why is climate change a problem essay

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What is climate change and why does it matter?

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

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

What are weather, climate and climate change?

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

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

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

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

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

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

Causes of climate change

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

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

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

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

How do we know climate is changing?

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

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

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

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

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

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

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

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

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

Effects of climate change

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

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

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

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

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

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

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

The effects of climate change on us

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

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

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

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

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

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

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

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

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

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

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

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

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

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

How does climate change affect biodiversity?

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

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

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

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

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

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

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

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

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

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

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

Is there any hope for the future?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Causes and Effects of Climate Change

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

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

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Science News

Abdulhamid Hosbas/Anadolu Agency via Getty Images

Century of Science: Theme

Our climate change crisis

The climate change emergency.

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

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

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

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

Global average temperature change, 1850–2021

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

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

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

Tracking a Greenland glacier

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

The first climate scientists

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

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

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

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

Carbon floods in

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

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

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

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

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

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

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

The Keeling curve and climate change

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

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

Monthly average CO 2 concentrations at Mauna Loa Observatory

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

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

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

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

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

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

Environmental awareness grows

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

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

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

Climate change evidence piles up

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

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

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

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

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

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

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

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

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

Worrisome predictions from climate models

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

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

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

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

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

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

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

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

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

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

Climate science meets politics

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

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

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

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

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

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

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

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

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

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

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

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

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

The graph that launched climate skeptic attacks

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

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

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

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

Total carbon dioxide emissions by country, 1850–2021

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

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

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

Facing a warmer future

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

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

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

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

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

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

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

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

Historical and projected global temperature change

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

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

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

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

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

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

Time is running out. — Alexandra Witze

Climate change facts

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

How much has the planet warmed over the past century?

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

What is causing climate change?

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

What are some of the effects of climate change?

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

What is the greenhouse effect?

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

What is the Keeling curve?

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

Does it get hotter every year?

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

What countries emit the most carbon dioxide?

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

What places are impacted by climate change?

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

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

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

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

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

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

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

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

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

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

From the archive

Climate change foreseen.

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

IGY Brings Many Discoveries

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

Chilling possibilities

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

Long Hot Future: Warmer Earth Appears Inevitable

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

Ozone and Global Warming: What to Do?

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

Looking for Mr. Greenhouse

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

World Climate Panel Charts Path for Action

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

Animals on the Move

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

Changing climate: 10 years after ‘An Inconvenient Truth’

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

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

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

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

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

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

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

Extreme weather in 2022 showed the global impact of climate change

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

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

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

The last 12 months were the hottest on record

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

Science News is published by Society for Science

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Home / For Educators: Grades 6-12 / Climate Explained: Introductory Essays About Climate Change Topics

Climate Explained: Introductory Essays About Climate Change Topics

Filed under: backgrounders for educators ,.

Climate Explained, a part of Yale Climate Connections, is an essay collection that addresses an array of climate change questions and topics, including why it’s cold outside if global warming is real, how we know that humans are responsible for global warming, and the relationship between climate change and national security.

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Climate Change Basics: Five Facts, Ten Words

Backgrounders for Educators

To simplify the scientific complexity of climate change, we focus on communicating five key facts about climate change that everyone should know. 

Why should we care about climate change?

Having different perspectives about global warming is natural, but the most important thing that anyone should know about climate change is why it matters.  

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Responding to the Climate Threat: Essays on Humanity’s Greatest Challenge

A new book co-authored by MIT Joint Program Founding Co-Director Emeritus Henry Jacoby

From the Back Cover

This book demonstrates how robust and evolving science can be relevant to public discourse about climate policy. Fighting climate change is the ultimate societal challenge, and the difficulty is not just in the wrenching adjustments required to cut greenhouse emissions and to respond to change already under way. A second and equally important difficulty is ensuring widespread public understanding of the natural and social science. This understanding is essential for an effective risk management strategy at a planetary scale. The scientific, economic, and policy aspects of climate change are already a challenge to communicate, without factoring in the distractions and deflections from organized programs of misinformation and denial. 

Here, four scholars, each with decades of research on the climate threat, take on the task of explaining our current understanding of the climate threat and what can be done about it, in lay language―importantly, without losing critical  aspects of the natural and social science. In a series of essays, published during the 2020 presidential election, the COVID pandemic, and through the fall of 2021, they explain the essential components of the challenge, countering the forces of distrust of the science and opposition to a vigorous national response.  

Each of the essays provides an opportunity to learn about a particular aspect of climate science and policy within the complex context of current events. The overall volume is more than the sum of its individual articles. Proceeding each essay is an explanation of the context in which it was written, followed by observation of what has happened since its first publication. In addition to its discussion of topical issues in modern climate science, the book also explores science communication to a broad audience. Its authors are not only scientists – they are also teachers, using current events to teach when people are listening. For preserving Earth’s planetary life support system, science and teaching are essential. Advancing both is an unending task.

About the Authors

Gary Yohe is the Huffington Foundation Professor of Economics and Environmental Studies, Emeritus, at Wesleyan University in Connecticut. He served as convening lead author for multiple chapters and the Synthesis Report for the IPCC from 1990 through 2014 and was vice-chair of the Third U.S. National Climate Assessment.

Henry Jacoby is the William F. Pounds Professor of Management, Emeritus, in the MIT Sloan School of Management and former co-director of the MIT Joint Program on the Science and Policy of Global Change, which is focused on the integration of the natural and social sciences and policy analysis in application to the threat of global climate change.

Richard Richels directed climate change research at the Electric Power Research Institute (EPRI). He served as lead author for multiple chapters of the IPCC in the areas of mitigation, impacts and adaptation from 1992 through 2014. He also served on the National Assessment Synthesis Team for the first U.S. National Climate Assessment.

Ben Santer is a climate scientist and John D. and Catherine T. MacArthur Fellow. He contributed to all six IPCC reports. He was the lead author of Chapter 8 of the 1995 IPCC report which concluded that “the balance of evidence suggests a discernible human influence on global climate”. He is currently a Visiting Researcher at UCLA’s Joint Institute for Regional Earth System Science & Engineering.

Access the Book

View the book on the publisher's website  here .

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10 reasons why climate change is an important issue

We’re all concerned about climate change, but when it looks like a problem for future generations, you ask yourself, ‘will climate change even affect me?’ No matter what you care about, climate change is already affecting our world today. While we still have time to limit the worst impact, here are ten great reasons why we should all care about climate change:

Climate change will mean big changes for animals around the world. So if we care about incredible species, we must care about how a changing climate will make it harder for them to find food, and decrease their habitats – from forest to sea ice to the UK’s rivers and chalk streams .

2. Because you need your morning coffee fix

If you’re one of those people who need a coffee hit to get going, mornings may become grim. The effects of climate change on coffee are well-documented and coffee producers are already seeing reduced harvests, and more pests, because of it. Even if you’re caffeine-free you’re not in the clear – wine production may also be hit.

Finding Nemo or Dory may become harder as their beautiful homes crumble under the stress of our changing climate. Warmer air and ocean temperatures cause coral bleaching, where corals lose their colour and may die. Ocean acidification – from increased CO2 in the atmosphere – compounds the problem. Today, the ocean is 26% more acidic than it was in 1990, and the Great Barrier Reef has just experienced unprecedented back-to-back bleaching events in 2016 and 2017. Climate change is very bad news for anyone hoping to see the Great Barrier Reef one day.

4. Because we all need clean water

Did you know that 2 in every 3 people worldwide live in regions of severe water scarcity? Even a small increase in global temperatures will destabilise the water cycle and could make water scarcity much worse. Climate change affects rainfall patterns, meaning both drought and flooding will be more common, and more intense. And although it’s hardly comparable with life-threatening floods, climate change may already be making you late for work .

