conduct a research work on global warming

The scientific method and climate change: How scientists know

By Holly Shaftel, NASA's Jet Propulsion Laboratory

The scientific method is the gold standard for exploring our natural world. You might have learned about it in grade school, but here’s a quick reminder: It’s the process that scientists use to understand everything from animal behavior to the forces that shape our planet—including climate change.

“The way science works is that I go out and study something, and maybe I collect data or write equations, or I run a big computer program,” said Josh Willis, principal investigator of NASA’s Oceans Melting Greenland (OMG) mission and oceanographer at NASA’s Jet Propulsion Laboratory. “And I use it to learn something about how the world works.”

Using the scientific method, scientists have shown that humans are extremely likely the dominant cause of today’s climate change. The story goes back to the late 1800s, but in 1958, for example, Charles Keeling of the Mauna Loa Observatory in Waimea, Hawaii, started taking meticulous measurements of carbon dioxide (CO 2 ) in the atmosphere, showing the first significant evidence of rapidly rising CO 2 levels and producing the Keeling Curve climate scientists know today.

“The way science works is that I go out and study something, and maybe I collect data or write equations, or I run a big computer program, and I use it to learn something about how the world works.”- Josh Willis, NASA oceanographer and Oceans Melting Greenland principal investigator

Since then, thousands of peer-reviewed scientific papers have come to the same conclusion about climate change, telling us that human activities emit greenhouse gases into the atmosphere, raising Earth’s average temperature and bringing a range of consequences to our ecosystems.

“The weight of all of this information taken together points to the single consistent fact that humans and our activity are warming the planet,” Willis said.

The scientific method’s steps

The exact steps of the scientific method can vary by discipline, but since we have only one Earth (and no “test” Earth), climate scientists follow a few general guidelines to better understand carbon dioxide levels, sea level rise, global temperature and more.

• Form a hypothesis (a statement that an experiment can test)
• Make observations (conduct experiments and gather data)
• Analyze and interpret the data
• Draw conclusions
• Publish results that can be validated with further experiments (rinse and repeat)

As you can see, the scientific method is iterative (repetitive), meaning that climate scientists are constantly making new discoveries about the world based on the building blocks of scientific knowledge.

“The weight of all of this information taken together points to the single consistent fact that humans and our activity are warming the planet." - Josh Willis, NASA oceanographer and Oceans Melting Greenland principal investigator

The scientific method at work.

How does the scientific method work in the real world of climate science? Let’s take NASA’s Oceans Melting Greenland (OMG) campaign, a multi-year survey of Greenland’s ice melt that’s paving the way for improved sea level rise estimates, as an example.

• Form a hypothesis OMG hypothesizes that the oceans are playing a major role in Greenland ice loss.
• Make observations Over a five-year period, OMG will survey Greenland by air and ship to collect ocean temperature and salinity (saltiness) data and take ice thinning measurements to help climate scientists better understand how the ice and warming ocean interact with each other. OMG will also collect data on the sea floor’s shape and depth, which determines how much warm water can reach any given glacier.
• Analyze and interpret data As the OMG crew and scientists collect data around 27,000 miles (over 43,000 kilometers) of Greenland coastline over that five-year period, each year scientists will analyze the data to see how much the oceans warmed or cooled and how the ice changed in response.
• Draw conclusions In one OMG study , scientists discovered that many Greenland glaciers extend deeper (some around 1,000 feet, or about 300 meters) beneath the ocean’s surface than once thought, making them quite vulnerable to the warming ocean. They also discovered that Greenland’s west coast is generally more vulnerable than its east coast.
• Publish results Scientists like Willis write up the results, send in the paper for peer review (a process in which other experts in the field anonymously critique the submission), and then those peers determine whether the information is correct and valuable enough to be published in an academic journal, such as Nature or Earth and Planetary Science Letters . Then it becomes another contribution to the well-substantiated body of climate change knowledge, which evolves and grows stronger as scientists gather and confirm more evidence. Other scientists can take that information further by conducting their own studies to better understand sea level rise.

All in all, the scientific method is “a way of going from observations to answers,” NASA terrestrial ecosystem scientist Erika Podest, based at JPL, said. It adds clarity to our way of thinking and shows that scientific knowledge is always evolving.

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Researching Climate Change

Climate change research involves numerous disciplines of Earth system science as well as technology, engineering, and programming. Some major areas of climate change research include water, energy, ecosystems, air quality, solar physics, glaciology, human health, wildfires, and land use.

To have a complete picture of how the climate changes and how these changes affect the Earth, scientists make direct measurements of climate using weather instruments. They also look at proxy data that gives us clues about climate conditions from prehistoric times. And they use models of the Earth system to predict how the climate will change in the future.

Measurements of modern climate change

Because climate describes the weather conditions averaged over a long period of time (typically 30 years), much of the same information gathered about weather is used to research climate. Temperature is measured every day at thousands of locations around the world. This data is used to calculate average global temperatures . Changes in temperature patterns are a strong indicator of how much the climate is changing. Because we have thousands of temperature measurements, we know that record high temperatures are increasing across the globe, which is a sign that the climate is warming. Climatologists also look at changes in precipitation, the length and frequency of drought, as well as the number of days that rivers are at flood stage to understand how the climate is changing. Winds and other direct measures of climate contribute to climate change research as well.

This map shows the location of weather stations across the Earth. Continuous data from thousands of stations is important for climate change research.

Using proxy data to understand climate change in the past

Throughout Earth's 4.6 billion years, the climate has changed drastically, including periods that were much colder and much warmer than the climate today. But how do we know about the climate from prehistoric times ? Researchers decipher clues within the Earth to help reconstruct past environments based on our understanding of environments today. Proxy data can take the form of fossils, sediment layers, tree rings , coral, and ice cores. These proxies contain evidence of past environments. For example, marine fossils and ocean seafloor sediment preserved in rock layers from around 80 million years ago (the Cretaceous Period) indicate that North America was mostly covered in water. The high sea levels were due to a much warmer climate when all of the polar ice sheets had melted. We also find fossil vegetation and pollen records indicating that forests covered the polar regions during this same time period. The existence of multiple types of proxy data from different locations, often from overlapping time periods, strengthens our understanding of past climates.

Ice core drilling in the Arctic provides proxy evidence of paleoclimate conditions.

National Snow and Ice Data Center

Using models to project future climate change

Scientists use models of the Earth to figure out how climate will likely change in the future. These models, which are simulations of Earth, include equations that describe everything from how the winds blow to how sea ice reflects sunlight and how forests take up carbon dioxide. In-depth knowledge of how each part of the Earth functions is needed to write the equations that represent each part within the model. Understanding climate change in both the present and the past helps to create computational models that can predict how the climate system might change in the future.

While scientists work hard to ensure that climate models are as accurate as possible, the models are unable to predict exactly how the climate will change in the future because some things are unknown, namely how much humans will change (or not change) behaviors that contribute to climate warming. Scientists run the models with different scenarios to account for a range of possibilities. For example, running the models to show how the climate will respond if we reduce fossil fuel emissions by different amounts can help us prepare for the many impacts that a changing climate has on the Earth.

Climate models keep track of how parameters change from place to place using a grid pattern on the Earth’s surface. The environmental conditions within each hexagon-shaped area are programmed into the model. More detailed models have smaller hexagons.

Studying the impacts of climate change

From monitoring changes in tropical coral reefs to changes in glacial ice, keeping track of how climate change is affecting the planet is important for adapting to the future. Scientists who monitor the environment report stronger and more frequent storms, changing weather patterns, a longer growing season in some locations, and changes in the distribution of plants and migratory animals. Monitoring how climate change is affecting our world can help identify new threats to human health as the ranges of insect-borne diseases change and as drought-prone regions expand.

Many different areas of research, from meteorology to oceanography, epidemiology to agriculture, and even fields such as sociology and economics, have a role to play in terms of researching both how the climate is changing and the impacts of climate change.

The average length of the growing season in the lower 48 states has increased by almost two weeks since the late 1800s, a result of the changing climate. Researchers study how this change in the growing season impacts humans and the Earth. Credit: EPA

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234 scientists read 14,000+ research papers to write the IPCC climate report – here’s what you need to know and why it’s a big deal

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Hundreds of scientists from around the world just released a new report assessing the state of the global climate. It’s a big deal. The report is used by governments and industries everywhere to understand the threats ahead.

So who are these scientists, and what goes into this important assessment?

Get ready for some acronyms. We’re going to take a closer look at how the IPCC report is made and some of the terms you’re hearing with the report’s release on Aug. 9, 2021.

What is the IPCC?

IPCC stands for Intergovernmental Panel on Climate Change. It’s the United Nations’ climate-science-focused organization. It’s been around since 1988, and it has 195 member countries.

Every seven years or so, the IPCC releases a report – essentially a “state of the climate” – summarizing the most up-to-date, peer-reviewed research on the science of climate change, its effects and ways to adapt to and mitigate it.

The purpose of these reports is to provide everyone, particularly governing bodies, with the information they need to make important decisions regarding climate change. The IPCC essentially provides governments with a CliffsNotes version of thousands of papers published regarding the science, risks, and social and economic components of climate change.

There are two important things to understand:

The IPCC reports are nonpartisan. Every IPCC country can nominate scientists to participate in the report-writing process, and there is an intense and transparent review process.

The IPCC doesn’t tell governments what to do. Its goal is to provide the latest knowledge on climate change, its future risks and options for reducing the rate of warming.

Why is this report such a big deal?

The last big IPCC assessment was released in 2013. A lot can change in eight years.

Not only has computer speed and climate modeling greatly improved, but each year scientists understand more and more about Earth’s climate system and the ways specific regions and people around the globe are changing and vulnerable to climate change.

Read more: IPCC climate report: Profound changes are underway in Earth's oceans and ice – a lead author explains what the warnings mean

Where does the research come from?

The IPCC doesn’t conduct its own climate-science research. Instead, it summarizes everyone else’s. Think: ridiculously impressive research paper.

The upcoming report was authored by 234 scientists nominated by IPCC member governments around the world. These scientists are leading Earth and climate science experts.

This report – the first of four that make up the IPCC’s Sixth Assessment Report – looks at the physical science behind climate change and its impacts. It alone will contain over 14,000 citations to existing research. The scientists looked at all of the climate-science-related research published through Jan. 31, 2021.

These scientists, who are not compensated for their time and effort, volunteered to read those 14,000-plus papers so you don’t have to. Instead, you can read their shorter chapters on the scientific consensus on topics like extreme weather or regional changes in sea-level rise.

The IPCC is also transparent about its review process , and that process is extensive. Drafts of the report are shared with other scientists, as well as with governments, for comments. Before publication, the 234 authors will have had to address over 75,000 comments on their work.

Government input to these bigger reports, like the one being released on Aug. 9, 2021, is solely limited to commenting on report drafts. However, governments do have a much stronger say in the shorter summary for policymakers that accompanies these reports, as they have to agree by consensus and typically get into detailed negotiations on the wording .

RCPs, SSPs – what does it all mean?

One thing just about everyone wants to understand is what the future might look like as the climate changes.

To get a glimpse of that future, scientists run experiments using computer models that simulate Earth’s climate. With these models, scientists can ask: If the globe heats up by a specific amount, what might happen in terms of sea-level rise, droughts and the ice sheets? What if the globe heats up by less than that – or more? What are the outcomes then?

The IPCC uses a set of scenarios to try to understand what the future might look like. This is where some of those acronyms come in.

All climate models work a little differently and create different results. But if 20 different climate models are run using the same assumptions about the amount of warming and produce similar results, people can be fairly confident in the results.

RCPs, or representative concentration pathways , and SSPs, or shared socioeconomic pathways , are the standardized scenarios that climate modelers use.

Four RCPs were the focus of the future-looking climate modeling studies incorporated into the 2013 report . They ranged from RCP 2.6, where there is a drastic reduction in global fossil fuel emissions and the world only heats up a little, to RCP 8.5, a world in which fossil fuel emissions are unfettered and the world heats up a lot.

This time around, climate modelers are using SSPs . Unlike the RCPs, which focus solely on greenhouse gas emissions trajectories, the SSPs consider socioeconomic factors and are concerned with how difficult it will be to adapt to or mitigate climate change, which in turn affects greenhouse gas emissions. The five SSPs differ in what the world might look like in terms of global demographics, equity, education, access to health, consumption, diet, fossil fuel use and geopolitics.

Why should you care?

Look around. Thus far, 2021 has brought deadly extreme weather events around the globe, from extensive wildfires to extreme heat, excessive rainfall and flash flooding. Events like these become more common in a warming world.

“It’s warming. It’s us. We’re sure. It’s bad. But we can fix it.” That’s how sustainability scientist and Lund University Professor Kimberly Nicholas puts it.

Read more: The water cycle is intensifying as the climate warms, IPCC report warns – that means more intense storms and flooding

Don’t expect an optimistic picture to emerge from the IPCC report. Climate change is a threat-multiplier that compounds other global, national and regional environmental and social issues.

