speeches on Climate Change

In this article, we’ll explore six example speeches on climate change, each tailored to different audiences and occasions.

Whether you’re looking for a short, impactful speech or a longer, more in-depth exploration of the issue, you’ll find inspiration and guidance here.

So, let’s get started and see how we can use the power of words to tackle one of the greatest challenges of our generation.

Speech 1: A Call to Action (Short – 300 words)

Friends, we gather here today because our planet is in crisis. The science is clear: climate change is real, it’s happening now, and it’s caused by human activity. We’ve seen the devastating effects all around us – from rising sea levels and more frequent natural disasters to droughts, famines, and the loss of biodiversity. But we also know that it’s not too late to act. We have the power to change course, to build a more sustainable future for ourselves and for generations to come.

So, what can we do? First, we must recognize that every action counts. From the choices we make as individuals – like reducing our energy consumption and waste – to the policies we support as citizens, we all have a role to play. Second, we must hold our leaders accountable. We need bold, decisive action at every level of government to transition to clean energy, protect vulnerable communities, and build resilience against the impacts of climate change.

But most importantly, we must act together. Climate change is a global problem that requires global solutions. We must stand united, across borders and differences, in our commitment to this fight. Because when we work together, there’s nothing we can’t achieve.

So let us leave here today with a renewed sense of purpose. Let us go out into the world and be the change we wish to see. Let us build a future where our planet thrives, where our communities are resilient, and where every person has the chance to live with dignity and hope. The time for action is now – let’s get to work.

— END OF SPEECH —

Commentary: This short speech is a powerful call to action on climate change. It acknowledges the severity of the problem, highlights the importance of individual and collective action, and ends with an inspiring vision for the future. This speech would be suitable for a rally, a community event, or any occasion where you want to motivate people to get involved in the fight against climate change.

Speech 2: The Business Case for Climate Action (Medium-length – 500 words)

As business leaders, we have a unique opportunity – and a profound responsibility – to drive the transition to a low-carbon economy. For too long, we’ve treated climate change as a distant threat, something to be dealt with in the future. But the reality is that the impacts of climate change are already being felt, and they pose significant risks to our businesses, our communities, and our planet.

The good news is that tackling climate change isn’t just the right thing to do – it’s also good for business. By investing in clean energy, sustainable supply chains, and climate-resilient infrastructure, we can not only reduce our environmental impact but also create new opportunities for growth and innovation.

Consider the facts: renewable energy is now cheaper than fossil fuels in many parts of the world, and the cost continues to fall. Companies that embrace sustainability are seeing increased customer loyalty, employee satisfaction, and investor confidence. And as governments around the world implement policies to drive the transition to a low-carbon economy, businesses that are ahead of the curve will be well-positioned to thrive.

But we can’t do it alone. We need policymakers to create the right incentives and frameworks to support our efforts. We need consumers to demand sustainable products and services. And we need every business, large and small, to join us in this critical mission.

So, let us seize this moment. Let us lead by example, showing the world that sustainability and profitability can go hand in hand. Let us work together to build a future where businesses prosper, communities thrive, and our planet is protected for generations to come. The path ahead won’t be easy, but with courage, collaboration, and a commitment to doing what’s right, we can rise to the challenge and create a better world for all.

Commentary: This speech makes a compelling business case for climate action. It acknowledges the risks that climate change poses to businesses, highlights the opportunities that come with the transition to a low-carbon economy and calls on business leaders to lead by example. This speech would be suitable for a business conference, a sustainability event, or any occasion where you want to encourage businesses to take action on climate change.

Speech 3: The Moral Imperative of Climate Action (Long – 700 words)

My fellow citizens, we stand at a crossroads in human history. The choices we make in the coming years will determine the fate of our planet and the future of generations to come. And there is no greater moral imperative of our time than to act on climate change.

For too long, we have treated our planet as if it were an endless resource, a dumping ground for our waste and pollution. We have prioritized short-term gains over long-term sustainability, and we have turned a blind eye to the consequences of our actions. But now, those consequences are catching up with us.