Globally temperature records  have been broken in recent years, and flooding in the UK gets worse. Year after year we’ve seen politicians wading through floods in Somerset, hopping into dinghies in Cornwall and arguing with each other in Westminster. More frequent and more intense extreme weather is a documented result of our greenhouse gas emissions, and the annual cost of flooding in the UK could increase 15-fold by the 2080s. We need to see politicians taking serious action on reducing the UK's carbon footprint, not looking for the next photo opportunity.

6. Because rainforests are incredible

Unique, irreplaceable, and often described as ‘the world’s lungs’, rainforests are some of the most precious habitats on the planet. They really are amazing; the Amazon, for example, is home to an astonishing 1 in 10 of all the known species on Earth. Yet over a third of the Amazon rainforest is already threatened by climate change. It’s a double-edged sword too: worldwide, forest destruction – mainly for agriculture – is a major cause of climate change, generating an incredible amount of greenhouse gases.

With increasing carbon emissions, it stands to reason that we face compromised air quality. This affects human health, especially children. Air pollution can lead to asthma, heart and lung disease. Beijing’s insidious smog is a visible reminder of this, but bad air quality is also making headlines in the UK, and has been labelled a ‘public health emergency’ by MPs.

8. Because clean tech is exciting

It’s not all bad news. Some of the biggest advancements in technology over the past few years have come from trying to limit, and come up with alternatives to, humanity’s CO2 dependency. Solar panels, wave-energy conversion and wind farms are allowing us to harness the power of nature in a clean way, harvesting energy without harming our environment or destroying habitats. Meanwhile nifty gadgets – like the Wall-E sized robot that can insulate your house to save energy – are helping to cut carbon in unexpected places. More of this technology could mean a cleaner, healthier future for us and our planet – because clean tech doesn’t just help nature, it also has the potential to build better, more accessible and people-friendly cities.

Climate change won’t just impact forest, or coral reefs, or even people in far-off countries – it will affect all of us. From more extreme weather to increasing food prices, to recreation and decreased opportunities to appreciate the natural world, people everywhere will feel its effects. Reducing our carbon footprint is fundamentally necessary to create a world where people and nature thrive – and that’s why WWF is working on it .

10. Because of future generations

We are fortunate to live in a beautiful, diverse, nurturing, awe-inspiring planet. Our children, and all future generations, deserve the same.

If you’re feeling worried by now, you’re not alone. Millions of people are working together for our planet. Events like Earth Hour are a brilliant reminder that together, humanity is capable of great things, and we can make change happen for the right reasons.

Already, so much has changed since we first heard about the possible effect of climate change. Beginning with the Rio Earth Summit, then the Kyoto Protocol and the Paris Agreement, action on a global scale is speeding up. Now it is more important than ever that we use our action, our votes and our voices to tell political and business leaders that action on climate is absolutely essential.

What can you do? You could start with taking our carbon footprint calculator, to look at how your lifestyle impacts the environment and where you can reduce your footprint.

• EO Explorer

• Global Maps

Climate Q&A

Why is global warming a problem.

The cost and benefits of global warming will vary greatly from area to area. For moderate climate change, the balance can be difficult to assess. But the larger the change in climate, the more negative the consequences will become. Global warming will probably make life harder, not easier, for most people. This is mainly because we have already built enormous infrastructure based on the climate we now have.

People in some temperate zones may benefit from milder winters, more abundant rainfall, and expanding crop production zones. But people in other areas will suffer from increased heat waves, coastal erosion, rising sea level, more erratic rainfall, and droughts.

The crops, natural vegetation, and domesticated and wild animals (including seafood) that sustain people in a given area may be unable to adapt to local or regional changes in climate. The ranges of diseases and insect pests that are limited by temperature may expand, if other environmental conditions are also favorable.

The problems seem especially obvious in cases where current societal trends appear to be on a “collision course” with predictions of global warming’s impacts:

• at the same time that sea levels are rising, human population continues to grow most rapidly in flood-vulnerable, low-lying coastal zones ;
• places where famine and food insecurity are greatest in today’s world are not places where milder winters will boost crop or vegetation productivity, but instead, are places where rainfall will probably become less reliable , and crop productivity is expected to fall;
• the countries most vulnerable to global warming’s most serious side effects are among the poorest and least able to pay for the medical and social services and technological solutions that will be needed to adapt to climate change.

In its summary report on the impacts of climate change, the Intergovernmental Panel on Climate Change stated, “Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time.”

(For specific information on the projected impacts of climate change in the United States, see the National Assessment Report by the U.S. Global Change Research Program.)

Related Resources

• United Nations Environment Programme, Division of Early Warning and Assessment. (2006). Emerging Challenges: New Findings, in P. Harrison (Ed.), Global Environment Outlook Year Book 2006 (59-70). Malta: Progress Press Ltd.
• McGranahan, G., Balk, D., and Anderson, B. (2007) The rising tide: assessing the risks of climate change and human settlements in low elevation costal zones. Environment and Urbanization, 19 (1), 17-37.
• Intergovernmental Panel on Climate Change. (2007). Summary for Policy Makers. In Climate Change 2007: Impacts, Adaptation and Vulnerability, Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller (eds.)]. Cambridge, United Kingdom, and New York, New York: Cambridge University Press.

This entry was posted on Tuesday, July 6th, 2010 at 3:45 pm and is filed under Climate , Global Warming: Impacts . You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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• Climate: Greenhouse Gases
• Climate: Human Impact
• Climate: Sun-Earth
• Global Warming
• Global Warming: Causes
• Global Warming: Controlling
• Global Warming: Impacts
• Global Warming: Myths
• Observations

What Is Climate Change?

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

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

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

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

What Is Global Warming?

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

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

Weather vs. Climate

“if you don’t like the weather in new england, just wait a few minutes.” - mark twain.

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

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

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

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

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

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

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

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

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

Other NASA Resources

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

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

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

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

Discover More Topics From NASA

Explore Earth Science

Earth Science in Action

Earth Science Data

Facts About Earth

Newsroom Post

Climate change: a threat to human wellbeing and health of the planet. taking action now can secure our future.

BERLIN, Feb 28 – Human-induced climate change is causing dangerous and widespread disruption in nature and affecting the lives of billions of people around the world, despite efforts to reduce the risks. People and ecosystems least able to cope are being hardest hit, said scientists in the latest Intergovernmental Panel on Climate Change (IPCC) report, released today.

“This report is a dire warning about the consequences of inaction,” said Hoesung Lee, Chair of the IPCC. “It shows that climate change is a grave and mounting threat to our wellbeing and a healthy planet. Our actions today will shape how people adapt and nature responds to increasing climate risks.”

The world faces unavoidable multiple climate hazards over the next two decades with global warming of 1.5°C (2.7°F). Even temporarily exceeding this warming level will result in additional severe impacts, some of which will be irreversible. Risks for society will increase, including to infrastructure and low-lying coastal settlements.

The Summary for Policymakers of the IPCC Working Group II report,  Climate Change 2022: Impacts, Adaptation and Vulnerability was approved on Sunday, February 27 2022, by 195 member governments of the IPCC, through a virtual approval session that was held over two weeks starting on February 14.

Urgent action required to deal with increasing risks

Increased heatwaves, droughts and floods are already exceeding plants’ and animals’ tolerance thresholds, driving mass mortalities in species such as trees and corals. These weather extremes are occurring simultaneously, causing cascading impacts that are increasingly difficult to manage. They have exposed millions of people to acute food and water insecurity, especially in Africa, Asia, Central and South America, on Small Islands and in the Arctic.