So, read the report and recognize the major sources of greenhouse gases that are driving climate change. Individuals can take steps to reduce their emissions, including driving less, using energy-efficient lightbulbs and rethinking their food choices. But also understand that 20 fossil fuel companies are responsible for about one-third of all greenhouse gas emissions . That requires governments taking action now.

This article was updated Aug. 9, 2021, with the report release.

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Researchers who helped shape our understanding of climate change win Nobel Prize

Geoff Brumfiel

The Nobel Prize in physics went to three scientists this year for their work on climate change and chaotic systems.

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Yale and climate change: a world of research.

Yale’s solar array at West Campus has 4,400 panels, covering nearly two acres of rooftop.

In his first press conference after winning the 2018 Nobel Memorial Prize in Economics for his work connecting climate change to the global economy, Sterling Professor of Economics William Nordhaus took a moment to reflect on how Yale helps him address one of the world’s most pressing problems.

It came near the end of his remarks. Nordhaus paused at the podium and told the assembled reporters there was one more thing he needed to say. He talked about Yale’s commitment to recruiting excellent students and faculty, its tradition of nurturing big ideas, and its ability to create an environment of rigorous intellectual discussion.

“ One of the things that is underappreciated is the role of great institutions, or of institutions in general, in providing the support — not just financial support, but emotional support and intellectual support — for doing the kind of work that this prize recognizes,” he said.

Yale’s climate-change and environmental research is a clear case in point. Throughout the university, there are faculty, students, and staff fully engaged in analyzing the geophysical forces at play in global warming, developing and testing economic policies and behavioral tools that might reduce carbon emissions, exploring innovative technologies in energy production, carbon dioxide removal and clean water, collecting and evaluating hard data on the relationship between global warming and public health, and parsing the public’s ever-evolving opinions on climate change.

“ Home to multidisciplinary research, dynamic educational programs, and forums for convening diverse experts, Yale is uniquely positioned to help the world understand and mitigate climate change,” said President Peter Salovey. “We face an historic obligation to respond boldly, creatively, and meaningfully to build a more sustainable future.” Salovey has appointed a task force to determine how quickly Yale can reach its goal of net zero carbon emissions.

“ Climate change presents one of the great challenges of our time; to address it, we’re going to need creativity, expertise, and people who can think across disciplines and beyond boundaries,” said Indy Burke, the Carl W. Knobloch, Jr. Dean at the Yale School of Forestry & Environmental Studies (F&ES).

“ Yale scholars are at the forefront of research on climate change and are examining it from a wide range of perspectives,” Burke continued. “Whether they are studying its profound ecological, economic, and health implications, the costs and potential benefits of increasing urbanization, possible technical innovations, the critical carbon storage benefits provided by the world’s forests, or climate justice and the impacts on vulnerable populations, members of this community are producing world-leading research on this critical issue.”

Today Yale announced the formation of the Yale Carbon Offset Laboratory (COLAb), headed up by Dean Takahashi, who is stepping down from his role as senior director of the Yale Investments Office. COLAb will take a multidisciplinary approach to develop and support innovative technologies that sequester and store carbon and reduce greenhouse gas emissions on a large scale, with methods that can be tested and validated quickly and inexpensively.

The lab, based at F&ES, will aim to offset more than 1 billion tons of global carbon dioxide emissions over the long term, targeting more than 10 million tons in emissions offsets by 2030.

“ Yale is a place where we should be coming up with big ideas that have global impact,” Takahashi said in announcing COLab. “We want to find the kinds of projects that could reduce global carbon emissions safely at a large scale but at a low cost.”

From international indexes to a campus carbon charge

Nordhaus, considered by many to be the world’s leading economist on climate change, earned his Nobel for a body of work that treats carbon emissions and other aspects of climate change as important variables in the global economy. 

One concept often associated with Nordhaus is carbon pricing — a fixed price used as a way to account for carbon emissions within any plan for long-term economic growth. It would ultimately reduce carbon emissions, the theory goes, as manufacturers become motivated to find better alternatives to products that are carbon-based.

At Yale, Nordhaus chaired a task force that recommended Yale institute a carbon charge on campus. The Yale Carbon Charge, the first of its kind at a college or university, launched in 2017. Its work testing the impact of carbon pricing on emissions has been cited as a model for other institutions around the world.

“ Each month we share with campus financial managers and facilities superintendents an energy report that includes the financial impact of the carbon charge. Several have responded with initiatives to reduce energy consumption,” said Casey Pickett, director of the Carbon Charge. “We continue to learn from the carbon-charge experiment. It is making clearer which actors in the institution can access which levers of change to reduce carbon emissions.”

Likewise, Yale has drawn national and international attention from its involvement in other climate change initiatives:

• The Yale Program on Climate Change Communication (YPCCC), a research center within F&ES, has conducted groundbreaking work polling the American public on climate change. YPCCC, led by director Anthony Leiserowitz, has disseminated its research via a series of widely seen reports, videos, and innovative audio programs.
• The Environmental Performance Index (EPI) is a biennial report produced by researchers at Yale and Columbia Universities in collaboration with the World Economic Forum. Daniel C. Esty, director of the Yale Center for Environmental Law & Policy and the Hillhouse Professor at Yale, is the driving force behind EPI, which ranks countries on 24 performance indicators in 10 categories that cover environmental health and ecosystem vitality.
•  The Kerry Initiative at Yale, an interdisciplinary program led by former U.S. Secretary of State John Kerry, addresses global challenges via teaching, research, and dialogue. The Kerry Initiative hosted a Yale Climate Conference in 2017 that convened business, political, and diplomatic leaders to set a policy agenda for addressing climate change.
• The Max Planck-Yale Center for Biodiversity Movement and Global Change, founded in 2018, is bringing new technology and expertise to bear in advancing scientific knowledge of species movement through time. Walter Jetz, director of the Yale Center for Biodiversity and Global Change, is co-director of the center.
• The Yale Environmental Dialogue (YED), a new F&ES-based initiative, builds on the university’s ability to convene experts across disciplines to advance new climate strategies. YED is hosting a series of U.S. events, including during Climate Week in New York, to promote conversation on potential climate solutions. Next month, YED will publish a book, “A Better Planet: Forty Big Ideas for a Sustainable Future,” in which a range of experts propose new solutions, from utilizing the potential of genomics, to advancing solar-fuel technologies, to developing strategies for corporate sustainability, to building public will for new climate policies.

Putting the science in climate science

Yale researchers are also in the laboratory and the field making discoveries.

The Department of Geology and Geophysics (G&G) has been a hub of climate-change research. “I would say our biggest strengths, both historically and now, include research on the physics of how climate affects the circulation and heat budgets in the ocean, atmosphere, and cryosphere, which are all of the physics at the heart of climate predictions,” said David Bercovici, the Frederick W. Beinecke Professor of Geology and Geophysics and chair of G&G. “Another strength is research on the geochemistry of climate proxies, which are used to infer climate in the geological past. This is important for having observations and data for what Earth was like when it had CO2 levels similar to where we’re heading now, something not seen since 3 million years ago.”

Alexey Fedorov, professor of ocean and atmospheric sciences, received a 2018 Guggenheim Fellowship for his leading work on climate and ocean dynamics. His research into Arctic sea ice melting, El Nino events, and the Atlantic meridional overturning circulation has contributed a growing body of knowledge about how global warming may alter major climate systems.

In July, Mary-Louise Timmermans, professor and G&G director of undergraduate studies, received the President’s Early Career Award for Scientists and Engineers, the highest honor bestowed by the U.S. government to researchers who are beginning their independent research careers and who show exceptional promise for leadership in science and technology. Timmermans has done extensive work on Arctic Ocean heat and freshwater storage and transport in that region, including a 2018 study showing that warmer water had penetrated deep into the interior of the Arctic.

At Yale’s Energy Sciences Institute (ESI) on West Campus, a variety of disciplines converge to focus on environmental challenges. Directed by Gary Brudvig, the Benjamin Silliman Professor of Chemistry and professor of molecular biophysics and biochemistry, the center is exploring multiple approaches to finding new methods and materials for energy production and storage. ESI conducts research on solar energy, alternative fuels, and carbon mitigation, while tapping into expertise from Yale chemists, engineers, geologists, and physicists.

Menachem Elimelech, the Roberto Goizueta Professor of Chemical and Environmental Engineering at the School of Engineering and Applied Science, has made major strides in clean water research. Since coming to Yale in 1998, Elimelech has focused on water desalination technology, improving water and sanitation in developing countries, understanding the environmental implications of nanomaterials, and creating sustainable production of water and energy generation with engineered osmosis.

Meanwhile, F&ES remains another campus focal point for climate change research. For example, associate professor of industrial environmental management Marian Chertow is a co-principal investigator for an upcoming project that will look at whether humans can collaborate with robots to solve the “impurity” issues that threaten the global recycling industry.

Last year, F&ES introduced a new curriculum specialization for students on climate change science and solutions, which will focus on the science of climate change and effective ways to address it. The school also created a visiting professorship in climate change.

Other recent F&ES studies are looking at new ways to track the migration of salt marshes as a result of sea level rise, trends in global water usage, and an analysis of how storms and other factors influence the release of greenhouse gases from inland waters.

The Yale Center for Business and the Environment, a collaboration between F&ES and the Yale School of Management, trains future business and environmental sector leaders with an eye toward applying novel business solutions to systemic environmental problems.

Adding people to the equation

Some of Yale’s greatest strides in climate change research have involved the human element — ways in which global warming is affecting human health today and also how major climate events altered human behavior in the ancient past.

Since 2016, the Climate Change and Health Initiative (CCHI) at the Yale School of Public Health (YSPH) has taken a multidisciplinary approach to study different facets of the issue. “We see climate change as the biggest public health challenge of the 21 st century,” said Robert Dubrow, director of CCHI.

Dubrow said public health intersects with climate change at many points, from heat waves, air pollution, and drought to hurricanes that disrupt medical care for months or even years, to infectious diseases that spread because of flooded sewage systems or the presence of disease-carrying insects that are able to live in higher elevations that are becoming warmer.

Kai Chen, an assistant professor who joined CCHI this year, is conducting innovative research on the health effects of climate change and air pollution, as well as their interactive effects; Jodi Sherman, an associate professor of anesthesiology at the Yale School of Medicine and associate professor of epidemiology in environmental health sciences at YSPH, has gained attention for her work in uncovering the oversized environmental footprint of the healthcare sector and in making this sector more sustainable.

Last December, the university established the Yale Institute for Global Health (YIGH), a university-wide effort to address global health issues, including those affected by climate change. YIGH is led by the Schools of Medicine, Nursing, and Public Health, working with global partners to improve the health of populations worldwide.

In the Department of History, environmental historian Joseph Manning heads up an interdisciplinary project to study the link between climate change and human populations in the ancient world. Specifically, the National Science Foundation-funded project will look at how volcanic eruptions affected the Nile watershed in historic times, altering Egyptian history for 2,000 years.

The Yale Peabody Museum of Natural History, an administrator of the award, will develop a traveling exhibition program as part of the project.

Sustainable Yale

Yale’s on-campus sustainability efforts reflect the urgency of its relevant academic research.

President Salovey has formed a task force to examine how quickly the university can achieve net zero carbon emissions . In 2016, Yale set a goal to become carbon neutral by 2050, working with the Yale Office of Sustainability and a host of individual programs to take both immediate and long-term climate action. Those efforts range from nurturing new, progressive approaches to building design, to implementing smart irrigation systems, to piloting a “pay as you throw” program to encourage recycling and reduce waste.

Current work has yielded reductions in greenhouse gas emissions despite growth in campus size, but President Salovey noted that around the globe, carbon emissions are at an all-time high. “We have a responsibility to do more to create a better future and to show others how to address a problem we all share,” he said.

Yale also has a solar array at West Campus and plans to expand the use of solar on campus. The West Campus installation has 4,400 panels, covering nearly two acres of rooftop, and generates 1.6 million kilowatt-hours of electricity each year.

For the 2019-2020 academic year, Yale’s 14 residential colleges have adopted sustainability action plans tailored to each campus community. These come on the heels of action plans implemented by Yale’s professional schools and a number of departmental units in 2018.

“ Yale is committed to building a better world, and that includes the sustainability decisions we make here on campus as students, faculty, and staff,” said Virginia Chapman, director of the Yale Office of Sustainability. “We have ambitious sustainability goals, as outlined in our Yale Sustainability Plan 2025, which echoes the pathbreaking work being done by our research colleagues. This is the defining issue of our time.”

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You Asked: If the Science is Clear, Why Do We Need More Climate Research?

Charlotte Munson

“ You Asked ” is a series where Earth Institute experts tackle reader questions on science and sustainability. The following questions were submitted to climate scientist Gisela Winckler following her talk, “Reading the Ocean’s Diary: A Guide to our Climate Crisis.” In the talk, recorded as a part of the Lamont Doherty Earth Observatory’s 2020 Open House at Home, Winckler explains climate change in 12 words, lays out simple solutions, and shares some of the adventures she’s gone on while researching Earth’s past climate.

What is carbon neutrality and when do we need to achieve it?