We see it in the rising seas that threaten our coastal cities, the wildfires that ravage our forests, and the droughts that decimate our crops. We see it in the mass extinction of species, the acidification of our oceans, the spread of disease, and conflict. Climate change is not just an environmental issue – it is a humanitarian crisis of unprecedented proportions.

And yet, even in the face of this overwhelming evidence, there are still those who deny the reality of climate change, who prioritize profit over people, who cling to the status quo rather than embracing the need for change. But we cannot afford to be complacent or complicit any longer.

As a global community, we have a moral obligation to act. We must protect the most vulnerable among us, to safeguard the planet for future generations, to ensure that every person has the right to a livable future. This is not a partisan issue – it is a human issue, and it demands a human response.

So, what can we do? We must start by recognizing that climate change is a systemic problem that requires systemic solutions. We need to transform the way we produce and consume energy, the way we grow and distribute food, and the way we move and build and live. We need to invest in clean technologies, sustainable infrastructure, in resilient communities. And we need to do it now, with the urgency and the scale that this crisis demands.

But we cannot do it alone. We need every nation, every sector, and every individual to be part of the solution. We need to build a global movement for change, one that transcends borders and ideologies, one that unites us in our common humanity and our shared destiny.

So let us rise to this challenge. Let us summon the courage and the compassion to act, not just for ourselves, but for all those who will come after us. Let us be the generation that saves our planet, that secures a livable future for all. The time for action is now – let us meet this moment with the urgency and the moral clarity it demands. Thank you.

Commentary: This speech frames climate action as a moral imperative, highlighting the devastating impacts of climate change and the urgent need for systemic solutions. It calls on individuals, nations, and sectors to unite in a global movement for change and emphasizes the importance of acting with compassion and urgency. This speech would be suitable for a keynote address, a commencement speech, or any occasion where you want to inspire people to take bold, principled action on climate change.

Speech 4: The Role of Youth in Combating Climate Change (Long – 800 words)

Young people of the world, you are the inheritors of a planet in peril. You are the ones who will bear the brunt of the climate crisis, and you are the ones who have the most to lose if we fail to act. But you are also the ones who have the most to gain if we succeed – and you are the ones who have the power to lead us to a better future.

For too long, the voices of youth have been marginalized in the climate debate. You have been told that you are too young to understand, too naive to make a difference, and too powerless to effect change. But I stand here today to tell you that nothing could be further from the truth.

You are not just the future – you are the present. You are the ones who are taking to the streets, organizing strikes and protests, demanding action from those in power. You are the ones who are innovating new solutions, creating new businesses, and driving new technologies. You are the ones who are shaping the culture, influencing the conversation, setting the agenda for change.

And you are not alone. Around the world, young people are rising and speaking out, united in their determination to create a better, more sustainable future. From the school strikers of Europe to the Indigenous activists of the Amazon, from the green entrepreneurs of Africa to the climate justice advocates of Asia, you are part of a global movement that is growing stronger every day.

But the road ahead will not be easy. You will face resistance from those who benefit from the status quo, from those who are invested in the fossil fuel economy, and from those who are afraid of change. You will face setbacks and challenges, moments of doubt and despair.

But you must not lose heart. You must remember that you have the truth on your side, the science on your side, and the moral imperative on your side. You must remember that you are not fighting for yourselves alone, but for all those who will come after you, for the generations yet unborn.

So let us stand together, young and old, rich and poor, from every corner of the globe. Let us build a movement that is inclusive, intersectional, and unstoppable. Let us demand action from our leaders, hold them accountable for their promises, and work to elect those who share our vision for a just and sustainable future.

And let us never forget that the power to change the world lies within each of us. Every action we take, every choice we make, every voice we raise – no matter how small – can make a difference. So let us go forth from this place with courage, with conviction, with hope. Let us be the change we wish to see in the world. Let us create a future that we can be proud of, a future that we can pass on to those who come after us. The time is now – let us seize it together.

Commentary: This speech is a powerful call to action for young people, emphasizing their crucial role in the fight against climate change. It acknowledges the challenges they face but also highlights their unique strengths and the importance of building an inclusive, intersectional movement. The speech ends with an inspiring message of hope and empowerment, urging young people to seize the moment and create a better future for all. This speech would be ideal for a youth climate conference, a university event, or any occasion where you want to mobilize and inspire young people to take action on climate change.