To avoid mounting loss of life, biodiversity and infrastructure, ambitious, accelerated action is required to adapt to climate change, at the same time as making rapid, deep cuts in greenhouse gas emissions. So far, progress on adaptation is uneven and there are increasing gaps between action taken and what is needed to deal with the increasing risks, the new report finds. These gaps are largest among lower-income populations. 

The Working Group II report is the second instalment of the IPCC’s Sixth Assessment Report (AR6), which will be completed this year.

“This report recognizes the interdependence of climate, biodiversity and people and integrates natural, social and economic sciences more strongly than earlier IPCC assessments,” said Hoesung Lee. “It emphasizes the urgency of immediate and more ambitious action to address climate risks. Half measures are no longer an option.”

Safeguarding and strengthening nature is key to securing a liveable future

There are options to adapt to a changing climate. This report provides new insights into nature’s potential not only to reduce climate risks but also to improve people’s lives.

“Healthy ecosystems are more resilient to climate change and provide life-critical services such as food and clean water”, said IPCC Working Group II Co-Chair Hans-Otto Pörtner. “By restoring degraded ecosystems and effectively and equitably conserving 30 to 50 per cent of Earth’s land, freshwater and ocean habitats, society can benefit from nature’s capacity to absorb and store carbon, and we can accelerate progress towards sustainable development, but adequate finance and political support are essential.”

Scientists point out that climate change interacts with global trends such as unsustainable use of natural resources, growing urbanization, social inequalities, losses and damages from extreme events and a pandemic, jeopardizing future development.

“Our assessment clearly shows that tackling all these different challenges involves everyone – governments, the private sector, civil society – working together to prioritize risk reduction, as well as equity and justice, in decision-making and investment,” said IPCC Working Group II Co-Chair Debra Roberts.

“In this way, different interests, values and world views can be reconciled. By bringing together scientific and technological know-how as well as Indigenous and local knowledge, solutions will be more effective. Failure to achieve climate resilient and sustainable development will result in a sub-optimal future for people and nature.”

Cities: Hotspots of impacts and risks, but also a crucial part of the solution

This report provides a detailed assessment of climate change impacts, risks and adaptation in cities, where more than half the world’s population lives. People’s health, lives and livelihoods, as well as property and critical infrastructure, including energy and transportation systems, are being increasingly adversely affected by hazards from heatwaves, storms, drought and flooding as well as slow-onset changes, including sea level rise.

“Together, growing urbanization and climate change create complex risks, especially for those cities that already experience poorly planned urban growth, high levels of poverty and unemployment, and a lack of basic services,” Debra Roberts said.

“But cities also provide opportunities for climate action – green buildings, reliable supplies of clean water and renewable energy, and sustainable transport systems that connect urban and rural areas can all lead to a more inclusive, fairer society.”

There is increasing evidence of adaptation that has caused unintended consequences, for example destroying nature, putting peoples’ lives at risk or increasing greenhouse gas emissions. This can be avoided by involving everyone in planning, attention to equity and justice, and drawing on Indigenous and local knowledge.

A narrowing window for action

Climate change is a global challenge that requires local solutions and that’s why the Working Group II contribution to the IPCC’s Sixth Assessment Report (AR6) provides extensive regional information to enable Climate Resilient Development.

The report clearly states Climate Resilient Development is already challenging at current warming levels. It will become more limited if global warming exceeds 1.5°C (2.7°F). In some regions it will be impossible if global warming exceeds 2°C (3.6°F). This key finding underlines the urgency for climate action, focusing on equity and justice. Adequate funding, technology transfer, political commitment and partnership lead to more effective climate change adaptation and emissions reductions.

“The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future,” said Hans-Otto Pörtner.

For more information, please contact:

IPCC Press Office, Email: [email protected]   IPCC Working Group II:  Sina Löschke,  Komila Nabiyeva: [email protected]

Notes for Editors

Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

The Working Group II report examines the impacts of climate change on nature and people around the globe. It explores future impacts at different levels of warming and the resulting risks and offers options to strengthen nature’s and society’s resilience to ongoing climate change, to fight hunger, poverty, and inequality and keep Earth a place worth living on – for current as well as for future generations. 

Working Group II introduces several new components in its latest report: One is a special section on climate change impacts, risks and options to act for cities and settlements by the sea, tropical forests, mountains, biodiversity hotspots, dryland and deserts, the Mediterranean as well as the polar regions. Another is an atlas that will present data and findings on observed and projected climate change impacts and risks from global to regional scales, thus offering even more insights for decision makers.

The Summary for Policymakers of the Working Group II contribution to the Sixth Assessment Report (AR6) as well as additional materials and information are available at https://www.ipcc.ch/report/ar6/wg2/

Note : Originally scheduled for release in September 2021, the report was delayed for several months by the COVID-19 pandemic, as work in the scientific community including the IPCC shifted online. This is the second time that the IPCC has conducted a virtual approval session for one of its reports.

AR6 Working Group II in numbers

270 authors from 67 countries

• 47 – coordinating authors
• 184 – lead authors
• 39 – review editors
• 675 – contributing authors

Over 34,000 cited references

A total of 62,418 expert and government review comments

(First Order Draft 16,348; Second Order Draft 40,293; Final Government Distribution: 5,777)

More information about the Sixth Assessment Report can be found  here .

Additional media resources

Assets available after the embargo is lifted on Media Essentials website .

Press conference recording, collection of sound bites from WGII authors, link to presentation slides, B-roll of approval session, link to launch Trello board including press release and video trailer in UN languages, a social media pack.

The website includes  outreach materials  such as videos about the IPCC and video recordings from  outreach events  conducted as webinars or live-streamed events.

Most videos published by the IPCC can be found on our  YouTube  channel. Credit for artwork

About the IPCC

The Intergovernmental Panel on Climate Change (IPCC) is the UN body for assessing the science related to climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide political leaders with periodic scientific assessments concerning climate change, its implications and risks, as well as to put forward adaptation and mitigation strategies. In the same year the UN General Assembly endorsed the action by the WMO and UNEP in jointly establishing the IPCC. It has 195 member states.

Thousands of people from all over the world contribute to the work of the IPCC. For the assessment reports, IPCC scientists volunteer their time to assess the thousands of scientific papers published each year to provide a comprehensive summary of what is known about the drivers of climate change, its impacts and future risks, and how adaptation and mitigation can reduce those risks.

The IPCC has three working groups:  Working Group I , dealing with the physical science basis of climate change;  Working Group II , dealing with impacts, adaptation and vulnerability; and  Working Group III , dealing with the mitigation of climate change. It also has a  Task Force on National Greenhouse Gas Inventories  that develops methodologies for measuring emissions and removals. As part of the IPCC, a Task Group on Data Support for Climate Change Assessments (TG-Data) provides guidance to the Data Distribution Centre (DDC) on curation, traceability, stability, availability and transparency of data and scenarios related to the reports of the IPCC.

IPCC assessments provide governments, at all levels, with scientific information that they can use to develop climate policies. IPCC assessments are a key input into the international negotiations to tackle climate change. IPCC reports are drafted and reviewed in several stages, thus guaranteeing objectivity and transparency. An IPCC assessment report consists of the contributions of the three working groups and a Synthesis Report. The Synthesis Report integrates the findings of the three working group reports and of any special reports prepared in that assessment cycle.

About the Sixth Assessment Cycle

At its 41st Session in February 2015, the IPCC decided to produce a Sixth Assessment Report (AR6). At its 42nd Session in October 2015 it elected a new Bureau that would oversee the work on this report and the Special Reports to be produced in the assessment cycle.