Carbon neutrality is essentially having a balance between how much CO2 we emit and how much CO2 is being removed from the atmosphere in carbon sinks. What’s important to remember is that carbon neutrality doesn’t strictly mean no greenhouse gas emissions at all. Rather, it means that global emissions have to be counterbalanced by carbon removal. Those removal processes can include enhancing natural sinks, like restoring or planting new forests, or taking carbon directly out of the atmosphere and then storing it away, a process called carbon sequestration .

The Intergovernmental Panel on Climate Change report, which is based largely on models, says that in order to limit global warming to 1.5°C, we need to reach carbon neutrality by 2050. However, it’s one thing to say we need to be at net zero by 2050, and another to actually take steps to achieve the goal. We need to get there by reducing emissions, but we are still on an upward trajectory of emitting CO2. So, we need to shift to reducing our CO2 emissions, and we will only get there with systemic changes to how we use energy and what type of energy we use. Individual actions are good, but in order to reduce emissions at the global level necessary to limit global warming to 1.5°C, we need large-scale systemic changes.

If the science on climate change is already clear and simple, as you say in your talk, do we still need more climate research, or should we be focusing our resources on other things such as solutions?

The research into climate science is the foundation needed to actually think about solutions to climate change; they’re closely interconnected. Most of the solutions that we are talking about are grounded really in a fundamental understanding of the carbon cycle. By looking back into the past of the Earth, we are able to understand possible solutions, because the Earth has gone through a lot of these mechanisms on its own. We can actually learn from these natural processes, and then apply what we know from the processes in the past as a solution, by accelerating them all or scaling them up. It’s still the same mechanism. So, it’s not one or the other — climate research and solution development need to happen together. We need to focus on transdisciplinary work and prioritize communication between all fields that can play a role in understanding our climate system and developing solutions to climate change.

What worries you personally the most about climate change?

What worries me most is not actually what I talk about most, which is global mean temperatures rising. What worries me most is the thought of people suffering due to climate change. I worry about the human dimension of climate change. Changes in precipitation, such as where it rains and how much it rains, will greatly impact food production. I think the biggest threat from climate change will be feeding the planet. We’re already seeing impacts on agriculture and food production, and I think that will only get worse as climate change increases.

What does it feel like to go to the bottom of the ocean in a submarine?

It was truly the most exciting thing I’ve ever done, and I remember sort of feeling it through my whole body. There’s nothing that prepares you for it. You do all these practice drills before you actually go underwater. One of them is that you have to go into the submarine while it’s on deck and then they close the hatch, to give you that feeling. Once the hatch is closed, you can’t open it yourself, and that’s the moment where a few people change their minds! But I thought it was exciting. Once we start diving in the water, you’re at the surface, so there’s lots of light. You see all the life in the ocean around you. As you sink deeper in the water, it gets darker and darker and darker. It’s only the first few minutes of a dive that you actually have light, because only the upper 150 meters, maybe 200 meters have some detectable light.

It takes about an hour and a half to get to the bottom, so to preserve energy, all the lights are shut off. At some point we knew that we were 50 meters or 100 meters from the ocean floor, so we got really excited about reaching that point. Finally, we got to turn on these big, strong lights, and there was this huge octopus sitting on the ocean floor, right by where we were about to land! It was just very cool. I’m sure this guy had never seen anything like us. We spent several hours on the seafloor before we went back up, just observing everything. We found signs of gas hydrates and methane bubbles coming out of the seafloor, but we also noticed everything else. There are really weird looking creatures in the deep ocean!

What is the next expedition you’d like to take to continue your explorations?

There are so many places I’d like to explore! When I was in the Southern Ocean, we had lots of bad weather. We encountered a really strong storm system and couldn’t actually reach some of the target locations of the expedition. We were successful and lucky in getting almost everything done, but we never got to the most southern coring site. So, I’d love to go back there. I would also like to do a whole transect through the Pacific Ocean, from the north to the south. I’ve spent a lot of time at sea, which I love, but I would also like to go to Greenland or Antarctica. I’ve always wanted to be on an ice sheet!

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• Published: 09 February 2024

Globally representative evidence on the actual and perceived support for climate action

• Peter Andre   ORCID: orcid.org/0000-0002-8213-527X 1 ,
• Teodora Boneva   ORCID: orcid.org/0000-0002-4227-3686 2 ,
• Felix Chopra   ORCID: orcid.org/0000-0002-7621-1045 3 &
• Armin Falk   ORCID: orcid.org/0000-0002-7284-3002 2  

Nature Climate Change volume  14 ,  pages 253–259 ( 2024 ) Cite this article

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• Climate-change mitigation
• Psychology and behaviour

Mitigating climate change necessitates global cooperation, yet global data on individuals’ willingness to act remain scarce. In this study, we conducted a representative survey across 125 countries, interviewing nearly 130,000 individuals. Our findings reveal widespread support for climate action. Notably, 69% of the global population expresses a willingness to contribute 1% of their personal income, 86% endorse pro-climate social norms and 89% demand intensified political action. Countries facing heightened vulnerability to climate change show a particularly high willingness to contribute. Despite these encouraging statistics, we document that the world is in a state of pluralistic ignorance, wherein individuals around the globe systematically underestimate the willingness of their fellow citizens to act. This perception gap, combined with individuals showing conditionally cooperative behaviour, poses challenges to further climate action. Therefore, raising awareness about the broad global support for climate action becomes critically important in promoting a unified response to climate change.

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The world’s climate is a global common good and protecting it requires the cooperative effort of individuals across the globe. Consequently, the ‘human factor’ is critical and renders the behavioural science perspective on climate change indispensable for effective climate action. Despite its importance, limited knowledge exists regarding the willingness of the global population to cooperate and act against climate change 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . To fill this gap, we designed and conducted a globally representative survey in 125 countries, with the aim of examining the potential for successful global climate action. The central question we seek to answer is to what extent are individuals around the globe willing to contribute to the common good, and how do people perceive other people’s willingness to contribute (WTC)?

Drawing on a multidisciplinary literature on the foundations of cooperation, our study focuses on four aspects that have been identified as critical in promoting cooperation in the context of common goods: the individual willingness to make costly contributions, the approval of pro-climate norms, the demand for political action and beliefs about the support of others. We start with exploring the individual willingness to make costly contributions to act against climate change, which is particularly relevant given that cooperation is costly and involves free-rider incentives 9 . Using a behaviourally validated measure, we assess the extent to which individuals around the globe are willing to contribute a share of their income, and which factors predict the observed cross-country variation.

Furthermore, the provision of common goods crucially depends on the existence and enforcement of social norms. These norms prescribe cooperative behaviour 10 , 11 , 12 , 13 , 14 , 15 and affect behaviour either through internalization (shame and guilt 16 ) or the enforcement of norms by fellow citizens (sanctions and approval 17 ). In our survey, we elicit support for pro-climate social norms and examine the extent to which such norms have emerged globally.

It is widely recognized that addressing common-good problems effectively necessitates institutions and concerted political action 18 , 19 , 20 . In democracies, the implementation of effective climate policies relies on popular support, and even in non-democratic societies, leaders remain attentive to prevailing political demands. Therefore, we also elicit the demand for political action as a critical input in the fight against climate change 21 .

Previous research in the behavioural sciences has shown that many individuals can be characterized as conditional cooperators 22 , 23 , 24 , 25 , 26 . This means that individuals are more likely to contribute to the common good when they believe others also contribute. We test this central psychological mechanism of cooperation using our data on actual and perceived WTC. Moreover, we investigate whether beliefs about others’ WTC are well calibrated or whether they are systematically biased. If beliefs are overly pessimistic, this would imply that the world is in a state of pluralistic ignorance 27 , where systematic misperceptions about others’ WTC hinder cooperation and reinforce further pessimism. In such an equilibrium, correcting beliefs holds tremendous potential for fostering cooperation 28 , 29 , 30 , 31 .

The global survey

To obtain globally representative evidence on the willingness to act against climate change, we designed the Global Climate Change Survey. The survey was administered as part of the Gallup World Poll 2021/2022 in a large and diverse set of countries ( N  = 125) using a common sampling and survey methodology ( Methods ). The countries included in this study account for 96% of the world’s greenhouse gas (GHG) emissions, 96% of the world’s gross domestic product (GDP) and 92% of the global population. To ensure national representativeness, each country sample is randomly selected from the resident population aged 15 and above. Interviews were conducted via telephone (common in high-income countries) or face to face (common in low-income countries), with randomly drawn phone numbers or addresses. Most country samples include approximately 1,000 respondents, and the global sample comprises a total of 129,902 individuals.

To assess respondents’ willingness to incur a cost to act against climate change, we elicit their willingness to contribute a fraction of their income to climate action. More specifically, we ask respondents whether they would be ‘willing to contribute 1% of [their] household income every month to fight global warming’ (answered yes or no), and, if not, whether they would be willing to contribute a smaller amount (yes or no). To account for the substantial variation in income levels across countries, the question is framed in relative terms. Respondents’ answers thus reflect how strongly they value climate action relative to alternative uses of their income. The figure of 1% is deliberately chosen as it falls within the range of plausible previously reported estimates of climate change mitigation costs 32 , 33 .

Our WTC measure has been empirically validated and shown to predict incentivized pro-climate donation decisions ( Methods ). In a representative US sample 30 , respondents who state they would be willing to contribute 1% of their monthly income donate 43% more money to a climate charity ( P  < 0.001 for a two-sided t -test, N  = 1,993; Supplementary Fig. 1 ) and are 21–39 percentage points more likely to avoid fossil-fuel-based means of transport (car and plane), restrict their meat consumption, use renewable energy or adapt their shopping behaviour (all P  < 0.001 for two-sided t -tests, N  = 1,996; Supplementary Table 1 ).

To measure respondents’ beliefs about other people’s WTC, we first tell respondents that we are surveying many other individuals in their country about their willingness to contribute 1% of their household income every month to fight global warming. We then ask respondents to estimate how many out of 100 other individuals in their country would be willing to contribute this amount, that is, possible answers range from 0 to 100.

To assess individual approval of pro-climate social norms, we ask respondents to indicate whether they think that people in their country ‘should try to fight global warming’ (answered yes or no). Following recent research on social norms 15 , 34 , the item elicits respondents’ views about what other people should do, that is, what kind of behaviour they consider normatively appropriate (so-called injunctive norms 10 ).

Finally, we measure demand for political action by asking respondents whether they think that their ‘national government should do more to fight global warming’ (answered yes or no). This item assesses the extent to which individuals regard their government’s current efforts as insufficient and sheds light on the potential for increased political action in the future.

The approval of pro-climate norms and the demand for political action are deliberately measured in a general manner to account for the fact that suitable concrete mitigation strategies may differ across countries. Our general measures strongly correlate with the approval of specific pro-climate norms and the demand for concrete policy measures ( Methods ). In a representative US sample, individuals who approve of the general norm to act against climate change are substantially more likely to state that individuals ‘should try to’ avoid fossil-fuel-based means of transport (car and plane), restrict their meat consumption, use renewable energy or adapt their shopping behaviour (correlation coefficients ρ between 0.35 and 0.51, all P  < 0.001 for two-sided t -tests, N  = 1,994; Supplementary Table 2 ). Similarly, the general demand for more political action is strongly correlated with demand for specific climate policies, such as a carbon tax on fossil fuels, regulatory limits on the CO 2 emissions of coal-fired plants, or funding for research on renewable energy ( ρ between 0.49 and 0.59, all P  < 0.001 for two-sided t -tests, N  = 1,996; Supplementary Table 3 ).

To ensure comparability across countries and cultures, professional translators translated the survey into the local languages following best practices in survey translation by using an elaborate multi-step translation procedure. The survey was extensively pre-tested in multiple countries of diverse cultural heritage to ensure that respondents with different cultural, economic and educational backgrounds could comprehend the questions in a comparable way. We deliberately refer to ‘global warming’ rather than ‘climate change’ throughout the survey to prevent confusion with seasonal changes in weather 35 , 36 , and provide all respondents with a brief definition of global warming to ensure a common understanding of the term.

A list of variables, definitions and sources is available in Methods . In all analyses, we use Gallup’s sampling weights, which were calculated by Gallup in multiple stages. A probability weight factor (base weight) was constructed to correct for unequal selection probabilities resulting from the stratified random sampling procedure. At the next step, the base weights were post-stratified to adjust for non-response and to match the weighted sample totals to known population statistics. The standard demographic variables used for post-stratification are age, gender, education and region. When describing the data at the supranational level, we also weight each country sample by its share of the world population.

Widespread global support for climate action

The globally representative data reveal strong support for climate action around the world. First, a large majority of individuals—69%—state they would be willing to contribute 1% of their household income every month to fight global warming (Fig. 1a ). An additional 6% report they would be willing to contribute a smaller fraction of their income, and 26% state they would not be willing to contribute any amount. The proportion of respondents willing to contribute 1% of their income varies considerably across countries (Fig. 1b ), ranging from 30% to 93%. In the vast majority of countries (114 of 125) the proportion is greater than 50%, and in a large number of countries (81 of 125) the proportion is greater than two-thirds.

a , c , e , The global average proportions of respondents willing to contribute income ( a ), approving of pro-climate social norms ( c ) and demanding political action ( e ). Population-adjusted weights are used to ensure representativeness at the global level. b , d , f , World maps in which each country is coloured according to its proportion of respondents willing to contribute 1% of income ( b ), approving of pro-climate social norms ( d ) and demanding political action ( f ). Sampling weights are used to account for the stratified sampling procedure. Supplementary Table 4 presents the data. GW, global warming.