Speech 5: The Intersection of Climate Change and Social Justice (Lengthy – 1,000 words)

Friends, we have gathered here today to discuss one of the most pressing issues of our time – the intersection of climate change and social justice. For too long, these two issues have been treated as separate and distinct, as if the impacts of a warming planet could be neatly compartmentalized from the struggles for equality, dignity, and human rights. But the truth is that climate change is not just an environmental crisis – it is a human rights crisis, and it is a crisis that disproportionately affects the most vulnerable and marginalized among us.

Consider the facts: the communities that are most impacted by climate change – low-income communities, communities of color, and indigenous communities – are also the communities that have contributed the least to the problem. They are the ones who bear the brunt of the rising seas and the extreme weather events, the ones who suffer the most from the health impacts of air and water pollution, and the ones who are most likely to be displaced by drought, famine, and conflict.

And yet, these are also the communities that have been systematically excluded from the decision-making processes that shape our response to the climate crisis. Their voices have been silenced, their needs have been ignored, and their rights have been denied. This is not just an injustice – it is a fundamental failure of our democracy and our humanity.

But we cannot address climate change without addressing these underlying inequities. We cannot build a sustainable future on a foundation of inequality and exploitation. We cannot solve a global problem with solutions that leave entire populations behind.

So, what do we do? We start by recognizing that climate justice and social justice are inextricably linked. We cannot have one without the other. We need to approach the climate crisis with an intersectional lens, understanding how it intersects with issues of race, class, gender, and power.

We need to center the voices and experiences of those who are most impacted by climate change and ensure that they have a seat at the table when decisions are being made. We need to invest in community-led solutions, resilience, and adaptation strategies that are grounded in local knowledge and experience.

We need to hold corporations and governments accountable for their role in perpetuating the climate crisis and the inequities that it exacerbates. We need to demand a just transition to a clean energy economy, one that creates good jobs and opportunities for all, not just a privileged few.

And we need to build a movement that is truly inclusive and intersectional, one that recognizes the interconnectedness of all our struggles and all our hopes. We need to stand in solidarity with those who are fighting for justice on all fronts – from the streets of Ferguson to the forests of the Amazon, from the mines of Appalachia to the island nations of the Pacific.

This is not an easy task. It will require us to confront uncomfortable truths, challenge entrenched systems of power, to build new alliances and coalitions. But it is a task that we must undertake, for the sake of our planet and our people.

Because in the end, we are all in this together. We all share one planet, one home, one future. And we all have a role to play in shaping that future – not just for ourselves, but for generations to come.

So let us leave here today with a renewed commitment to justice, equity, to solidarity. Let us work to build a world where every person has the right to a livable planet, a world where the benefits and burdens of climate action are shared fairly and equitably, and a world where we recognize our common humanity and our common fate.

The road ahead will not be easy, but we have the power to choose the path we take. Let us choose the path of justice, the path of compassion, the path of a sustainable and equitable future for all. Thank you.

Commentary: This speech powerfully articulates the intersection of climate change and social justice, highlighting how the impacts of climate change disproportionately affect marginalized communities. It calls for an intersectional approach to climate action, one that centers the voices and experiences of those most impacted and invests in community-led solutions. The speech emphasizes the need for accountability, a just transition, and an inclusive, intersectional movement. It ends with a stirring call to action, urging the audience to commit to justice, equity, and solidarity in the fight for a sustainable future. This speech would be suitable for a social justice conference, an environmental justice event, or any occasion where you want to highlight the systemic inequities of the climate crisis and inspire people to take intersectional action.

Speech 6: Climate Change and the Future of Humanity (Lengthy – 1,000 words or more)

My fellow humans, we stand at a pivotal moment in the history of our species. The choices we make in the coming years will determine not just the fate of our planet, but the fate of humanity itself. And there is no greater threat to our future than the reality of climate change.