Global Warming of 1.5°C , an IPCC special report on the impacts of global warming of 1.5 degrees Celsius above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty  was launched in October 2018.

Climate Change and Land , an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems  was launched in August 2019, and the  Special Report on the Ocean and Cryosphere in a Changing Climate  was released in September 2019.

In May 2019 the IPCC released the  2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories , an update to the methodology used by governments to estimate their greenhouse gas emissions and removals.

In August 2021 the IPCC released the Working Group I contribution to the AR6, Climate Change 2021, the Physical Science Basis

The Working Group III contribution to the AR6 is scheduled for early April 2022.

The Synthesis Report of the Sixth Assessment Report will be completed in the second half of 2022.

For more information go to  www.ipcc.ch

Related Content

Remarks by the ipcc chair during the press conference to present the working group ii contribution to the sixth assessment report.

Monday, 28 February 2022 Distinguished representatives of the media, WMO Secretary-General Petteri, UNEP Executive Director Andersen, We have just heard …

February 2022

Fifty-fifth session of the ipcc (ipcc-55) and twelfth session of working group ii (wgii-12), february 14, 2022, working group report, ar6 climate change 2022: impacts, adaptation and vulnerability.

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Why it’s important to learn about climate change

What is climate change?

Climate change primarily refers to long-term shifts in temperatures and weather patterns. Although some shifts in climate are natural, human activities—such as the burning of fossil fuels and deforestation—are significant drivers of climate change. Energy, industry, transportation, landfills, and agriculture all contribute to greenhouse gas emissions (including carbon dioxide and methane) that trap the sun’s heat in the atmosphere and contribute to global warming—which threatens human, economic, and environmental well-being. Some examples of the consequences of climate change include intense droughts, forest fires, sea level rise, flooding, melting polar ice caps, catastrophic weather events, and a decline in biodiversity.

What a Certificate in Climate Change prepares you to do

When you commit to studying climate change, you gain the opportunity to develop the skills and policy insights that will allow you to make a positive impact on the environment and address the pressing impact of climate change. In the 4-course Certificate in Climate Change at Penn LPS Online, you’ll obtain an understanding of the Earth’s climate system and the ways it has changed over time. Through the lens of oceanic and atmospheric sciences, you’ll learn about the natural and human activities that drive climate change and develop the rhetorical ability to effectively communicate your understanding with a diverse audience.

Read on to discover more about the skills and knowledge you will obtain in the Certificate in Climate Change at Penn LPS Online.

Learn atmospheric and ocean dynamics to understand fundamental climate processes and changes

In the Certificate in Climate Change at Penn LPS Online, you’ll have a chance to deepen your insights into methods of scientific inquiry in the field. CLCH 1600: Oceanography provides an overview of marine geology, physical oceanography, and marine chemistry. This course explores topics including marine provinces, sediments, tides, renewable ocean energy, how plate tectonics shape and disrupt the ocean, and the relation between ocean circulation and climate change.

In CLCH 2200: Atmospheric Science you learn the fundamentals of how air moves, gaining insight into weather and climate change prediction and their impact on society. Primary course topics also include atmospheric composition, living organisms, ecosystems, and environmentally important issues such as greenhouse gases, acid rain, urban smog, and air toxics.

Analyze natural disasters and environmental threats both globally and regionally

Deforestation, wildfires, lead in water, the prevalence of plastics in the ocean, and other progressively more destructive natural disasters have been top-of-mind in recent years. In CLCH 3100: Global Environmental Issues , you will explore the underlying causes and potential solutions to eight such critical environmental concerns.

Through case studies taken from around the planet—including forest fires in the Amazon, the Indonesian mud flow disaster, changes in rainfall patterns, and the return of wolves to Yellowstone—you’ll become familiarized with current knowledge, debate, human impacts, economic consequences, policies, and potential resolutions for these issues. And you’ll have a chance to take a deep dive into one major environmental problem through a semester-long group project that culminates in a final paper.

Understand the history and gradations of climate change

In the Certificate in Climate Change at Penn LPS Online, you’ll also explore the mechanisms that drive climate change and learn how to use natural environmental change as a benchmark to assess human impacts, recent climate change, and potential future changes. CLCH 2300: Climate Change looks into the cryosphere (frozen parts of the world) and builds upon previous coursework to help you gain a deeper understanding of the science behind the Earth’s climate change. As you explore historical climate, you’ll learn how scientists know what it was like in the past and how and why we believe certain changes have occurred.

You will also examine current evidence for climate change such as rising sea levels, loss of glacier mass, and deviations in weather systems—and examine potential environmental impacts—to help you critique different climate models and explore climate policy in the United States and around the world.

Hone communication skills to share understanding of climate change and its implications more effectively

It’s clear that understanding both the science and policy implications of climate change is important. But it’s also critical that you be able to communicate this knowledge clearly and successfully to the broader public who may not have a scientific background. That’s where CLCH 3000: Communicating Science comes in. This course will inform you of strategies to refine your rhetorical skills and help you craft messages that relate research concepts and data to effectively engage different audiences and genres.

One such topic that you may learn how to speak about is disaster management, which refers to organized attempts to prepare for and recover from natural, technological, and terrorist hazards. In CLCH 2100:  Introduction to Disaster Management , you’ll gain an overview of the theory, principles, and operations of disaster mitigation, preparedness, response, and recovery at the federal, state, local, and nongovernmental level. You’ll also investigate the social, political, and economic consequences of these disasters.

Why is it important to learn about climate change?

It is vital to learn about climate change to stay informed on what it is, what the ramifications are, and how we can mitigate it—such as reducing the reliance on fossil fuels like coal and oil, slowing deforestation, and adopting sustainable agricultural practices. According to NASA , the consequences of exceeding a global average temperature increase of two degrees could have a devastating impact: 61 million more humans would be exposed to severe drought, up to 270 million more people would experience water shortages, the prevalence of deadly heat waves and extreme weather events would substantially increase, and almost 100% of coral reefs would die.

Climate change endangers animals. Sadly, rising global temperatures, changing weather patterns, and human development can all have an immensely destructive impact on wildlife. The increase in temperature affects animals’ food sources, vegetation, and access to water, which can cause critical losses of habitat for animals such as African elephants, giant pandas, monarch butterflies, sea turtles, tigers, polar bears, and dolphins.

The sharp increase in climate and weather-related natural disasters such as wildfires, droughts, and hurricanes have also caused disastrous losses of habitat and lives of animals. For example, the 2019-20 bushfires in Australia are estimated to have killed or displaced three billion kangaroos, koalas, and other wildlife.

With changes in ecosystems also comes an uptick in human-wildlife conflict as people and animals, such as jaguars, branch out in search of resources and end up sharing more crowded spaces. Ultimately, all of these issues can lead to extinction if not effectively addressed. For instance, the North Atlantic whale is currently struggling to survive due to the effects of rising ocean temperatures and increasing conflicts with anglers and their nets and vessels.

Climate change threatens important ecosystems. Climate change also has an increasingly ruinous impact on important ecosystems and biomes, including rainforests, coral reefs, and polar ice caps. In the Amazon, the 1.4 billion acres of dense forest represent half of the world’s remaining rainforest and 1 in 10 of all the known species on Earth. Over 1/3 of this precious habitat is threatened not only by climate change, but by deforestation, which in turn fuels the release of additional greenhouse gases.

The Coral Triangle contains nearly 600 different species of reef-building coral, six of the world’s seven marine turtle species, and over 2,000 species of reef fish. Warmer air and ocean temperatures are also causing coral bleaching and increased carbon dioxide in the atmosphere is resulting in ocean acidification, both of which are threatening this vital marine area.