Second, we document widespread approval of pro-climate social norms in almost all countries. Overall, 86% of respondents state that people in their country should try to fight global warming (Fig. 1c ). In 119 of 125 countries, the proportion of supporters exceeds two-thirds (Fig. 1d ).

Third, we identify an almost universal global demand for intensified political action. Across the globe, 89% of respondents state that their national government should do more to fight global warming (Fig. 1e ). In more than half the countries in our sample, the demand for more government action exceeds 90% (Fig. 1f ).

Stronger willingness to contribute in vulnerable countries

Although the approval of pro-climate social norms and the demand for intensified political action is substantial in almost all countries (Fig. 1d,f ), there is considerable variation in the proportion of individuals willing to contribute 1% across countries (Fig. 1b ) and world regions (Supplementary Tables 4 and 5) . What explains the cross-country variation in individual WTC? Two patterns stand out.

First, there is a negative relationship between country-level WTC and (log) GDP per capita ( ρ  = −0.47; 95% confidence interval (CI), [−0.60, −0.32]; P  < 0.001 for a two-sided t -test; N  = 125; Fig. 2a ). To illustrate, in the wealthiest quintile of countries, the average proportion of people willing to contribute 1% is 62%, whereas it is 78% in the least wealthy quintile of countries. A country’s GDP per capita reflects its resilience, that is, its economic capacity to cope with climate change. Put differently, in countries that are most resilient, individuals are least willing to contribute 1% of their income to climate action. At the same time, a country’s GDP is strongly related to its current dependence on GHG emissions 37 . For the countries studied here, the correlation coefficient between log GDP and log GHG emissions is 0.87. From a behavioural science perspective, this pattern is consistent with the interpretation that individuals are less willing to contribute if they perceive the adaptation costs as too high, that is, when the required lifestyle changes are perceived as too drastic.

a – c , Binned scatter plots of the country-level proportion of individuals willing to contribute 1% of their income and log average GDP (per capita, purchasing power parity (PPP) adjusted) for 2010–2019 ( a ), annual average temperature (°C) for 2010–2019 ( b ) and the vulnerability index used in the IPCC Sixth Assessment Report (AR6) ( c ) 41 , 42 . The vulnerability index ranges from 0 to 100, with higher values indicating higher vulnerability. Correlation coefficients are calculated from the unbinned country-level data. We use sampling weights to derive the country-level WTC. Number of bins, 20; 6–7 countries per bin; derived from x axis. The red line represents linear regression.

Second, we find a positive relationship between country-level WTC and country-level annual average temperature ( ρ  = 0.35; 95% CI, [0.18, 0.49]; P  < 0.001 for a two-sided t -test, N  = 125; Fig. 2b ). The average proportion of people who are willing to contribute increases from 64% among the coldest quintile of countries to 77% among the warmest quintile of countries. Average annual temperature captures how exposed a country is to global warming risks 38 , 39 . Countries with higher annual temperatures have already experienced greater damage due to global warming, potentially making future threats from climate change more salient to their residents 40 .

Both results replicate in a joint multivariate regression and are robust to the inclusion of continent fixed effects and other economic, political, cultural or geographic factors (Supplementary Tables 6 – 9 ). Focusing on North America, we also find a significantly positive association between WTC and average temperature on the subnational level (Supplementary Fig. 2 ). Moreover, as low GDP and high temperatures constitute two important aspects of vulnerability to climate change, we also draw on a more comprehensive summary measure of vulnerability, derived for the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report 41 , 42 . In addition to national income and poverty levels, the index also takes into account non-economic factors, such as the quality of public infrastructure, health services and governance. It captures a country’s general lack of resilience and adaptive capacity, and it is highly correlated with log GDP ( ρ  = −0.93) and temperature ( ρ  = 0.62). Figure 2c confirms that people living in more vulnerable countries report a stronger WTC.

The country-level variation in pro-climate norms and demand for intensified political action is much smaller than that for the WTC. Nevertheless, we find that higher temperature predicts stronger norms and support for more political action. We do not detect a significant relationship with GDP (Supplementary Table 10 ).

Beliefs and systematic misperceptions

In line with previous research 11 , 22 , 23 , 24 , 25 , 26 , our data support the importance of conditional cooperation at the global level. Figure 3a shows a strong and positive correlation between the country-level proportions of individuals willing to contribute 1% and the corresponding average perceived proportions of fellow citizens willing to contribute 1% ( ρ  = 0.73; 95% CI, [0.64, 0.81]; P  < 0.001 for a two-sided t -test; N  = 125).

a , Binned scatter plots of the country-level proportions of individuals willing to contribute 1% of their income and the average perceived proportions of others who are willing to contribute 1% of their income. We use sampling weights to derive the country-level WTC and perceived WTC. Number of bins, 20; 6–7 countries per bin; derived from x axis. The red line shows the linear regression. b , Gap between the global and country proportions of respondents who are willing to contribute 1% of their income (circles) and the global and country average perceived proportions of others willing to contribute (triangles). The reported significance levels result from two-sided t -tests testing whether the proportion of individuals who are willing to contribute is equal to the average perceived proportion. We use population-adjusted weights to derive the global averages and the standard sampling weights otherwise. We derive the averages based on all available data, that is, we exclude missing responses separately for each question. See Supplementary Figure 4 for additional descriptive statistics for the perceived WTC (median, 25–75% quartile range).

We document the same pattern at the individual level. In a univariate linear regression analysis, a 1-percentage-point increase in the perceived proportion of others’ WTC is associated with a 0.46-percentage-point increase in one’s own probability of contributing (95% CI, [0.41, 0.50]; P  < 0.001; N  = 111,134; Supplementary Table 11 ). This effect size aligns closely with the degree of conditional cooperation that has been documented in the laboratory 26 .

The critical role of beliefs raises the question of whether beliefs are well calibrated. In fact, Fig. 3b reveals sizeable and systematic global misperceptions. At the global level, there is a 26-percentage-point gap (95% CI, [25.6, 26.0]; P  < 0.001 for a two-sided t -test; N  = 125; Supplementary Table 4 ) between the actual proportion of respondents who report being willing to contribute 1% of their income towards climate action (69%) and the average perceived proportion (43%). Put differently, individuals around the globe strongly underestimate their fellow citizens’ actual WTC to the common good. At the country level, the vast majority of respondents underestimate the actual proportion in their country (81%), and a large proportion of respondents underestimate the proportion by more than 10 percentage points (73%). This pattern holds for each country in our sample (Fig. 3b ). In all 125 countries, the average perceived proportion is lower than the actual proportion, significantly so in all but one country (two-sided t -tests, actual versus perceived WTC). If we limit the analysis to those respondents for whom we have non-missing data for both the actual and the perceived WTC, the global perception gap is estimated to be 29 percentage points (95% CI, [27.2, 30.0]; P  < 0.001 for a two-sided t -test; N  = 125; Supplementary Table 12 ), and the average perceived proportion is estimated to be significantly lower than the actual proportion in all 125 countries (Supplementary Fig. 3 ).

Although the perception gap is positive in all countries, we note that the size of the perception gap varies across countries (s.d. = 8.7 percentage points). Examining the same country-level characteristics as before, we find that the gap is significantly larger in countries with higher annual temperatures and significantly smaller in countries with high GDP (Supplementary Table 13 ). These results are largely robust to the inclusion of other economic, political or cultural factors, which we do not find to be significantly related to the perception gap. These findings are robust to only using respondents for whom we have non-missing data for both the actual and perceived WTC.

Climate scientists have stressed that immediate, concerted and determined action against climate change is necessary 32 , 41 , 43 , 44 . Against this backdrop, our study sheds light on people’s willingness to contribute to climate action around the world. What sets our study apart from existing cross-cultural studies on climate change perceptions 1 , 2 , 3 , 4 and policy views 4 , 5 , 6 is its globally representative coverage and its behavioural science perspective.

The results are encouraging. About two-thirds of the global population report being willing to incur a personal cost to fight climate change, and the overwhelming majority demands political action and supports pro-climate norms. This indicates that the world is united in its normative judgement about climate change and the need to act.

The four aspects of cooperation discussed in this article are likely to interact with one another. For example, consensus on pro-climate norms is likely to strengthen individuals’ WTC and vice versa 13 . Similarly, the enactment of climate policies is likely to strengthen climate norms and vice versa 45 . We find a strong positive correlation between the WTC, pro-climate norms, policy support and beliefs about others’ WTC across countries (Supplementary Table 14 ). Moreover, countries with a stronger approval of pro-climate social norms have passed significantly more climate-change-related laws and policies ( ρ  = 0.20; 95% CI, [0.02, 0.36]; P  = 0.028 for a two-sided t -test; N  = 122). These positive interactions suggest that a change in one factor can unlock potent, self-reinforcing feedback cycles, triggering social-tipping dynamics 46 , 47 . Our findings can inform system dynamics models and social climate models that explicitly take into account the interaction of human behaviour with natural, physical systems 48 , 49 .

The widespread willingness to act against climate change stands in contrast to the prevailing global pessimism regarding others’ willingness to act. The world is in a state of pluralistic ignorance, which occurs when people systematically misperceive the beliefs or attitudes held by others 27 , 28 , 29 , 30 , 31 , 50 . The reasons underlying this perception gap are probably multifaceted, encompassing factors such as media and public debates disproportionately emphasizing climate-sceptical minority opinions 51 , and the influence of interest groups’ campaigning efforts 52 , 53 . Moreover, during periods of transition, individuals may erroneously attribute the inadequate progress in addressing climate change to a persistent lack of individual support for climate-friendly actions 54 .

Importantly, these systematic perception gaps can form an obstacle to climate action. The prevailing pessimism regarding others’ support for climate action can deter individuals from engaging in climate action, thereby confirming the negative beliefs held by others. Therefore, our results suggest a potentially powerful intervention, that is, a concerted political and communicative effort to correct these misperceptions. In light of a global perception gap of 26 percentage points (Fig. 3b ) and the observation that a 1-percentage-point increase in the perceived proportion of others willing to contribute 1% is associated with a 0.46-percentage-point increase in one’s own probability to contribute (Supplementary Table 11 ), such an intervention may yield quantitatively large, positive effects. Rather than echoing the concerns of a vocal minority that opposes any form of climate action, we need to effectively communicate that the vast majority of people around the world are willing to act against climate change and expect their national government to act.

Sampling approach

The survey was carried out as part of the Gallup World Poll 2021/2022 in 125 countries, with a median total response duration of 30 min. The four questions were included towards the end of the Gallup World Poll survey and were timed to take about 1.5 min.

Each country sample is designed to be representative of the resident population aged 15 and above. The geographic coverage area from which the samples are drawn generally includes the entire country. Exceptions relate to areas where the safety of the surveyors could not be guaranteed or—in some countries—islands with a very small population.

Interviews are conducted in one of two modes: computer-assisted telephone interviews via landline or mobile phone or face to face (mostly computer assisted). Telephone interviews were used in countries with high telephone coverage, countries in which it is the customary survey methodology and countries in which the coronavirus disease 2019 pandemic ruled out a face-to-face approach. There is one exception: paper-and-pencil interviews had to be used in Afghanistan for 73% of respondents to minimize security concerns.

The selection of respondents is probability based. The concrete procedure depends on the survey mode. More details are available in the documentation of the Gallup World Poll ( https://news.gallup.com/poll/165404/world-poll-methodology.aspx ) 55 .

Telephone interviews involved random-digit dialling or sampling from nationally representative lists of phone numbers. If contacted via landline, one household member aged 15 or older is randomly selected. In countries with a landline or mobile telephone coverage of less than 80%, this procedure is also adopted for mobile telephone calls to improve coverage.

For face-to-face interviews, primary sampling units are identified (cluster of households, stratified by population size or geography). Within those units, a random-route strategy is used to select households. Within the chosen households, respondents are randomly selected.

Each potential respondent is contacted at least three (for face-to-face interviews) or five (telephone) times. If the initially sampled respondent can not be interviewed, a substitution method is used. The median country-level response rate corresponds to 65% for face-to-face interviews and 9% for telephone interviews. These response rates are comparatively high considering that survey participants are not offered financial incentives for participating in the Gallup World Poll. For telephone interviews, the Pew Research Center reports a response rate of 6% in the United States in 2019 ( https://pewrsr.ch/2XqxgTT ). For face-to-face interviews, ref. 56 found a non-response rate of 23.7% even in a country with very high levels of trust, such as Denmark.

The median and most common sample size is 1,000 respondents. An overview of survey modes and sample sizes can be found in Supplementary Table 15 .