For decades, we have known that our addiction to fossil fuels, our relentless consumption and waste, and our disregard for the natural world – all these things have been pushing our planet to the brink. We have seen the evidence in the melting of the polar ice caps, the bleaching of the coral reefs, and the extinction of countless species. We have felt the impacts of the rising temperatures and the extreme weather events, the droughts and the floods, and the wildfires that have become the new normal.

And yet, even in the face of this overwhelming evidence, we have been slow to act. We have been held back by the forces of inertia and denial, by the vested interests of those who profit from the status quo, and by the short-sightedness of those who prioritize present gains over future sustainability.

But we cannot afford to wait any longer. The science is clear: if we do not take urgent and dramatic action to reduce our greenhouse gas emissions, transition to a clean energy economy, to transform the way we live work, and consume – then we risk crossing irreversible tipping points that will lead to catastrophic and irreversible climate change.

This is not just an environmental issue – it is an existential threat to human civilization as we know it. It is a threat to our food and water security, to our public health and safety, to our economic stability and geopolitical security. It is a threat to the very foundations of our society and our way of life.

But it is also an opportunity – an opportunity to reimagine our relationship with the natural world, to build a more just and equitable society, and to create a future that is not just sustainable, but regenerative and thriving.

We have the tools and the knowledge to make this transition. We have renewable energy technologies, sustainable agriculture practices, the green infrastructure solutions. We have the economic models and policy frameworks, the social movements, and cultural shifts.

What we need now is the political will and the moral courage to act. We need leaders who are willing to stand up to the fossil fuel industry, to the corporate polluters, to the forces of greed and exploitation. We need citizens who are willing to demand change, to hold their governments accountable, and to make the necessary sacrifices and investments.

And we need to do it together – as a global community, as a human family. Because climate change knows no borders, no boundaries, no divisions of race or class or creed. It affects us all, and it will take all of us to solve it.

So let us rise to this challenge, let us seize this moment. Let us look to the examples of those who have gone before us – the Indigenous peoples who have stewarded this land for generations, the environmental activists who have fought tirelessly for change, and the scientists and innovators who have given us the tools to build a better world.

Let us draw strength from their courage and their wisdom, and let us add our voices and actions to the growing chorus for change. Let us build an unstoppable movement, a movement that is rooted in love, justice, and compassion for all living things.

And let us never forget what is at stake – the future of our children and grandchildren, the future of all the species with whom we share this planet, and the future of life itself. We are the guardians of this precious and fragile world, and it is our sacred duty to protect it.

So let us go forth from this place with a renewed sense of purpose and urgency. Let us work to create a world where clean air, water, and soil are not luxuries but fundamental rights, where renewable energy powers our homes and our economies, and where nature is valued, protected, and restored.

Let us create a world where every person has the opportunity to thrive, where poverty and inequality are relics of the past, and where justice and compassion are the guiding principles of our society. Let us create a world that is worthy of the sacrifices and the struggles of those who came before us, and that is a testament to the boundless potential of the human spirit.

This is our moment, our opportunity, our responsibility. Let us rise to meet it with everything we have, with all the love, courage, and determination in our hearts. For the sake of our planet, for the sake of our children, for the sake of our very survival – let us act, and let us act now. Thank you.

Commentary: This speech is a powerful and impassioned call to action on climate change, framing it as an existential threat to human civilization and a moral imperative for urgent and dramatic action. It highlights the devastating impacts of climate change, the forces of inertia and denial that have held us back, and the opportunities for a just and sustainable transition. The speech calls for political will, moral courage, and global solidarity in the face of this crisis and ends with a stirring vision of a world transformed by a movement rooted in love, justice, and compassion. This speech would be ideal for a major international conference, a UN summit, or any high-profile event where you want to galvanize global action on climate change and inspire people with a transformative vision of the future.

Climate change is a complex and intimidating challenge, but it is also an opportunity to build a better world.

By crafting powerful and persuasive speeches, we can inspire others to action, mobilize communities and movements, and create the political will for change.

Whether you’re speaking to a small group or a global audience, remember to frame the issue in terms that resonate with your listeners, highlight both the urgency of the crisis and the opportunities for solutions, and call people to action with a vision of a just and sustainable future.

Together, we can rise to meet this moment and create a world that is worthy of the generations to come.