The Earth's polar regions are home to diverse landscapes containing everything from polar ice caps and tundra to the sea, which support endangered wildlife such as the polar bear. Unfortunately, according to NASA, Antarctica is losing ice mass at an average of 150 billion tons per year and Greenland is losing 280 billion tons per year, contributing to rising sea levels and loss of habitat for the animals that populate these areas.

Climate change damages human health and infrastructure. The reality is that if not mediated, climate change has the potential to hurt natural ecosystems and infrastructure, increase the frequency of natural disasters, and pose significant health risks through food shortages and increased temperatures and pollution. For example, the destruction of coral reefs not only impacts the marine ecosystem, it also affects food supplies in coastal areas.

According to the  U.S. Global Change Research Program , the consequences of unchecked climate change include:

• Increasing challenges to human health and safety, quality of life, and economic growth
• Rising temperatures, drought, flooding, and wildfires will increasingly disrupt agricultural productivity in the US
• The transmission of disease through insects, pests, food, and water that will increasingly threaten peoples’ health
• Challenges to livestock health and crop declines that will threaten rural livelihoods, food security, and price stability
• Chronic high-tide flooding in coastal communities that will lead to serious financial impacts for homeowners and businesses
• Stresses to aging infrastructure from heavy rain, flooding, extreme heat, and other events that will degrade performance with the potential for threats to national security, essential services, and human health

Climate change will affect future generations. The bottom line is that no matter who you are or where you live, you cannot escape the effects of climate change. Global warming, air pollution, acidification of the ocean, destructive weather, and human activities will also have an increasingly harmful impact on future generations. However, it is possible to educate others on the dangers of climate change—including what we as individuals can do to mitigate it—and to champion businesses, political leaders, and environmental groups who are willing to act by supporting environmental policies that make a real difference. By promoting awareness, encouraging sustainable practices, and fostering resilience in the face of climate challenges, we can pave the way for a more sustainable and secure future for all.

Learn more about climate change, today

The Certificate in Climate Change at Penn LPS Online arms you with the knowledge to understand Earth’s climate system and the skills to more effectively communicate the consequences of the changing environment to businesses, communities, and the planet at large. Being able to comprehend, prepare, and mitigate the results of climate change is relevant to many fields including environmental research and science, land management, state and local community planning, government policymaking, and business in general. As an added bonus, the Ivy League online courses in this certificate program are scheduled to provide the flexibility to enhance your climate change knowledge as you move forward in your career.

Ready to get started? If you haven’t yet done so,  fill out an enrollment form  to take the first step in your Ivy League education at Penn LPS Online. Or  view our  course guide  to see the full list of offerings available.

Works consulted

https://www.mooc.org/blog/why-is-it-important-to-study-climate-change https://www.wwf.org.uk/updates/10-reasons-why-climate-change-important https://www.un.org/en/climatechange/what-is-climate-change https://www.worldwildlife.org/threats/effects-of-climate-change https://www.ifaw.org/journal/impact-climate-change-animals

• Security Council

Climate Change ‘Biggest Threat Modern Humans Have Ever Faced’, World-Renowned Naturalist Tells Security Council, Calls for Greater Global Cooperation

Climate change is a “crisis multiplier” that has profound implications for international peace and stability, Secretary-General António Guterres told the Security Council today, amid calls for deep partnerships within and beyond the United Nations system to blunt its acute effects on food security, natural resources and migration patterns fuelling tensions across countries and regions.

Throughout the morning, the Council’s high-level open debate on climate and security heard from a range of influential voices, including naturalist David Attenborough, who called climate change “the biggest threat to security that modern humans have ever faced”.  In video remarks telecast at the outset, he warned that concentrations of carbon dioxide currently in the atmosphere have not been equalled for millions of years.

“If we continue on our current path, we will face the collapse of everything that gives us our security,” he said:  food production, access to fresh water, habitable ambient temperature and ocean food chains.  The poorest — those with the least security — are certain to suffer.  “Our duty right now is surely to do all we can to help those in the most immediate danger.”

While the world will never return to the stable climate that gave birth to civilization, he said that, if Governments attending the twenty-sixth Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) in November recognize climate change as a global security threat, “we may yet act proportionately — and in time”.

Climate change can only be dealt with by unparalleled levels of global cooperation, he said.  It will compel countries to question economic models, invent new industries and recognize the moral responsibility that wealthy nations have to the rest of the world, placing a value on nature that “goes far beyond money”.  He challenged the international community to finally create a stable, healthy world where resources are equally shared and where — for the first time in history — people “come to know what it feels like to be secure”.

Mr. Guterres echoed those calls, describing the climate emergency as “the defining issue of our time”.  Noting that the last decade was the hottest in human history, he said wildfires, cyclones, floods and droughts are now the new normal.  “These shocks not only damage the environment on which we depend, they also weaken our political, economic and social systems,” he said.

Indeed, where climate change dries up rivers, reduces harvests, destroys critical infrastructure and displaces communities, it exacerbates the risks of conflict, he said.  A study by the Stockholm International Peace Research Institute found that 8 of the 10 countries hosting the largest multilateral peace operations in 2018 were in areas highly exposed to climate change.

The impact is greatest where fragility and conflict have weakened coping mechanisms, he said, where people depend on natural capital for their livelihoods and where women — who bear the greatest burden of the climate emergency — do not enjoy equal rights.  He highlighted examples in Afghanistan, where reduced harvests have pushed people into poverty, leaving them susceptible to recruitment by armed groups, and across West Africa and the Sahel, where changes in grazing patterns have fostered conflict between pastoralists and farmers.  In some Pacific small island nations, entire communities have been forced to relocate.

“The forced movement of larger numbers of people around the world will clearly increase the potential for conflict and insecurity,” he observed.  He called for greater efforts to address climate‑related security risks, starting with a focus on prevention, and creating a global coalition committed to achieving net-zero emissions by mid-century.  The United Nations is asking companies, cities and financial institutions to prepare credible decarbonization plans.

In addition, immediate actions are needed to protect countries from increasingly frequent and severe climate effects.  He urged donors and multilateral and national development banks to increase the share of adaptation and resilience finance to at least 50 per cent of their climate finance support.  Developed countries, too, must keep their pledge to channel $100 billion annually to the global South.  “They have already missed the deadline of 2020,” he acknowledged.

Above all, he called for embracing a concept of security that places people at its centre, stressing that COVID-19 has laid bare the devastation that non‑traditional security threats can cause on a global scale.  In all such efforts, it will be essential to build on the strengths of the Security Council, Peacebuilding Commission, international financial institutions, regional organizations, civil society, the private sector, academia and others.

Issuing a call to action, Nisreen Elsaim, Chair of the Youth Organization on Climate Change and the United Nations Youth Advisory Group, said young people around the globe are watching the Security Council as it grapples with climate change.  Each of the organ’s four meetings on the issue — in 2007, 2011, 2018 and 2019 — have referenced serious climate-related security risks in Somalia, Darfur, West Africa and the Sahel, Mali and the Lake Chad Basin.  “Science has forecasted many more countries will join this list if we did not take the right measures now, and if we did not start adaptation specially in Africa,” she said, adding that, in her country, “we are living in continuous insecurity due to many factors that put Sudan on the top of the list when it comes to climate vulnerability”.

She recalled that, in a 2018 Council resolution on Sudan, members recognized the adverse effects of climate change, ecological changes and natural hazards on the situation in Darfur, focusing specifically on drought, desertification, land degradation and food insecurity.  “Human survival, in a situation of resources degradation, hunger, poverty and uncontrolled climate migration, will make conflict an inevitable result,” she said.  Moreover, climate-related emergencies cause major disruptions in access to health, life-saving sexual and reproductive health services, and result in loss of livelihoods and drive displacement and migration.  They also increase the risk of gender-based violence and harmful practices and force young people to flee in search of a decent life.