Sampling weights

Although the sampling approach is probability based, some groups of respondents are more likely to be sampled by the sampling procedure. For instance, residents in larger households are less likely to be selected than residents in smaller households because both small and large households have an equal chance of being chosen. For this reason, Gallup constructs a probability weight factor (base weight) to correct for unequal selection probabilities. In a second step, the base weights are post-stratified to adjust for non-response and to match known population statistics. The standard demographic variables used for post-stratification are age, gender, education and region. In some countries, additional demographic information is used based on availability (for example, ethnicity or race in the United States). The weights range from 0.12 to 6.23, with a 10–90% quantile range of 0.28 to 2.10, ensuring that no observation is given an excessively disproportionate weight. Of all weights, 93% are between 0.25 and 4. More details are available in the documentation of the Gallup World Poll ( https://news.gallup.com/poll/165404/world-poll-methodology.aspx ) 55 .

We use these weights in our main analyses in two ways: first, when deriving national averages, we weight individual responses with Gallup’s sampling weights; and, second, when conducting individual-level regression analyses, we weight respondents with Gallup’s sampling weights.

We note that this weighting approach does not take into account the fact that some countries have a larger population than others. At the global level, the approach would effectively weight countries by their sample size and not their population size. Therefore, we also derive population-adjusted weights that render the data representative of the global population (aged ≥15) that is covered by our survey. The population-adjusted weight of individual i in country c is derived as

where w i c denotes the original Gallup sampling weight, I c the set of all respondents in country c , s c the country’s share of the global population aged ≥15 and n the total sample size of 129,902 respondents. Division by \({\sum }_{{I}_{c}}{w}_{ic}\) ensures that countries with a larger sample size (Supplementary Table 15 ) do not receive a larger weight. Multiplication with s c ensures that the total weight of a country sample is proportional to its population share. Multiplication with the constant n ensures that the total sum of the population-adjusted weights equals n , but is inconsequential for the results.

Although the two approaches yield very similar results (Supplementary Table 16 ), we use these population-adjusted weights wherever we present global statistics or statistics for supranational world regions. Supplementary Table 16 also shows that we obtain almost identical results if we do not use weights at all.

Global pre-test

A preliminary version of the survey was extensively pre-tested in 2020 in six countries of diverse cultural heritage—Colombia, Egypt, India, Indonesia, Kenya and Ukraine—to ensure that subjects from different cultural and economic backgrounds interpret the questions adequately. In each country, cognitive interviews were conducted by trained interviewers in local languages. The objectives of the pre-test were threefold, that is, to collect feedback, test whether the survey questions were understandable and check whether they were interpreted homogeneously across cultures. Each survey question was followed by additional probing questions that investigated respondents’ understanding of central terms and the overall logic of the question. Moreover, respondents were invited to express any comprehension difficulties. In response to the feedback, several minor adjustments to the survey were made. Most importantly, we switched to the term global warming instead of climate change to prevent confusion with seasonal changes in weather.

Survey items

The US English version of the questionnaire can be found below. Square brackets indicate information that is adjusted to each country. Parentheses indicate that a response option was available to the interviewer but not read aloud to the interviewee. The frequencies of missing data are summarized in Supplementary Table 17 .

Introduction to global warming

Now, on a different topic… The following questions are about global warming. Global warming means that the world’s average temperature has considerably increased over the past 150 years and may increase more in the future.

Willingness to contribute

Question 1 : Would you be willing to contribute 1% of your household income every month to fight global warming? This would mean that you would contribute [$1] for every [$100] of this income.

Responses : Yes, No, (DK), (Refused)

Coding : Binary dummy for Yes. (DK) and (Refused) are coded as missing data.

Question 2 (asked only if ‘No’ was selected in Question 1) : Would you be willing to contribute a smaller amount than 1% of your household income every month to fight global warming?

Responses : Yes, No, I would not contribute any income, (DK), (Refused)

Coding : We classify respondents into three categories based on their responses to both questions. Willing to contribute (at least) 1%, willing to contribute between 0% and 1%, not willing to contribute. We conservatively code (DK) and (Refused) in Question 2 as ‘Not willing to contribute’.

Beliefs about others’ willingness to contribute

Question : We are asking these questions to 100 other respondents in [the United States]. How many do you think are willing to contribute at least 1% of their household income every month to fight global warming?

Responses : 0–100, (DK), (Refused)

Coding : 0–100, (DK) and (Refused) are coded as missing data.

Social norms

Question : Do you think that people in [the United States] should try to fight global warming?

Demand for political action

Question : Do you think the national government should do more to fight global warming?

Note : We were not allowed to field this question in Myanmar, Saudi Arabia and the United Arab Emirates.

Implementation errors

In two countries, an implementation error was made for the question on WTC a proportion of income.

In Kyrgyzstan, 4 of 1,001 respondents answered the survey in the language Uzbek. To these four respondents, the second sentence of question 1 was not read. The other respondents in Kyrgyzstan were interviewed in a different language and were not affected.

In Mongolia, respondents were asked whether they are willing to contribute less than 1% in question 1. Of these respondents, 93.1% answered yes. We approximate the proportion of Mongolian respondents who are willing to contribute 1% as follows. The implementation error should not affect the proportion of respondents who answer no to both questions (4.4%). Moreover, we know that in most countries 5–6% of respondents are not willing to contribute 1% but are willing to contribute a positive amount smaller than 1%. This is also true in neighbouring countries of Mongolia (China, 6.0%; Kazakhstan, 4.9%; Russia, 5.6%). Therefore, we derive the proportion of Mongolian respondents who are willing to contribute 1% as 100% − 4.4% − 6% = 89.6%, which is close to the uncorrected proportion of 93.1%. Results are virtually unchanged if we exclude observations from Mongolia.

Translation

The translation process of the US English original version into other languages followed the TRAPD model, first developed for the European Social Survey 57 . The acronym TRAPD stands for translation, review, adjudication, pre-testing and documentation. It is a team-based approach to translation and has been found to provide more reliable results than alternative procedures, such as back-translation. The following procedure is implemented:

Translation: a local professional translator conducts the first translation.

Review: the translation is reviewed by another professional translator from an independent company. The reviewer identifies any issues, suggests alternative wordings and explains their comments in English.

Adjudication: the original translator receives this feedback and can accept or reject the suggestions. In the latter case, he provides an English explanation for his decision and a third expert adjudicates the disputed translation, which often involves further exchange with the translators.

Pre-testing: a pilot test with at least ten respondents per language is conducted.

Documentation: translations and commentary (Gallup internal) are documented.

The study was approved by the ethics committee of the Gallup World Poll. Informed consent was obtained from all human research participants.

Our main measures of support for climate action are deliberately measured in a general manner to account for the fact that suitable concrete strategies to act against climate change can differ widely across the globe. However, in previous work, we collected both the general measures and additional specific measures for the different facets of climate cooperation. We conducted a survey with a diverse sample of respondents that is representative of the US population in terms of the sociodemographic characteristics of age, gender, education and region 30 . Specifically, we first elicit respondents’ WTC, demand for political action and approval of pro-climate change norms. In a second step, respondents can allocate money between themselves and a pro-climate charity (incentivized). We also elicit whether respondents have engaged in a set of specific climate-friendly behaviours in the previous 12 months (answered yes or no). We further elicit whether they think that people in the United States should engage in these specific climate-friendly behaviours (yes or no). Finally, we measure support for specific climate-change-related policies and regulations using a four-point Likert scale. Supplementary Tables 1 – 3 show that our general measures are strongly correlated with concrete climate-friendly behaviours, concrete climate-friendly norms and support for specific climate-change-related policies and regulation. More details on these data can be found in ref. 30 .

The data in ref. 30 also allow us to investigate whether we obtain similar results using two different survey methodologies. The Gallup World Poll relies on computer-assisted telephone interviews (landline and mobile) and random sampling via random-digit dialling. In ref. 30 , an online survey was conducted and quota-based sampling was used. Reassuringly, we obtain very similar results for the proportion of the population willing to contribute 1% of their household income, supporting pro-climate norms and demanding more political action (Table 1 ).

Additional data sources

Annual temperature.

This is the annual average temperature (in degrees Celsius) from 2010 to 2019. The data are available from the World Bank Group’s Climate Change Knowledge Portal ( https://climateknowledgeportal.worldbank.org/download-data ) and derived from the CRU TS v.4.05 data ( https://crudata.uea.ac.uk/cru/data/hrg/ ).

A set of indicators for whether a country belongs to one of the following five continents: (1) Africa, (2) Americas, (3) Asia, (4) Europe and (5) Oceania.

Economic growth

The average GDP growth rate between 2000 and 2019, obtained by averaging the year-on-year change in real GDP per capita (in constant US dollars) across years (World Bank WDI database, https://databank.worldbank.org/source/world-development-indicators/Series/NY.GDP.PCAP.PP.KD ).

The average national GDP per capita from 2010 to 2019 in constant US dollars, adjusted for differences in purchasing power. To derive the percentage of world GDP that our survey represents, we take national GDP data from 2019. The data for each country are available from the World Bank WDI database ( https://databank.worldbank.org/source/world-development-indicators/Series/NY.GDP.PCAP.PP.KD ). For Taiwan and Venezuela, the World Bank does not provide GDP estimates. Instead, we use data from the International Monetary Fund World Economic Outlook Database ( https://www.imf.org/en/Publications/WEO/weo-database/2022/October ).

GHG emissions

The per-capita GHG emissions expressed in equivalent metric tons of CO 2 averaged from 2010 to 2019. To derive the percentage of world GHG emissions that our survey represents, we take national GHG data from 2019. GHGs include CO 2 (fossil only), CH 4 , N 2 O and F gases. Data are obtained from EDGAR v.7.0 (ref. 58 ).

Individualism–collectivism

This refers to a country’s location on the individualism–collectivism spectrum, which we standardize 59 .

Kinship tightness

This refers to the extent to which people are embedded in large, interconnected extended family networks. The measure is derived from the data of the Ethnographic Atlas in ref. 60 and is available at https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/JX1OIU .

Regional temperature

The population-weighted regional mean temperature in degrees Celsius (between 2010 and 2019). Regions are defined by Gallup and often coincide with the first administrative unit below the national level. We use temperature data from the Climatic Research Unit ( https://crudata.uea.ac.uk/cru/data/hrg/ ) and population data from the LandScan database ( https://www.ornl.gov/project/landscan ) to construct this variable.

Scientific articles

The average number of scientific articles (per capita) from 2009 to 2018. The annual data for each country are available from the World Bank WDI database and normalized with annual population data from the Maddison Project Database 2020 ( https://www.rug.nl/ggdc/historicaldevelopment/maddison/releases/maddison-project-database-2020 ).

Secondary and tertiary education

This refers to the proportion of the population with secondary or tertiary education as the highest level of education. The Gallup World Poll includes respondent-level information on whether the highest level of educational attainment is secondary and tertiary education, which we aggregate to national proportion by using Gallup’s sampling weights.

Survival versus self-expression values

The extent to which people in a country hold survival versus self-expression values, which we standardize. We obtain the data from the axes of the Inglehart–Welzel Cultural Map ( https://www.worldvaluessurvey.org/WVSNewsShow.jsp?ID=467 ) 61 .

Traditional versus secular values

The extent to which people in a country hold traditional versus secular values, which we standardize. We obtain the data from the axes of the Inglehart–Welzel Cultural Map ( https://www.worldvaluessurvey.org/WVSNewsShow.jsp?ID=467 ) 61 .

Vulnerability index

This measure captures a country’s vulnerability as defined in the IPCC Sixth Assessment Report 41 , 42 . Specifically, the measure is the average of the vulnerability subcomponent of the INFORM Risk Index and the WorldRiskIndex. The INFORM Risk Index consists of 32 indicators related to vulnerability and coping capacity. The vulnerability component of the WorldRiskIndex encompasses 23 indicators, which cover susceptibility, absence of coping ability and lack of adaptive capability. For example, the subcomponents include indicators of extreme poverty, food security, access to basic infrastructure, access to health care, health status and governance. The data and documentation are available at https://ipcc-browser.ipcc-data.org/browser/dataset?id=3736 .

Quality of governance standard data set 2021

The following variables are compiled from the Quality of Governance Standard Data Set 2021 ( https://www.gu.se/en/quality-government ) 62 .

Concentration of political power

This variable is based on the Political Constraints Index III from the Political Constraint Index (POLCON) Dataset ( https://mgmt.wharton.upenn.edu/faculty/heniszpolcon/polcondataset/ ), which we standardize.

A binary measure of democracy, obtained from ref. 63 .

Electricity from fossil fuels

The proportion of electricity produced from oil or coal (World Bank WDI database).

Perceived corruption

We use the Corruption Perception Index (0–100) from Transparency International ( https://www.transparency.org/en/cpi/ ), which we standardize.

The size of the population aged 15 or higher in 2019. The data are taken from the World Bank WDI database.

Property rights

The standardized score of the degree to which a country’s laws protect private property rights and the degree to which those laws are enforced (Heritage Foundation’s Index of Economic Freedom dataset; http://www.heritage.org/index/explore ).

Quality of Governance Environmental Indicators Dataset 2021

The following variables are compiled from the Quality of Governance Environmental Indicators Dataset 2021 ( https://www.gu.se/en/quality-government ) 64 .

Annual precipitation

The long-run average of annual precipitation (in mm per year) (World Bank WDI database).