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• 06 September 2024

How to change people’s minds about climate change: what the science says

• Alix Soliman

You can also search for this author in PubMed   Google Scholar

How you deliver climate messaging matters, in terms of changing minds, researchers are finding. Credit: Jewel Samad/AFP via Getty

Telling people that scientists almost unanimously agree that human-caused climate change is happening can help to nudge their thinking in that direction. A study published last month in Nature Human Behaviour 1 , tested this ‘consensus message’ across 27 countries and found that the people least familiar with the message or who were sceptical of climate science were the most likely to change their perspective when presented with it.

Climate-communication researchers who spoke to Nature ’s news team say that the findings add to a growing body of social science identifying the best strategies to help people come to grips with the concept that climate change is real — but that consensus messaging doesn’t always translate to a lasting shift in perspective.

For an enduring shift, they suggest, the message needs to be personally relevant. That’s because “ climate change is affecting the people and places and things that we love right now”, says Anthony Leiserowitz, the director of the Yale Program on Climate Change Communication in New Haven, Connecticut.

Communicating consensus

Many studies have found that informing people of the scientific consensus on climate change can shift their attitude 2 , 3 . But most have focused on climate opinions in the United States. Bojana Većkalov, a social psychologist at the University of Amsterdam, and her colleagues wanted to see whether that messaging works cross-culturally.

False statements about climate change trip people up

They shared an online survey through social media and e-mail newsletters, and then analysed 10,527 responses from people across 27 countries. Respondents estimated the proportion of climate scientists who they think agree that human-caused climate change exists. They then ranked how confident they were in their estimates and shared their own opinions. Afterwards, the researchers showed the participants several facts, including that 97% of climate scientists agree that human-caused climate change is real 4 , and then re-polled them.

The fact that some — including those who are politically conservative — shifted their views is a “testament to the universal cultural authority of science”, Većkalov says.

David Holmes, a media sociologist and the chief executive of the non-profit organization Climate Communications Australia in Melbourne, says that this study “reconfirmed previous studies” showing that consensus messaging works, even on a global scale. He wishes, however, that the team could have teased out country-level trends or discerned whether various cultural attitudes had an impact on the results. The study also didn’t test whether the change was lasting.

Personal relevance

What’s clear from this study and others, however, is that climate-communication strategies have become more sophisticated as researchers have learnt what works. Gone are the days of showing a polar bear clinging to a melting ice sheet to explain the seriousness of the situation. It’s important to talk about global warming, “not as a polar bear issue, but as a people issue”, Leiserowitz says.

The rise of eco-anxiety: scientists wake up to the mental-health toll of climate change

An emerging area of research that shows promise, researchers say, is how personal conversations help. Start with things your audience cares about, such as food prices, national security or fishing, says Matthew Goldberg, a climate-communication researcher at Yale University. “There is a climate-change angle to almost everything,” he adds.

Montana Burgess is the executive director at Neighbours United, a non-profit advocacy organization in Castlegar, Canada. The organization created a climate-conversation toolkit after having success running a campaign persuading people in a rural town in Canada to support a renewable-energy policy. Burgess says that one top strategy is to “get out of talking-point fact land” by exchanging personal stories. For instance, because wildfires have worsened in Canada, there are now “six weeks of the year where it’s too smoky and hot to let my kid go outside, and my kid has asthma”, Burgess says. She remembers only a handful of smoky days when she was growing up, so she shares that experience to help people process the changes they are seeing.

The next step is to listen carefully and “connect the dots” between a person’s experience and local climate information, Goldberg says.

This strategy is based on a landmark study 5 in which canvassers went door-to-door and had ten-minute conversations with voters in Miami, Florida, that were geared towards reducing prejudice towards transgender people. After sharing their views, voters were asked to talk about a time they faced judgment for being different than others. The conversations increased support for a non-discrimination law, and social acceptance persisted when participants were re-surveyed three months later. Using this strategy with climate change specifically is still being systematically tested.

Leiserowitz has a personal experience that suggests the strategy will work. He has a family member who used to deny climate change. “It has taken me about 20 years of slow, careful, loving, supportive conversations” to change their mind, he says.

doi: https://doi.org/10.1038/d41586-024-02777-9

Većkalov, B. et al. Nature Hum. Behav . https://doi.org/10.1038/s41562-024-01928-2 (2024).