Welcoming the Council’s recent deployment of a new special political mission, the United Nations Integrated Transition Assistance Mission in the Sudan (UNITAMS), she said it has a historic opportunity to speak to the root causes of the conflict.  Climate change and youth participation is mentioned twice in the Mission’s mandate, and climate change challenges are included in the 2020 Juba Peace Agreement.  Emphasizing that young people must be part of the solution, she declared:  “We are the present, we have the future, let’s not repeat previous generations’ lapse.”

In the ensuing dialogue, Heads of State and Government, along with ministers and other senior officials described national actions to attenuate the negative impact of climate change and offered their views on the related security risks.  Some pressed the Council to broaden its thinking about non-traditional security threats.  Several — including leaders from Kenya and Niger — stressed that the link between climate and conflict could not be more evident, while others explored the ability of Governments to meet people’s basic needs, and still others cast doubt on the assertion that the relationship between climate and conflict is causal, instead pointing to political and economic factors that are known to drive tensions.

Boris Johnson, Prime Minister of the United Kingdom and Council President for February, speaking in his national capacity, said the Council, while imperfect, has been willing to lead the way in confronting threats to international security.  “That is exactly what climate change represents,” he said, acknowledging that, while there are some who disagree, these cynics “could not be more wrong”.  While the causes of climate change may not sit within the Council’s traditional purview, its effects most certainly do.  He asked delegates to consider the young man forced onto the road when his once‑fertile home becomes a desert — one of the 16 million people displaced by weather-related disasters each year — who becomes easy prey for violent extremists, or the girl who drops out of school because her daily search for water takes her away from her family — and into the sights of the human traffickers.

“If such scenes were triggered by the actions of some despotic warlord or internecine conflict, few would question this Council’s right to act or its duty to do so,” he assured.  “This is not a subject from which we should shy away.”  The world must move from 51 billion metric tons of greenhouse‑gas emissions each year to net zero, so that the increase in global temperatures remains within manageable levels.  For its part, the United Kingdom Parliament passed a law committing to net zero by 2050, he said, drawing attention to his pledge that the nation would slash emissions by 68 per cent by 2030.  He urged the Council to act, “because climate change is a geopolitical issue every bit as much as an environmental one”, stressing that, if it is to succeed in maintaining peace and security worldwide, it must galvanize and support the United Nations family of agencies into a swift and effective response.

Kaïs Saïed, President of Tunisia , agreed with Ms. Elsaim that the world must listen to youth on climate change.  More broadly, humans — and not money — must be placed at the centre of the issue.  Voicing support for the Secretary-General’s 2021 priorities, especially his efforts to galvanize Member States to confront the multiple impacts of climate change, he described it as ironic that humans are, at the same time, the phenomenon’s drivers and its greatest victims.  “It is no one’s right to […] to commit all of humanity to death,” he stressed, noting that Council resolution 2532 (2020) confirmed that insecurity can be driven by a multitude of factors, not just armed conflict.  One such driver is the deepening poverty and resource scarcity resulting from a changing climate, particularly in Africa.  Climate factors often prolong conflict and create conditions conducive to deprivation, exclusion, terrorism and organized crime.

Calling on the Council to adopt a new, more comprehensive approach and for sufficient resources for all specialized agencies related to climate change, he underlined the need for early warning systems and better prevention strategies.  Noting that the COVID-19 pandemic and other recent crises have once again revealed the need for States to strengthen their solidarity, he emphasized the need for prompt action while stressing that the burden borne by States must be differentiated based on their degree of responsibility for causing the crisis.  Moreover, mitigation cannot be at the expense of developing countries, he said.

Uhuru Kenyatta, President of Kenya , said that new approaches to investment by the public and private sector need to reach the countries and regions worst hit by climate change.  Persistent droughts, constant sea‑level rise and increasingly frequent extreme weather patterns are reversing economic growth and development gains achieved over decades.  The result is increased fragility to instability and armed conflict that then come to the attention of this Security Council.  The implementation of the Council’s mandate to maintain global peace and security will only get more difficult with time if climate change remains on its present course.  Rather than wait for a future tipping point, we must redouble the efforts to direct all the resources and multilateral frameworks of our rules-based international order to mitigate the effects of climate change.  While the bulk of this work is happening outside the Council, no body with such a strong mandate should step aside from this challenge.

The climate-security nexus is already impacting Africa.  “Listen to us Africans when we tell you that the link is clear, its impact tangible and the need for solutions urgent,” he said.  Making recommendations, he said that the Council must do more when crafting mandates for conflict resolution and post-conflict resolution to ensure they dovetail with the efforts to deploy climate change mitigation and adaptation measures.  In this regard, he applauded Council resolutions 2349 (2017) and 2502 (2019), respectively on Lake Chad and the Democratic Republic of the Congo, that have integrated measures to address the impact of climate change.  The 15-member organ can also act strongly against illicit financial outflows, illicit resource exploitation, terrorism financing and money‑laundering in the most fragile regions in Africa.  Doing so immediately boosts the resources available to Governments to undertake climate change mitigation and offer the public services and goods needed to consolidate and protect peace.

Brigi Rafini, Prime Minister of Niger , agreed that the impact of climate change on peace and security is increasingly evident, stressing that water scarcity exacerbated by climate change could see gross domestic product (GDP) in the Sahel fall by 6 per cent and hunger increase 20 per cent by 2050.  Climate change has increased competition for diminished land and water resources, ramping up tensions between livestock owners and others.  He underscored the collective responsibility to tackle this existential challenge, stressing that “climate change and land degradation are no longer purely environmental matters”.  Rather, they are part of a broader view that links environmental goals with those for economic and social development, and the pursuit of international peace and stability.

“We need to consider climate change as a threat to peace and security,” he said, urging the Council to shore up its understanding of impact on security and to systematically consider climate change in its resolutions pertaining to specific country and regional contexts.  In such efforts, it should rely on the advisory role of the Peacebuilding Commission, and the Informal Expert Group on Climate and Security, co-chaired by Niger and Ireland.  The appointment of a Special Envoy of the Secretary-General for Climate and Security likewise will raise the profile of this dimension within the Council’s work.

Nguyễn Xuân Phúc, Prime Minister of Viet Nam , said the Earth’s recent calamities have placed great burdens on the political and socioeconomic life of many countries, causing unemployment and poverty, creating instability and exacerbating current conflicts.  Against that backdrop, the Council should galvanize the international community’s collective efforts with an approach that is balanced between traditional and non-traditional security challenges.  That includes addressing the root causes of conflicts such as poverty, inequality, power politics and unilateral interference and coercion.

Calling for strict adherence to the Charter of the United Nations and international law, he said the 2030 Agenda for Sustainable Development, the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement on climate change must guide the way, and greater resources are needed to support developing countries, least developed countries, small island developing States and landlocked countries.  The Council should also enhance its early warning capacity, bolster its mediation and conflict prevention roles, work more closely with regional organizations and fully respect States’ sovereignty and national ownership.  Noting that Viet Nam is among the six countries most severely affected by climate change, he outlined various national efforts to address the challenge while requesting more international assistance.

Erna Solberg, Prime Minister of Norway , emphasized that climate change is redefining the global security landscape.  “We must rethink and adapt the Council’s approaches to peacebuilding and sustaining peace in three ways,” she said.  First, the Council needs better information on climate-related security risks.  International research networks and the informal expert group will be important in that regard.  Norway has helped establish a Nordic-Baltic expert network.  Second, the Council should discuss climate risks in specific country contexts, based on country reporting and briefings.  The United Nations must be at the forefront of preventive diplomacy.  To achieve sustainable solutions, peace diplomacy must be climate-sensitive, and climate action must be conflict‑sensitive.  Third, it is imperative to strengthen partnerships within and beyond the United Nations system, including with affected States and regional organizations.  The active participation of diverse groups, including women and youth, is also vital.