Climate change executive policies

The cumulative number of climate-change-related policies or other executive provisions (from 1946 until 2020), which were published or decreed by the government, president or an equivalent executive authority ( https://climate-laws.org/ ) 65 .

Climate change laws and legislations

The cumulative number of climate-change-related laws and legislations (from 1946 until 2020) that were passed by the parliament or an equivalent legislative authority 65 .

Distance to coast

The average distance to the nearest ice-free coast (in 1,000 km) 66 .

Terrain ruggedness index

An index of the terrain ruggedness (as of 2012) originally developed to measure topographic variation 67 and modified by ref. 66 .

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.

Data availability

The data of the Global Climate Change Survey are available at https://doi.org/10.15185/gccs.1 . References to and the documentation of external and proprietary data, such as the Gallup World Poll data, are available in the Supplementary Information .

Code availability

The analysis code is available at https://doi.org/10.15185/gccs.1 .

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Acknowledgements

We thank S. Gächter, I. Haaland, L. Henkel, A. Oswald, C. Roth, E. Weber and J. Wohlfart for valuable comments. We thank M. Antony for his support in collecting and managing the Global Climate Change Survey data, and J. König, L. Michels, T. Reinheimer and U. Zamindii for excellent research assistance. Funding by the Institute on Behavior and Inequality (briq) (A.F.) and the Deutsche Forschungsgemeinschaft (DFG; through Excellence Strategy EXC 2126/1 390838866 (P.A., T.B. and A.F.) and through CRC TR 224) is gratefully acknowledged (P.A. and A.F.). The activities of the Center for Economic Behavior and Inequality (CEBI) are financed by the Danish National Research Foundation, grant DNRF134 (F.C.). We gratefully acknowledge research support from the Leibniz Institute for Financial Research SAFE (P.A.).

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Andre, P., Boneva, T., Chopra, F. et al. Globally representative evidence on the actual and perceived support for climate action. Nat. Clim. Chang. 14 , 253–259 (2024). https://doi.org/10.1038/s41558-024-01925-3

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Received : 13 July 2023

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DOI : https://doi.org/10.1038/s41558-024-01925-3

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Global warming.

The causes, effects, and complexities of global warming are important to understand so that we can fight for the health of our planet.

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Ash spews from a coal-fueled power plant in New Johnsonville, Tennessee, United States.

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Global warming is the long-term warming of the planet’s overall temperature. Though this warming trend has been going on for a long time, its pace has significantly increased in the last hundred years due to the burning of fossil fuels . As the human population has increased, so has the volume of fossil fuels burned. Fossil fuels include coal, oil, and natural gas, and burning them causes what is known as the “greenhouse effect” in Earth’s atmosphere.

The greenhouse effect is when the sun’s rays penetrate the atmosphere, but when that heat is reflected off the surface cannot escape back into space. Gases produced by the burning of fossil fuels prevent the heat from leaving the atmosphere. These greenhouse gasses are carbon dioxide , chlorofluorocarbons, water vapor , methane , and nitrous oxide . The excess heat in the atmosphere has caused the average global temperature to rise overtime, otherwise known as global warming.

Global warming has presented another issue called climate change. Sometimes these phrases are used interchangeably, however, they are different. Climate change refers to changes in weather patterns and growing seasons around the world. It also refers to sea level rise caused by the expansion of warmer seas and melting ice sheets and glaciers . Global warming causes climate change, which poses a serious threat to life on Earth in the forms of widespread flooding and extreme weather. Scientists continue to study global warming and its impact on Earth.

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• In Response to Climate Change, Citizens in Advanced Economies Are Willing To Alter How They Live and Work

Many doubt success of international efforts to reduce global warming

Table of contents.

• Acknowledgments
• Methodology

This analysis focuses on attitudes toward global climate change around the world. For this report, we conducted nationally representative Pew Research Center surveys of 16,254 adults from March 12 to May 26, 2021, in 16 advanced economies. All surveys were conducted over the phone with adults in Canada, Belgium, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, the UK, Australia, Japan, New Zealand, Singapore, South Korea and Taiwan.

In the United States, we surveyed 2,596 U.S. adults from Feb. 1 to 7, 2021. Everyone who took part in the U.S. survey is a member of the Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way nearly all adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories.

This study was conducted in countries where nationally representative telephone surveys are feasible. Due to the coronavirus outbreak, face-to-face interviewing is not currently possible in many parts of the world.

Here are the questions used for the report, along with responses. See our methodology database for more information about the survey methods outside the U.S. For respondents in the U.S., read more about the ATP’s methodology .

A new Pew Research Center survey in 17 advanced economies spanning North America, Europe and the Asia-Pacific region finds widespread concern about the personal impact of global climate change. Most citizens say they are willing to change how they live and work at least some to combat the effects of global warming, but whether their efforts will make an impact is unclear.

Citizens offer mixed reviews of how their societies have responded to climate change, and many question the efficacy of international efforts to stave off a global environmental crisis.

Conducted this past spring, before the summer season ushered in new wildfires , droughts , floods and stronger-than-usual storms , the study reveals a growing sense of personal threat from climate change among many of the publics polled. In Germany, for instance, the share that is “very concerned” about the personal ramifications of global warming has increased 19 percentage points since 2015 (from 18% to 37%).

In the study, only Japan (-8 points) saw a significant decline in the share of citizens deeply concerned about climate change. In the United States, views did not change significantly since 2015.

Young adults, who have been at the forefront of some of the most prominent climate change protests in recent years, are more concerned than their older counterparts about the personal impact of a warming planet in many publics surveyed. The widest age gap is found in Sweden, where 65% of 18- to 29-year-olds are at least somewhat concerned about the personal impacts of climate change in their lifetime, compared with just 25% of those 65 and older. Sizable age differences are also found in New Zealand, Australia, the U.S., France and Canada.

Public concern about climate change appears alongside a willingness to reduce its effects by taking personal steps. Majorities in each of the advanced economies surveyed say they are willing to make at least some changes in how they live and work to address the threat posed by global warming. And across all 17 publics polled, a median of 34% are willing to consider “a lot of changes” to daily life as a response to climate change.

Generally, those on the left of the political spectrum are more open than those on the right to taking personal steps to help reduce the effects of climate change. This is particularly true in the U.S., where citizens who identify with the ideological left are more than twice as willing as those on the ideological right (94% vs. 45%) to modify how they live and work for this reason. Other countries where those on the left and right are divided over whether to alter their lives and work in response to global warming include Canada, the Netherlands, Australia and Germany.

Beyond individual actions, the study reveals mixed views on the broader, collective response to climate change. In 12 of the 17 publics polled, half or more think their own society has done a good job dealing with global climate change. But only in Singapore (32%), Sweden (14%), Germany (14%), New Zealand (14%) and the United Kingdom (13%) do more than one-in-ten describe such efforts as “very good.” Meanwhile, fewer than half in Japan (49%), Italy (48%), the U.S. (47%), South Korea (46%) and Taiwan (45%) give their society’s climate response favorable marks.

Abroad, the U.S. response to climate change is generally seen as wanting. Among the 16 other advanced economies surveyed, only Singaporeans are slightly positive in their assessment of American efforts (53% say the U.S. is doing a “good job” of addressing climate change). Elsewhere judgments are harsher, with six-in-ten or more across Australia, New Zealand and many of the European publics polled saying the U.S. is doing a “bad job” of dealing with global warming. However, China fares substantially worse in terms of international public opinion: A median of 78% across 17 publics describe China’s handling of climate change as “bad,” including 45% who describe the Chinese response as “very bad.” That compares with a cumulative median of 61% who judge the American response as “bad.”

At the cross-national level, the European Union’s response to climate change is viewed favorably by majorities in each of the advanced economies surveyed, except Germany where opinion is split (49% good job; 47% bad job). However, there is still room for improvement, as only a median of 7% across the publics polled describe the EU’s efforts as “very good.” The United Nations’ actions to address global warming are also generally seen in a favorable light: A median of 56% say the multilateral organization is doing a good job. But again, the reviews are tempered, with just 5% describing the UN’s response to climate change as “very good.”

Publics in the advanced economies surveyed are divided as to whether actions by the international community can successfully reduce the effects of global warming. Overall, a median of 52% lack confidence that a multilateral response will succeed, compared with 46% who remain optimistic that nations can respond to the impact of climate change by working together. Skepticism of multilateral efforts is most pronounced in France (65%), Sweden (61%) and Belgium (60%), while optimism is most robust in South Korea (68%) and Singapore (66%).

These are among the findings of a new Pew Research Center survey, conducted from Feb. 1 to May 26, 2021, among 18,850 adults in 17 advanced economies.

People concerned climate change will harm them during their lifetimes

Many people across 17 advanced economies are concerned that global climate change will harm them personally at some point in their lifetime. A median of 72% express at least some concern that they will be personally harmed by climate change in their lifetimes, compared with medians of 19% and 11% who say they are not too or not at all concerned, respectively. The share who say they are very concerned climate change will harm them personally ranges from 15% in Sweden to 57% in Greece.

Roughly two-thirds of Canadians and six-in-ten Americans are worried climate change will harm them in their lifetimes. Only 12% of Canadians and 17% of Americans are not at all concerned about the personal impact of global climate change.

Publics in Europe express various degrees of concern for potential harm caused by climate change. Three-quarters or more of those in Greece, Spain, Italy, France and Germany say they are concerned that climate change will harm them at some point during their lives. Only in Sweden does less than a majority of adults express concern about climate change harming them. Indeed, 56% of Swedes are not concerned about personal harm related to climate change.

In general, Asia-Pacific publics express more worry about climate change causing them personal harm than not. The shares who express concern range from 64% in Australia to 88% in South Korea. About one-third or more in South Korea, Singapore and Australia say they are very concerned climate change will harm them personally.

The share who are very concerned climate change will harm them personally at some point during their lives has increased significantly since 2015 in nearly every country where trend data is available. In Germany, for example, the share who say they are very concerned has increased 19 percentage points over the past six years. Double-digit changes are also present in the UK (+18 points), Australia (+16), South Korea (+13) and Spain (+10). The only public where concern for the harm from climate change has decreased significantly since 2015 is Japan (-8 points).

While many worry climate change will harm them personally in the future, there is widespread sentiment that climate change is already affecting the world around them. In Pew Research Center surveys conducted in 2019 and 2020, a median of 70% across 20 publics surveyed said climate change is affecting where they live a great deal or some amount. And majorities in most countries included as part of a 26-nation survey in 2018 thought global climate change was a major threat to their own country (the same was true across all 14 countries surveyed in 2020 ).

Those who place themselves on the left of the ideological spectrum are more likely than those who place themselves on the right to be concerned global climate change will harm them personally during their lifetime. This pattern is present across all 14 nations where ideology is measured. In 10 of these 14, though, majorities across the ideological left, center and right are concerned climate change will harm them personally.

The difference is starkest in the U.S.: Liberals are 59 percentage points more likely than conservatives to express concern for this possibility (87% vs. 28%, respectively). However, large ideological differences are also present in Australia (with liberals 41 points more likely to say this), the Netherlands (+35), Canada (+30), Sweden (+30) and New Zealand (+23).

Women are more concerned than men that climate change will harm them personally in many of the publics polled. In Germany, women are 13 points more likely than men to be concerned that climate change will cause them harm (82% vs 69%, respectively). Double-digit differences are also present across several publics, including the U.S., Sweden, the UK, South Korea, Singapore, Taiwan, Australia and the Netherlands.

When this question was first asked in 2015 , women were also more likely to express concern than their male counterparts that climate change will harm them in the U.S., Germany, Canada, Japan, Spain and Australia.

Young people have been at the forefront of past protests seeking government action on climate change. In eight places surveyed, young adults ages 18 to 29 are more likely than those 65 and older to be concerned climate change will harm them during their lifetime. The difference is greatest in Sweden, home of youth climate activist Greta Thunberg . Young Swedes are 40 points more likely than their older counterparts to say they are concerned about harm from climate change. Large age gaps are also present in New Zealand (with younger adults 31 points more likely to say this), Australia (+30) and Singapore (+20). And young Americans, French, Canadians and Brits are also more likely to say that climate change will personally harm them in their lifetimes.

While large majorities across every age group in Greece and South Korea are concerned climate change will harm them personally, those ages 65 and older are more likely to hold this sentiment than those younger than 30.

Many across the world willing to change how they live and work to reduce effects of climate change

Many across the publics surveyed say they are willing to make at least some changes to the way they live and work to reduce the effects of climate change. A median of 80% across 17 publics say they would make at least some changes to their lives to reduce the effects of climate change, compared with a median of 19% who say they would make a few changes or no changes at all. The share willing to make a lot of changes ranges from 8% in Japan to 62% in Greece.

In North America, about three-quarters or more of both Canadians and Americans say they are willing to make changes to reduce the effects of climate change.

Large majorities across each of the European publics surveyed say they are willing to change personal behavior to address climate change, but the share who say they are willing to make a lot of changes varies considerably. About half or more in Greece, Italy and Spain say they would make a lot of changes, while fewer than a third in Belgium, Germany and the Netherlands say the same.