Article   PubMed   Google Scholar  

Lewandowsky, S., Gignac, G. E. & Vaughan, S. Nature Clim. Change. 3 , 399–404 (2013).

Article   Google Scholar  

Van der Linden, S., Leiserowitz, A. & Maibach, E. J. Environ. Psychol. 62 , 49–58 (2019).

Cook, J. et al. Environ. Res. Lett. 8 , 024024 (2013).

Broockman, D. & Kalla, J. Science 352 , 220–224 (2016).

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Climate Change: Evidence and Causes: Update 2020 (2020)

Chapter: conclusion, c onclusion.

This document explains that there are well-understood physical mechanisms by which changes in the amounts of greenhouse gases cause climate changes. It discusses the evidence that the concentrations of these gases in the atmosphere have increased and are still increasing rapidly, that climate change is occurring, and that most of the recent change is almost certainly due to emissions of greenhouse gases caused by human activities. Further climate change is inevitable; if emissions of greenhouse gases continue unabated, future changes will substantially exceed those that have occurred so far. There remains a range of estimates of the magnitude and regional expression of future change, but increases in the extremes of climate that can adversely affect natural ecosystems and human activities and infrastructure are expected.

Citizens and governments can choose among several options (or a mixture of those options) in response to this information: they can change their pattern of energy production and usage in order to limit emissions of greenhouse gases and hence the magnitude of climate changes; they can wait for changes to occur and accept the losses, damage, and suffering that arise; they can adapt to actual and expected changes as much as possible; or they can seek as yet unproven “geoengineering” solutions to counteract some of the climate changes that would otherwise occur. Each of these options has risks, attractions and costs, and what is actually done may be a mixture of these different options. Different nations and communities will vary in their vulnerability and their capacity to adapt. There is an important debate to be had about choices among these options, to decide what is best for each group or nation, and most importantly for the global population as a whole. The options have to be discussed at a global scale because in many cases those communities that are most vulnerable control few of the emissions, either past or future. Our description of the science of climate change, with both its facts and its uncertainties, is offered as a basis to inform that policy debate.

A CKNOWLEDGEMENTS

The following individuals served as the primary writing team for the 2014 and 2020 editions of this document:

• Eric Wolff FRS, (UK lead), University of Cambridge
• Inez Fung (NAS, US lead), University of California, Berkeley
• Brian Hoskins FRS, Grantham Institute for Climate Change
• John F.B. Mitchell FRS, UK Met Office
• Tim Palmer FRS, University of Oxford
• Benjamin Santer (NAS), Lawrence Livermore National Laboratory
• John Shepherd FRS, University of Southampton
• Keith Shine FRS, University of Reading.
• Susan Solomon (NAS), Massachusetts Institute of Technology
• Kevin Trenberth, National Center for Atmospheric Research
• John Walsh, University of Alaska, Fairbanks
• Don Wuebbles, University of Illinois

Staff support for the 2020 revision was provided by Richard Walker, Amanda Purcell, Nancy Huddleston, and Michael Hudson. We offer special thanks to Rebecca Lindsey and NOAA Climate.gov for providing data and figure updates.

The following individuals served as reviewers of the 2014 document in accordance with procedures approved by the Royal Society and the National Academy of Sciences:

• Richard Alley (NAS), Department of Geosciences, Pennsylvania State University
• Alec Broers FRS, Former President of the Royal Academy of Engineering
• Harry Elderfield FRS, Department of Earth Sciences, University of Cambridge
• Joanna Haigh FRS, Professor of Atmospheric Physics, Imperial College London
• Isaac Held (NAS), NOAA Geophysical Fluid Dynamics Laboratory
• John Kutzbach (NAS), Center for Climatic Research, University of Wisconsin
• Jerry Meehl, Senior Scientist, National Center for Atmospheric Research
• John Pendry FRS, Imperial College London
• John Pyle FRS, Department of Chemistry, University of Cambridge
• Gavin Schmidt, NASA Goddard Space Flight Center
• Emily Shuckburgh, British Antarctic Survey
• Gabrielle Walker, Journalist
• Andrew Watson FRS, University of East Anglia

The Support for the 2014 Edition was provided by NAS Endowment Funds. We offer sincere thanks to the Ralph J. and Carol M. Cicerone Endowment for NAS Missions for supporting the production of this 2020 Edition.