The national security communities in many countries have understood the security risks posed by climate change, she continued.  While climate change can lead to hard security challenges, there are no hard security solutions.  The first line of defence is ambitious climate action.  It must begin with the full implementation of the Paris Agreement and 2030 Agenda.  Climate action depends on multilateral cooperation.  By shouldering a common responsibility to counter climate change, the Council will be better prepared to maintain international peace and stability.

Ralph E. Gonsalves, Prime Minister and Minister for Foreign Affairs of Saint Vincent and the Grenadines , emphasizing that the Council has a responsibility to address the consequences of climate change, said a failure to do so would be, in part, “an abdication of our duty”.  It is time for the organ to seriously consider drafting a resolution on the matter and to map out a coherent approach, aiming for a working consensus.  Affirming UNFCCC’s role as the primary body for dealing with climate change and the Paris Agreement as a major part of the rules-based international system, he said the Council should play its role without encroaching on the work of UNFCCC’s inclusive decision-making body.  It should also engage with the Peacebuilding Commission and the General Assembly on climate and security risks that touch on issues of humanitarian support, sustainable development, health pandemics, peace and security.

Stressing that the first step to prevent or contain climate-security risks is for the major, and historical, emitters to fulfil — and indeed exceed — the commitments made in the Paris Agreement, he underlined the principle of common but differentiated responsibility.  Climate change is an existential threat that disproportionately affects the most vulnerable, especially small island developing States such as Saint Vincent and the Grenadines.  “It has become distressingly commonplace for an entire year’s [gross domestic product] to be washed away by a hurricane overnight, even as we are hindered by a lack of a sufficient inclusion, on favourable terms, into the global financial architecture,” he said.  Citing the many natural hazards in Haiti, in particular, he also drew attention to the Sahel region and the battle for dwindling resources.  However, no country is immune to such human-made challenges and all must stand in solidarity, with the Council paying close attention to climate change as it crafts its mandates, he said.

Kaja Kallas, Prime Minister of Estonia , said 7 of the 10 countries most vulnerable and least prepared to deal with climate change host a United Nations peacekeeping operation or a special political mission — a fact the Council cannot ignore.  She expressed support for the statement to be delivered by Germany’s Foreign Minister on behalf of like-minded countries pointing the way forward for the Council, stressing that “we need to acknowledge that the climate emergency can pose a danger to peace — and we must make it a part of our security policy planning and discussions here”.  She pressed the Council to “do more” to fully

aspects of its work, noting that the Secretary-General must receive a mandate to collect data and coordinate policy to this aim.

Among other efforts, she said that Estonia cooperates with small island States and least developed countries in green technology solutions and know-how transfer.  The Government also recently launched the Data for the Environment Alliance, a coalition of State and non-State actors that will support the United Nations Environment Programme (UNEP) in developing a global environmental data strategy by 2025.

Simon Coveney, Minister for Foreign Affairs and Defence of Ireland , said that climate change has many complex impacts, not least on international peace and security, the very business of this Council.  Climate change is already causing upheaval, affecting peace and security and the stability of societies.  Pointing out that the relationship between climate and security works in complex ways, he said political instability undermines efforts to build climate resilience, and the impact of climactic shocks is compounded when institutions are strained.  Ireland is proud to join the Weathering Risk Project to help guide action at the Security Council and beyond, and is keen to understand better not just how climate change contributes to insecurity but how climate action can build peace.  Ireland chairs the Informal Expert Group of Member States on this topic, together with Niger, also partnering with Nauru and Germany, as Chairs of the Group of Friends on Climate and Security.

Ireland’s core message today is that the inclusion of climate in Council discussions and actions will strengthen conflict prevention and support peacebuilding efforts.  Stressing the need to ensure the full, equal and meaningful participation of women and youth in decision-making processes related to climate issues and the management of natural resources, he declared:  “But, in listening to and understanding the concerns and insights of future generations, we cannot abrogate our responsibility to provide leadership today”.

Marcelo Ebrard Casaubón, Minister for Foreign Affairs of Mexico , said the COVID-19 pandemic has revealed that international peace and security can no longer be viewed through a single lens, but must also consider multiple drivers of insecurity.  Food insecurity, water scarcity and droughts — all exacerbated by climate change — have reached severe levels in several regions of the world.  Pledging Mexico’s support to the next Conference of Parties to the UNFCCC in Glasgow, later in 2021, he said climate change requires a comprehensive global response with a focus on ecosystem preservations.  Mexico recently submitted its own national plan in that arena, which is coupled with a focus on prevention and adaptation, as well as efforts to reduce inequality and strengthen communities.  Stressing that all efforts must be taken in line with the 2030 Agenda, he welcomed the Council’s creation of an informal group to monitor the links between climate and peace and security as a timely measure.  Underlining the importance of ensuring sustainable peacebuilding and protecting livelihoods, he agreed with the Secretary-General that post-pandemic recovery efforts are an opportunity to “build back better” and build more egalitarian, adaptable societies.

Emmanuel Macron, President of France , said protecting the environment has, in recent years, meant recognizing climate change as a peace and security issue.  Of the 20 countries most affected by conflict in the world, 12 are also severely impacted by climate change, he said, spotlighting the impacts of desertification, the increase in forced migration and agricultural challenges — all of which have resulted in such fallout as the advent of climate refugees and growing conflicts over land and water.  Endorsing the initiative to address such matters under the auspices of the Council, he echoed calls for the appointment of a United Nations Special Envoy for Climate Security, as well as for an annual Secretary-General’s report with relevant recommendations.

Recognizing that the effects of climate change are unfairly distributed worldwide, he recalled his recent call for France’s contribution to the Green Climate Fund to be increased to one third of its total.  France strongly supports the creation of a “Great Green Wall” in Africa, which aims to restore 250 million hectares of land for agriculture, create 10 million green new jobs and sequester carbon.  He also pledged France’s commitment to accelerating the preservation of biodiversity, while calling for strengthened dialogue between the African Union and the United Nations on climate and security.  Turning to the Pacific, where many nations are struggling to implement mitigation measures, he called for additional international support and an easing of geopolitical tensions across the region.

Prakash Javadekar, Minister for Environment, Forests and Climate Change of  India , recalled the global democratic effort to take climate action in a nationally determined manner, based on the principle of common but differentiated responsibility and respective capabilities.  He cautioned the Council against building a parallel climate track where such principles are “brushed aside”.  Noting that there is no common, widely accepted methodology for assessing the links between climate change, conflict and fragility, he said fragility and climate impact are highly context‑specific.  In fragile contexts, where Governments struggle to provide basic services, emergency conditions are largely driven by political violence disrupting harvests and aid supplies, rather than by climate factors alone.  “A complete picture of climate vulnerability only emerges with an assessment of the State’s capacity to be the primary responder to interrelated environmental, social, economic and security dynamics,” he said.  While climate change does not directly cause violent conflict, its interaction with other social, political and economic factors can exacerbate conflict drivers.  He called for the building of robust governance structures at local, national and regional levels to address climate‑ and fragility-related risks, pressing donor countries to provide greater financial, technological and capacity-building assistance to help fragile States enact adaption and mitigation strategies.