Majorities in each of the Asia-Pacific publics polled say they would make some or a lot of changes to how they live and work to combat the effects of climate change, including more than three-quarters in South Korea, Singapore, Australia and New Zealand. But in Japan, fully 44% say they are willing to make few or no changes to how they live and work to address climate change, the largest share of any public surveyed.

In eight countries surveyed, those ages 18 to 29 are more likely than those 65 and older to say they are willing to make at least some changes to how they live and work to help reduce the effects of climate change. In France, for example, about nine-in-ten of those younger than 30 are willing to make changes in response to climate change, compared with 62% of those 65 and older.

Ideologically, those on the left are more likely than those on the right to express willingness to change their behavior to help reduce the effects of global climate change. The ideological divide is widest in the U.S., where 94% of liberals say they are willing to make at least some changes to how they live and work to help reduce the effects of climate change, compared with 45% of conservatives. Large ideological differences are also present between those on the left and the right in Canada (a difference of 26 percentage points), the Netherlands (25 points), Australia (23 points) and Germany (22 points).

In most publics, those with more education are more likely than those with less education to say they are willing to adjust their lifestyles in response to the impact of climate change. 1 In Belgium, for example, those with a postsecondary degree or higher are 14 points more likely than those with a secondary education or below to say they are willing to make changes to the way they live. Double-digit differences are also present between those with more education and less education in France, Germany, New Zealand, the Netherlands and Australia.

And in most places surveyed, those with a higher-than-median income are more likely than those with a lower income to express willingness to make at least some changes to reduce the effects of climate change. For example, in Belgium, about three-quarters (76%) of those with a higher income say they would make changes to their lives, compared with 66% of those with a lower income.

Many are generally positive about how their society is handling climate change

Respondents give mostly positive responses when asked to reflect on how their own society is handling climate change. Around half or more in most places say they their society is doing at least a somewhat good job, with a median of 56% saying this across the 17 advanced economies.

Roughly two-thirds (64%) of Canadians say their country is doing a good job, while nearly half of Americans say the same.

In most of the European publics surveyed, majorities believe their nation’s climate change response is at least somewhat good. Those in Sweden and the UK are especially optimistic, with around seven-in-ten saying their society is doing a good job dealing with climate change. In Europe, Italians are the most critical of their country’s performance: 20% say their society is doing a very bad job, the largest share among all publics surveyed.

Around eight-in-ten in Singapore and New Zealand say their publics are doing a good job – the highest levels among all societies surveyed. This includes around a third (32%) in Singapore who say they are doing a very good job. Adults in the other Asia-Pacific publics surveyed are more circumspect; about half or fewer say their society is doing a good job.

Political ideology plays a role in how people evaluate their own public’s handling of climate change. For adults in 10 countries, those on the right tend to rate their country’s performance with regard to climate change more positively. The difference is most stark in Australia: 69% of those on the right say Australia is handling climate change well, compared with just 19% of those on the left – a 50-point difference. A striking difference also appears in the U.S., where conservatives are 41 points more likely than liberals to say the U.S. is doing a good job dealing with climate change.

Evaluations are also tied to how people view governing parties. In 10 of 17 publics surveyed, people who see the governing party positively are more likely than those with a negative view of the party to think climate change is being handled well. The opposite is true in the U.S., where only 33% of Democrats and Democratic-leaning independents say the U.S. is handling climate change well, compared with 61% of those who do not support the Democratic Party.

Mixed views on whether action by the international community can reduce the effects of climate change

Only a median of 46% across the publics polled are confident that actions taken by the international community will significantly reduce the effects of climate change. A median of 52% are not confident these actions will reduce the effects of climate change.

Canadians are generally divided on whether international climate action can reduce the impact of climate change. And 54% of Americans are not confident in the international community’s response to the climate crisis.

In Europe, majorities in Germany and the Netherlands express confidence that international climate action can significantly address climate change. However, majorities in France, Sweden, Belgium and Italy are not confident in climate actions taken by the international community.

South Koreans and Singaporeans say they are confident in international climate action, but elsewhere in the Asia-Pacific region, public opinion is either divided or leans toward pessimism about international efforts.

Opinion of international organizations, like the United Nations, is linked to confidence that actions taken by the international community will significantly reduce the effects of global climate change. Those with a favorable view of the UN are more confident that actions taken by the international community will significantly reduce the effects of climate change than those with an unfavorable view of the UN. This difference is largest in the U.S., where 61% with a favorable view of the UN say international action will reduce the effects of climate change, compared with just 22% of those with an unfavorable view of the organization. Double-digit differences are present in every public polled.

Similarly, in every EU member state included in the survey, those with favorable views of the bloc are more likely to have confidence in international efforts to combat climate change than those with unfavorable views.

Little consensus on whether international climate action will harm or benefit domestic economies

Relatively few in the advanced economies surveyed think actions taken by the international community to address climate change, such as the Paris climate agreement, will mostly benefit or harm their own economy. A median of 31% across 17 publics say these actions will be good for their economy, while a median of 24% believe such actions will mostly harm their economy. A median of 39% say actions like the Paris climate agreement will have no economic impact.

In Sweden, about half (51%) feel international climate actions will mostly benefit their economy. On the other hand, only 18% in France say their public will benefit economically from international climate agreements.

In no public do more than a third say international action on climate change will harm their economy. But in the U.S., which pulled out of the Paris climate agreement under former President Donald Trump and has just recently rejoined the accord under President Joe Biden, a third say international climate agreements will harm the economy. (For more on how international publics view Biden’s international policy actions, see “ America’s Image Abroad Rebounds With Transition From Trump to Biden .”)

The more widespread sentiment among those surveyed is that climate actions will have no impact on domestic economies. In eight publics, four-in-ten or more hold this opinion, including half in France. And in two places – Japan and Taiwan – one-in-five or more offer no opinion.

Those on the left of the ideological spectrum are more likely than those on the right to say international action to address climate change – such as the Paris Agreement – will mostly benefit their economies. U.S. respondents are particularly divided by ideology. Roughly half (53%) of liberals feel international actions related to climate change will benefit the U.S. economy, compared with just 12% of conservatives. The next largest difference is in Canada, where those on the left are 24 percentage points more likely than those on the right to think this type of international action will benefit their economy.

Those on the right in many publics are, in turn, more likely than those on the left to think international actions such as the Paris Agreement will mostly harm their economies. Here again, ideological divisions in the U.S. are much larger than those in other publics: 65% of conservatives say international climate change actions will harm the American economy, compared with 12% of liberals who say the same.

In several advanced economies, those who say their current economic situation is good are more likely to say that actions taken by the international community to address climate change will mostly benefit their economies than those who say the economic situation is bad. In Sweden, for example, a majority (55%) of those who say the current economic situation is good also believe international action like the Paris Agreement will benefit the Swedish economy, compared with 31% who are more negative about the state of the economy.

Evaluating the climate change response from the EU, UN, U.S. and China

In addition to reflecting on their own public, respondents were asked to evaluate how four international organizations or countries are handling global climate change. Of the entities asked about, the European Union receives the best ratings, with a median of 63% across the 17 publics surveyed saying the EU is doing a good job handling climate change. A median of 56% say the same for the United Nations. Far fewer believe the U.S. or China – the two leading nations in carbon dioxide emissions – are doing a good job.

EU handling of climate change receives high marks in and outside of Europe

Majorities in all but two of the publics surveyed think the EU is doing a good job addressing climate change. However, this positivity is tempered, with most respondents saying the EU’s effort is somewhat good, but few saying it is very good.

Praise for the bloc’s response to climate change is common among the European countries surveyed. In Spain and Greece, around seven-in-ten say the EU is doing at least a somewhat good job, and about six-in-ten or more in the UK, Italy, Sweden and France agree. The Dutch and Germans have more mixed feelings about how the EU is responding to climate change. Notably, only about one-in-ten say the EU is doing a very bad job handling climate change in every European country surveyed but Sweden, where only 5% say so.

Seven-in-ten Canadians believe the EU is doing a good job dealing with climate change, and 62% in the U.S. express the same view.

The Asia-Pacific publics surveyed report similarly positive attitudes on the EU’s climate plans. Around seven-in-ten Australians and Singaporeans consider the EU’s response to climate change at least somewhat good. About six-in-ten or more in New Zealand, South Korea, Japan and Taiwan echo this sentiment.

Climate change actions by UN seen positively among most surveyed

Majorities in most publics also consider the UN response to climate change to be good. A median of 49% across all publics surveyed say that the UN’s actions are somewhat good, and a median of 5% say the actions are very good.

Canadians evaluate the UN’s performance on climate more positively than Americans do. In Canada, roughly six-in-ten say the multilateral organization is doing at least a somewhat good job handling climate change. About half of those in the U.S. agree with that evaluation, with 43% of Americans saying the UN is doing a bad job of dealing with climate change.

In Europe, majorities in Spain, Sweden, the UK, Greece and Italy approve of how the UN is dealing with climate change. Fewer than half of adults in the Netherlands, France and Belgium agree with this evaluation, and only about a third in Germany say the same.

Singaporeans stand out as the greatest share of adults among those surveyed who see the UN’s handling of climate change as good. This includes 14% who say the UN response is very good, which is at least double the share in all other societies surveyed. Majorities in Australia and New Zealand similarly say that the UN is doing a good job.

Many critical of U.S. approach to climate change

In most publics surveyed, adults who say the U.S. is doing a good job of handling climate change are in the minority. A median of 33% say the U.S. is doing a somewhat good job, and a median of just 3% believe the U.S. is doing a very good job.

About half of Americans say their own country is doing a good job in dealing with global climate change, but six-in-ten Canadians say their southern neighbor is doing a bad job.

Across Europe, most think the U.S. is doing a bad job of addressing climate change, including 75% of Germans and Swedes. And at least a quarter in all European nations surveyed except the UK and Greece say the U.S. is doing a very bad job.

Singaporeans offer the U.S. approach to climate change the most praise in the Asia-Pacific region and across all publics surveyed; around half say they see the U.S. strategy positively. New Zealanders are the most critical in the Asia-Pacific region: Only about a quarter say the U.S. is doing at least a somewhat good job.

Political ideology is linked to evaluations of the U.S. climate strategy. In 12 countries, those on the right of the political spectrum are significantly more likely than those on the left to say the U.S. is doing a good job dealing with global climate change. The difference is greatest in Australia, Canada and Italy.

Few give China positive marks for handling of climate change

The publics surveyed are unenthusiastic about how China is dealing with climate change. A median of 18% across the publics say China is doing a good job, compared with a median of 78% who say the opposite. Notably, a median of 45% say that China is doing a very bad job handling climate change.

Just 18% of Americans and Canadians believe China is doing a good job handling climate change.

Similarly, few in Europe think China is dealing effectively with climate change. In fact, more than four-in-ten in nearly all European countries polled say China is doing a very bad job with regards to climate change. Criticism is less common in Greece, where a third give China positive marks for its climate change action.

Adults in the Asia-Pacific region also generally give China poor ratings for dealing with climate change. South Koreans are exceptionally critical; about two-thirds say China is doing a very bad job, the highest share in all publics surveyed. About four-in-ten or more in New Zealand, Japan and Australia concur. Singaporeans stand out, as half say China is doing a good job, nearly 20 percentage points higher than the next highest public.

In nine countries surveyed, those with less education are more positive toward China’s response to climate change than those with more education. Likewise, those with lower incomes are more inclined to provide positive evaluations of China’s climate change response. Those with less education or lower incomes are also less likely to provide a response in several publics.

CORRECTION (Oct. 13, 2021): In the chart “Publics are divided over the economic impact of international actions to address global climate change,” the “Don’t Know” column has been edited to reflect updated percentages to correct for a data tabulation error. These changes did not affect the report’s substantive findings.

• For the purpose of comparing educational groups across publics, education levels are standardized based on the UN’s International Standard Classification of Education (ISCED). The “less education” category is secondary education or below and the “more education” category is postsecondary or above in Australia, Belgium, Canada, Denmark, France, Germany, Italy, Japan, Netherlands, New Zealand, Singapore, South Korea, Spain, Sweden, Taiwan, UK and U.S. ↩

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What Five Graphs from the U.N. Climate Report Reveal About Our Path to Halting Climate Change

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It has been 8 years, one pandemic, and a slew of wildfires, storms, and heat waves since the last United Nations climate assessment report was released in 2013. During that time, 191 parties signed the Paris Agreement; the United States (the world’s second-largest emitter) left and reentered the agreement; renewable energy outpaced coal in the United States and all fossil fuels in Europe for the first time; and greenhouse gas emissions crashed worldwide during stay-at-home orders before springing back .

It is with this backdrop that the Intergovernmental Panel on Climate Change (IPCC) unveiled its new assessment of global climate science.

Started in 1988 by the U.N. Environment Programme and the World Meteorological Organization, the IPCC supplies policymakers with policy-neutral information about climate change. The IPCC does not conduct its own research­: It summarizes the work by global experts and notes where disagreements lie. More than 200 authors from 66 countries in the organization’s Working Group I wrote the latest report. The document includes more than 14,000 cited references. All eyes are turning to October’s U.N. Climate Change Conference of the Parties ( COP26 ) in Glasgow, Scotland, where the latest report will inform negotiations.