F OR FURTHER READING

For more detailed discussion of the topics addressed in this document (including references to the underlying original research), see:

• Intergovernmental Panel on Climate Change (IPCC), 2019: Special Report on the Ocean and Cryosphere in a Changing Climate [ https://www.ipcc.ch/srocc ]
• National Academies of Sciences, Engineering, and Medicine (NASEM), 2019: Negative Emissions Technologies and Reliable Sequestration: A Research Agenda [ https://www.nap.edu/catalog/25259 ]
• Royal Society, 2018: Greenhouse gas removal [ https://raeng.org.uk/greenhousegasremoval ]
• U.S. Global Change Research Program (USGCRP), 2018: Fourth National Climate Assessment Volume II: Impacts, Risks, and Adaptation in the United States [ https://nca2018.globalchange.gov ]
• IPCC, 2018: Global Warming of 1.5°C [ https://www.ipcc.ch/sr15 ]
• USGCRP, 2017: Fourth National Climate Assessment Volume I: Climate Science Special Reports [ https://science2017.globalchange.gov ]
• NASEM, 2016: Attribution of Extreme Weather Events in the Context of Climate Change [ https://www.nap.edu/catalog/21852 ]
• IPCC, 2013: Fifth Assessment Report (AR5) Working Group 1. Climate Change 2013: The Physical Science Basis [ https://www.ipcc.ch/report/ar5/wg1 ]
• NRC, 2013: Abrupt Impacts of Climate Change: Anticipating Surprises [ https://www.nap.edu/catalog/18373 ]
• NRC, 2011: Climate Stabilization Targets: Emissions, Concentrations, and Impacts Over Decades to Millennia [ https://www.nap.edu/catalog/12877 ]
• Royal Society 2010: Climate Change: A Summary of the Science [ https://royalsociety.org/topics-policy/publications/2010/climate-change-summary-science ]
• NRC, 2010: America’s Climate Choices: Advancing the Science of Climate Change [ https://www.nap.edu/catalog/12782 ]

Much of the original data underlying the scientific findings discussed here are available at:

• https://data.ucar.edu/
• https://climatedataguide.ucar.edu
• https://iridl.ldeo.columbia.edu
• https://ess-dive.lbl.gov/
• https://www.ncdc.noaa.gov/
• https://www.esrl.noaa.gov/gmd/ccgg/trends/
• http://scrippsco2.ucsd.edu
• http://hahana.soest.hawaii.edu/hot/

Climate change is one of the defining issues of our time. It is now more certain than ever, based on many lines of evidence, that humans are changing Earth's climate. The Royal Society and the US National Academy of Sciences, with their similar missions to promote the use of science to benefit society and to inform critical policy debates, produced the original Climate Change: Evidence and Causes in 2014. It was written and reviewed by a UK-US team of leading climate scientists. This new edition, prepared by the same author team, has been updated with the most recent climate data and scientific analyses, all of which reinforce our understanding of human-caused climate change.

Scientific information is a vital component for society to make informed decisions about how to reduce the magnitude of climate change and how to adapt to its impacts. This booklet serves as a key reference document for decision makers, policy makers, educators, and others seeking authoritative answers about the current state of climate-change science.