The report predicts that warming will reach 1.5°C by the early 2030s, exceeding the lower goal of the Paris Agreement . How much further the temperatures rise will depend on emissions. Each of the world’s top three emitters — China , the United States , and the European Union­ —have goals to slow the rate of emissions this decade.

The IPCC report spells out what could happen if we don’t meet these targets: The Arctic could be ice free by mid- to late century. Sea level could rise by a meter by 2100, inundating cities. And extreme heat waves could become more intense and frequent.

Here are five takeaways.

1. Global Warming Thus Far

The takeaway: The world has warmed 1.1°C compared to preindustrial levels, and regional hot spots already feel the heat, but we have not surpassed the Paris Agreement goal of limiting warming to 1.5°C or 2°C.

In the past 100,000 years, Earth has been this warm only once. Around 6,500 years ago, the planet’s temperatures were about on par with what they are today. The difference? That warming was part of an ebbing and flowing cycle of ice sheets from natural variation of Earth’s orbit. Today’s temperatures come from pollution that will continue to grow unless we hit the brakes.

Today, some areas on Earth have already warmed beyond 2°C. The Washington Post reported in 2019 that 71 counties in the United States have already warmed past 2°C. Temperatures in the Arctic are rising at least twice as fast as the rest of the world. Islands are particularly at risk: The rallying cry for 1.5°C originated from an alliance of 44 small island states that commissioned a study in 2008 and became alarmed that 2°C warming would threaten their survival.

Previous climate agreements favored a 2°C rise, but mounting evidence suggests that keeping temperatures to a 1.5°C rise would greatly reduce extreme heat, instances of extreme precipitation and drought, sea level rise, species loss and extinction, and ocean acidification.

Global temperatures have a 20% chance of reaching 1.5°C above preindustrial levels during at least one of the next five years, according to the U.K. Met Office and the World Meteorological Organization.

2. Future Warming Pathways

The takeaway: Keeping warming below 2°C, and perhaps 1.5°C, is still possible; it’ll take immediate and sustained emissions cuts.

Future illustrative scenarios of warming are one of the hallmarks of IPCC reports. The scenarios include natural forcing like solar activity and volcanoes, along with social and economic forces that drive greenhouse gas emissions, land use, climate mitigation, and air pollution.

The scenarios will underpin international policy, research, and activism for years to come.

The scenarios aren’t predictions; they can’t determine the fate of global warming. Instead, they provide road maps. The scenarios often underpin international policy, research, and activism for years to come.

The new report has five scenarios: two with low emissions, one with intermediate emissions, and two with high emissions. The very low emissions scenario meets the 1.5°C Paris Agreement goal with likely warming of 1.4°C by 2100—but it overshoots the target to just above 1.5°C midcentury before decreasing to 1.4°C. The low emissions scenario reaches 1.8°C by 2100, just skirting under the high bounds of the Paris Agreement. Midlevel emissions hit 2.7°C, high emissions clock in at 3.6°C, and very high emissions extend to 4.4°C in 2100.

Climate scientist and IPCC Working Group I cochair Valérie Masson-Delmotte said that the midlevel emissions scenario most closely resembles the pledges made by countries to plateau emissions until around 2030. The highest emissions scenarios represent futures without any climate mitigation.

The last IPCC assessment in 2013 included just one low emissions scenario that kept warming under 2°C.

3. Carbon Dioxide’s Oversized Footprint

The takeaway: Net zero carbon dioxide (CO 2 ) is a requirement for any long-term climate solution.

Greenhouse gases include CO 2 , methane, nitrous oxide, and fluorinated gases. When headlines or politicians talk about “net zero carbon” or “carbon neutral,” it may seem like they’re leaving out other greenhouse gases. But although most climate targets aim to reduce greenhouse gas emissions as a group, the essential ingredient is carbon dioxide.

The graph above illustrates why.

Warming is overwhelmingly controlled by the amount of carbon dioxide in the atmosphere. There is a nearly linear relationship between cumulative carbon dioxide increasing and global surface temperatures rising. The latest report even has an equation for it: Every 1,000 metric gigatons of cumulative CO 2 emissions (GtCO 2 ) will likely cause planetary warming of 0.45℃.

4. Annual Carbon Dioxide Emissions

The takeaway: The most aggressive scenario to limit warming requires sharp CO 2 cuts per decade, net zero CO 2 by 2050, and carbon capture.

Carbon emissions come from burning oil, gas, and coal; these fossil fuels drive heating, electricity, agriculture, land use, industry, and transport.

During COVID-19, emissions fell an unprecedented 2.6 GtCO 2 in 1 year , according to research published in Nature Climate Change in 2021. Because the emissions cuts during the pandemic were temporary, those reductions won’t have any detectable effect on CO 2 concentrations or temperature. The researchers of the Nature Climate Change study predict that emissions cuts of about this scale (1–2 GtCO 2 ) are necessary at least through the 2020s to meet the Paris Agreement.

5. Carbon Extraction

The takeaway: The two scenarios in the report that limit warming below 2°C use carbon removal from the atmosphere during the latter part of the century.

Carbon naturally cycles through the soil, water, plants, and air continuously. We can draw carbon out of the atmosphere by planting trees, sequestering carbon in agricultural soil, restoring ocean ecosystems that store carbon, and applying carbon capture and storage technology.

Model simulations in the latest report suggest that removing carbon dioxide from the atmosphere drops temperatures in just a matter of years.

Although some carbon removal methods show promise , the practice remains in the research and development phase and would require deployment at massive scales, according to the report. Carbon capture could cause undesirable effects such as losses of biodiversity, water, or food production.

More to Come

The report by Working Group I on the physical science is one of four expected over the next year; reports from Working Group II in February 2022 and Working Group III in March 2022 will explore the impacts of climate change and mitigation, respectively. The synthesis report in November 2022 will combine all findings.

—Jenessa Duncombe ( @jrdscience ), Staff Writer

Intergovernmental Panel on Climate Change (IPCC) (2021), Summary for policymakers, in Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change , edited by V. Masson-Delmotte et al., Cambridge Univ. Press, Cambridge, U.K., in press.

Duncombe, J. (2021), What five graphs from the U.N. climate report reveal about our path to halting climate change, Eos, 102 , https://doi.org/10.1029/2021EO161811 . Published on 09 August 2021.

Text © 2021. AGU. CC BY-NC-ND 3.0 Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

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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

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IGY Brings Many Discoveries

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Chilling possibilities

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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

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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

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Changing climate: 10 years after ‘An Inconvenient Truth’

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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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Global meta-analysis quantifies benefits of cover crop use

by Devin Voss, Indiana University

For years, both scientists and farmers have debated whether the use of cover crops—plants used to cover the ground after harvesting of main crops—have a positive or negative impact on subsequent crop yield. Hundreds of studies have been performed on the subject, with each resulting in a different conclusion.

Researchers at the Indiana University School of Science in Indianapolis compiled data from more than 100 field trials across the globe and found that cover crops have a net-positive impact, overall increasing crop yield by 2.6% globally. Standing out among the findings was how substantially yields benefited from the use of legumes as cover crops, including peas, vetch, and clover.

Yu Peng, a Ph.D. student in the School of Science, led a comprehensive study using literature synthesis and meta-analysis to quantify the results of the data gathered. Peng and his team collected over 1,000 records of field-based yield data and analyzed how cover crop type, soil texture, soil water conditions, aridity, cover crop duration, and other management practices impact crop yield.

"Studying in Indiana, surrounded by a rich agricultural heritage, I've witnessed firsthand challenges faced by farmers, including soil degradation and nutrient loss," Peng said. "This research aims to boost the adoption rate of cover crops by addressing farmer concerns about potential yield loss in the main crop, thereby benefiting agro-environments."

Leguminous cover crops showed a 9.8% yield increase compared to non-leguminous cover crops—like rye, oat, canola and mixture cover crops—which showed no statistical significance. Additionally, introducing leguminous cover crops without fertilizing main crops resulted in a 21.8% yield increase.

Corn, the most produced crop in the Midwest and the U.S., is one of two crops that benefit most from any kind of cover cropping, with an increased yield of 4.7%. Barley, another major U.S. crop, saw the most improved yield at 8.3%. Data suggests that by using leguminous cover cropping, yields could be even higher.

Researchers discovered that cover crops have the most benefit under nutrient-limited conditions. For instance, rainfed drylands had an increased yield from cover crops, whereas rainfed non-drylands saw no significant impact. Additionally, a 10.5% yield increase was observed when fertilizer wasn't used alongside cover cropping, but the yield increase dropped to 1.8% when combined with fertilizer treatment.

Coarser soils like sandy loam and loamy sand tended to increase yields under cover cropping. Conversely, fine-textured soils like clay-loam and clay soils saw a reduction under cover cropping, negatively impacting yield.

"Not every cover crop is suitable for every field management practice in every environment," Peng said. "My hope is this article leads to increased adoption and smarter cover cropping methods by offering comprehensive guidance in choosing optimal cover crop strategies based on their objectives, including the type of cover crops to use, which management practices to combine with and considerations of local meteorological factors."

Cover crops control soil erosion, increase soil moisture, improve soil structure and increase organic matter. Lixin Wang, a professor in the Department of Earth and Environmental Sciences and corresponding author on the study, said he hopes this work encourages more widespread adoption of cover crops, not only for the benefits it provides farmers but also for Earth's environment.

"Agriculture leaves a large environmental footprint," Wang said. "Often, it pollutes water and produces plenty of greenhouse gases. That's why we want to minimize the environmental impact while also ensuring we have a sufficient crop yield. We believe cover crops are a potential tool to help achieve this."

Agriculture is a vital part of Indiana's economic health. It's estimated that farming contributes $35.1 billion to Indiana's economy yearly. Farmland covers two-thirds of the state's total acreage. However, according to data from the Indiana State Department of Agriculture, less than 10% of Indiana farmers plant cover crops.

Currently, Peng is working with farmers in Fort Wayne, Indiana, to conduct field research of his own regarding cover crops, their use, and their impact on the local community. Overall, he has visions for a wide-scale series of research projects, tackling various nature-based agricultural solutions spanning from the corn-belt regions of the United States to a worldwide scale.

"After providing scientific evidence to farmers that using cover crops will benefit the environment without yield loss, the next frame explores what else it can contribute to," Peng said. "During my research, I always thought "You plant your corn and harvest it, but what else is there to think about?" Greenhouse gases could be one answer.

"If cover cropping proves effective in mitigating greenhouse gas emissions, it suggests that farmers could fight against global warming through a cost-effective and widely replicable approach."

The work is published in the journal Field Crops Research .

Provided by Indiana University

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Maximising technological solutions for a just transition in global value chains

Many organisations and countries aim to reach carbon-neutral or fully carbon-zero operations by 2050. However, the methods to achieve this goal require scrutiny, according to Bwana. To reach these goals, a lot more minerals are needed to build wind farms, solar panels. This means global value chains become impossible to avoid. ‘The transition minerals needed come from countries such as Indonesia (Nickel), Chile (lithium), Democratic Republic Congo (Cobalt). These countries strive for economic development through extraction and processing of these minerals. What must be ensured through all of this is that the people involved as well as the environment are treated fairly’, says Bwana.

A ‘just transition’

This fair treatment is what the International Labour Organization (ILO) calls a ‘just transition’. Bwana: ‘This means that achieving energy transition goals in the Global North shouldn’t come at the expense of the lives, livelihoods, and the environment in the Global South, where these minerals originate. Directives and regulations at the EU and member states levels aim to monitor value chains and ensure ethical treatment of people and the environment throughout. This is on top of industry-level agreements and guidelines from organisations such as the OECD.’

Technologies monitoring a just transition

The PhD student investigates the effectiveness of various digital technologies and tools in promoting this just transition. His research shows that different technologies serve different purposes in monitoring the just transition ‘These technologies must be used together to ensure the best outcome’, says the researcher. According to him, Blockchain is best suited for tracking mineral flow, while satellite-based technologies are optimal for monitoring environmental changes from above. Mobile apps are a good way to gather information from miners and factory workers about the conditions and challenges they face.

Technology alone is not enough

Bwana: ‘While all these developments can be praised, it should be noted that the adoption of these technologies alone is not enough to ensure a just transition. Human-provided information is influenced by personal motives, and individuals may only feel comfortable speaking up if they trust those operating the technology and are protected from potential repercussions. This is something that companies from across an ocean falling under a different legal jurisdiction may not be able to provide.

Fair access to information

Furthermore, we should ask where the information is going? ‘While companies may comply with European regulators, it's important to ensure that governments in the Global South also have reasonable access to information that could improve conditions in their countries’, says Bwana.

Reasonable expectations

He also emphasizes the notion of reasonable expectations. While companies engaging in unfair practices should face repercussions, doing business in resource-rich countries can come with the risk of illicit activities that companies may not be aware of. If repercussions are too severe, there is a risk that companies simply won’t conduct business there. This would deny the local population stable, well-paying jobs that could help improve livelihoods.

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