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Impact of climate change on the geographical distribution of ticks of public health significance in Colombia: Amblyomma ovale (Ixodida: Ixodidae), the Amblyomma maculatum (Ixodida: Ixodidae) complex and the Amblyomma cajennense (Ixodida: Ixodidae) complex

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Gina Polo, Jorge Gamarra, Laura Natalia Robayo-Sánchez, Jesús A Cortés-Vecino, Alejandro Ramírez-Hernández, Impact of climate change on the geographical distribution of ticks of public health significance in Colombia: Amblyomma ovale (Ixodida: Ixodidae), the Amblyomma maculatum (Ixodida: Ixodidae) complex and the Amblyomma cajennense (Ixodida: Ixodidae) complex, Journal of Medical Entomology , 2024;, tjae100, https://doi.org/10.1093/jme/tjae100

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Ticks of the Amblyomma maculatum  (Ixodida Ixodidae) complex, the Amblyomma cajennense (Ixodida Ixodidae) complex and Amblyomma ovale  (Ixodida Ixodidae) are known to transmit various Rickettsia species in Colombia, but their exact distribution is unknown. We built several models based on current climate and projected future climate changes using a maximum entropy approach. A total of 314 records of the A. cajennense complex (65.9%; n  = 207), A. ovale (22.9%; n  = 72), and the A. maculatum complex (11.1%; n  = 35) were obtained. Amblyomma ovale has a current distribution in the Pacific, Caribbean and Andean regions and could be potentially found in the Amazon. Amblyomma maculatum has a current distribution in the Andean and could potentially be found in the Caribbean and Orinoco regions. Amblyomma mixtum can be found near the Caribbean Sea and in the Pacific region, and A. patinoi is likely to be found in the Andean region and the Caribbean. In 2070, it will be possible to find an expansion of A. ovale and A. maculatum and a decrease of A. mixtum and A. patinoi . The variables that best predict the distribution of these species are isothermality (small fluctuations in temperature) and annual precipitation. Amblyomma cajennense s.l and A. ovale , A. cajennese s.l and A. patinoi , as well as A. maculatum and A. patinoi , have an important environmental sympatry. Epidemiological and acarological surveillance is crucial to investigate rickettsiosis caused by R. parkeri in A. ovale regions, by R. rickettsii in A. patinoi and A. mixtum areas, and by R. parkeri s.s in A. maculatum regions.

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Stakeholder Views on Citizen- Led Climate Change Policies in Malaysia for Climate-Resilient Communities

31 Pages Posted: 7 Sep 2024

Mufaro Chitsa

Universiti Teknologi PETRONAS

Malaysia is still progressing in raising awareness and education in climate change at the local level. With climate induced disasters still eminent in the country, an immediate need to educate the citizens on climate policy is a must. Supported by the Transtheoretical theory, this study aims at understanding how climate policy in Malaysia can be shaped by the citizen-led climate policy processes  through citizens’ active participation in climate policy making In this paper, a qualitative methodological approach through semi-structured interviews was employed to obtain the perspectives of climate change stakeholders. Responses from semi-structured interviews of stakeholders in climate change and environmental sectors, local governments and policy experts were analyzed to understand the current climate policy process, their successes, and shortfalls. Using NVivo software as an analysis tool, a robust analysis of the stakeholder interview transcripts was conducted to investigate the drivers for citizen participation in policy making. The study presents five main drivers for citizen participation in climate policy and their influence in citizen-led climate policies in Malaysia. This study proposes five interlinked drivers for citizen participation in policy making from a stakeholder viewpoint through a bottom-up approach targeting 1) positive climate friendly societal norms, 2) raising public awareness of policies 3) positive perceptions regarding climate change to 4) increase citizens’ self-efficacy to participate and contribute to policy  5) clearly organized participation processes. This study exerts the importance of citizen-led climate policy processes in Malaysia to assist in closing the gap in climate knowledge and education. Affording local citizens, the authority to deliberate and decide on climate change matters and policies that affect their communities, is one approach to policy democracy. Furthermore, incorporating citizen participation drivers in climate change policy and linking climate protection and civil society should be encouraged as effective local climate policy needs the participation of its citizens. Not much research has been conducted on citizen-led climate policy processes in Malaysia. This study thus provides insights and new climate policy paradigms for future policymakers and practitioners and a basis for comparative studies.

Keywords: Adaptation, Attitudes, Citizen Participation, Climate Change, Climate Policy, Community

Suggested Citation: Suggested Citation

Mufaro Chitsa (Contact Author)

Universiti teknologi petronas ( email ).

Research Scholar, Department of Chemical Engineeri Research Scholar, Department of Chemical Engineeri Perak Darul Ridzuan Malaysia

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