John F. Kerry, Special Presidential Envoy for Climate of the United States , thanked European and other countries for their leadership on climate change during what he described as the United States “inexcusable absence” from the debate over the past four years.  Though climate change is indeed an existential threat, the world has yet to adequately respond to it.  Noting that the question of climate change is no longer one for debate, he declared:  “The evidence, the science, is screaming at us.”  Many of the world’s regions most impacted by climate change are also projected to become future conflict hotspots.  Therefore, the issue must feature in all of the Council’s work and reporting.  Emphasizing that President Joseph R. Biden understands that “we do not have a moment to waste”, he cited his new coordinated, whole-of-Government approach which aims to elevate the issue and put the United States on the path to sustainability that can never be reversed by any future President or demagogue.

Addressing climate change will require every country to step up and boost their level of ambition, he said, noting that the world’s largest carbon emitters bear the greatest responsibility.  First and foremost will be the need to reduce the use of coal globally.  “Inaction comes with a far higher price tag than action,” he said, stressing that, not since the industrial revolution has there been such potential to build back better in every part of the globe.  Just by doing nothing, humanity will march forward in what is tantamount to a mutual suicide pact, he warned, spotlighting the importance of the climate summit to be hosted by President Biden in the coming weeks, as well as the Conference of Parties to the UNFCCC to be held in Glasgow later in 2021.  The United States will also work with like-minded countries in the Council, he said, urging Member States to begin treating climate change as the security crisis that it is.

Xie Zhenhua, Special Envoy for Climate Change of China , said that, even as global climate governance enters a new and crucial phase, the spread of COVID-19 poses serious threats to the global response.  Given the differences in historical responsibility and development levels between States, he underscored the principle of common but differentiated responsibility and urged developed nations to lead the way.  In building back after the pandemic, countries should respect nature, protect biodiversity, champion green lifestyles and “avoid old paths of giving without taking” from the Earth.  In that context, he described climate change as a development issue, urging the international community to support developing nations, least developed countries and small island developing States in implementing mitigation and adaptation measures.

“We need to stay committed to multilateralism,” he stressed, underlining the importance of UNFCCC and the Paris Agreement as the main channels for those critical discussions.  Any role to be played by the Security Council on climate change must fall under its purview, he added.  Outlining China’s commitment to fulfilling its responsibilities under the Paris Agreement, he spotlighted its recently announced plan to have national CO 2 emissions peak before 2030 and to achieve carbon neutrality prior to 2060.  He also pointed out that the country’s forest cover has been rising steadily for many years, that it leads the world in green power generation and that it tops the list of clean energy patents registered.

The representative of the Russian Federation agreed that addressing climate change requires a global approach that is coordinated, targeted at reducing emissions and implementing effective adaptation measures, especially through UNFCCC.  Noting that the Council has discussed climate change on several occasions, he said the issue is often presented as a fundamental threat to stability and as a root cause of problems, particularly in Africa, with warnings about the increasing risks of conflict.  While he agreed that climate change can exacerbate conflict, he questioned whether it is the root cause of violence.  “There are serious doubts,” he said.  The connection between climate and conflict can be examined only in certain countries and regions.  Discussing it in the global context is not relevant.  “Not all conflicts are threats to international peace and security,” he explained.  In addition, considering climate as a root cause of security issues distracts from the true root causes, and thus, hinders solutions.  Political and socioeconomic factors, which have a greater influence on conflict risk, cannot be ignored, he said, pointing out that COVID-19 has exacerbated inequalities within and between countries and sparked an uptick in hunger — including in countries that were already in conflict.  He urged donors to address the problem of “green protectionism”, seen in their refusal to exchange technology that would allow others to adapt.   While discussing climate issues in the Council is seen as beneficial, the “real work” of improving coordination of international activities would be better accomplished in the General Assembly, the Economic and Social Council and UNFCC.  Conflicts — in and of themselves — reduce the ability of States to adapt to climate change, he said, explaining that the increased security risks in the Sahel are, in fact, caused by countries pursuing regime change in Libya.

Lazarus McCarthy Chakwera, President of Malawi , speaking for the least developed countries, said building resilience to mitigate the security risks associated with climate change must begin with reflections on COVID-19, as Governments have relegated many other priorities in the quest to fight the virus.  Describing the impact of the nexus between climate change and security is “indiscriminate and consequential”, he said water scarcity, desertification and cyclones all foster competition for resources, and in the process, turn people into climate refugees.  Least developed countries bear the brunt of these phenomena, despite that their emissions are 30 times lower than those of high‑income countries.  Stressing that recovery from the coronavirus must be aligned with efforts to limit global temperature rise to 1.5°C, he pressed developed countries to approach the 2021 UNFCC meeting with more ambition than in years past, as their current commitments to cut emissions remain “woefully inadequate”.  They must fulfil their pledges to provide $100 billion in climate financing annually, answer the call to earmark 50 per cent of financing in the Green Climate Fund for adaptation, especially in least developed countries, and to meaningfully transfer climate‑friendly technologies to help least developed countries accelerate their green development efforts.

Gaston Alphonso Browne, Prime Minister and Minister for Finance and Corporate Governance of Antigua and Barbuda , spoke on behalf of the Alliance of Small Island States, declaring:  “Make no mistake […] climate change’s existential threat to our own survival is not a future consideration, but a current reality.”  For the past 30 years, the Alliance has been the single most consistent advocate on climate, he said, highlighting the often-overlooked threats faced by small island developing States.  He urged the international community to simultaneously plan and operationalize a system to address inevitable loss and damage which uproot peace and security of small island developing States.  Equitable solutions are needed to systematically address difficult issues, such as climate change displacement, including the treatment of climate refugees, and loss of territory. For the past three decades, small island and low-lying States have been sounding the alarm, sending the SOS distress signal.  They are losing their territories, populations, resources and very existence due to climate change.  The Secretary-General recently stated:  “Without nature’s help, we will not thrive or even survive[…] For too long, we have been waging a senseless and suicidal war on nature.”  Sadly, small island developing States continue to be the front line for this war.  “Our appeal for the Council is to take this threat very seriously before it is too late,” he said.

Heiko Maas, Federal Minister for Foreign Affairs of Germany , speaking for the Group of Friends of Climate and Security, said those countries are united by the common belief that climate change is the fundamental challenge of our time.  The poorest and most vulnerable are suffering the most, with entire islands at risk of disappearing.  “We are putting their future, their safety and their well‑being at risk if we don’t act,” he stressed, calling for concerted efforts by the United Nations in making climate change its top priority.  Agreeing with other speakers that the issue has major implications for peace and security, he said it therefore belongs firmly on the Council’s agenda.  In July 2020, the Nauru delegation presented the organ with a plan of action, including calling for the appointment of a Special Envoy on Climate and Security; regular reporting to the Council; climate‑sensitive peacebuilding; and more cooperation with civil society, regional and national actors on climate-related security risks.  Now, it is time for the Council to adopt a strong resolution reflecting each of those points, he said.

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Causes of global warming, explained

Human activity is driving climate change, including global temperature rise.

The average temperature of the Earth is rising at nearly twice the rate it was 50 years ago. This rapid warming trend cannot be explained by natural cycles alone, scientists have concluded. The only way to explain the pattern is to include the effect of greenhouse gases (GHGs) emitted by humans.

Current levels of the greenhouse gases carbon dioxide, methane, and nitrous oxide in our atmosphere are higher than at any point over the past 800,000 years , and their ability to trap heat is changing our climate in multiple ways .

IPCC conclusions

To come to a scientific conclusion on climate change and what to do about it, the United Nations in 1988 formed a group called the Intergovernmental Panel on Climate Change , or IPCC. The IPCC meets every few years to review the latest scientific findings and write a report summarizing all that is known about global warming. Each report represents a consensus, or agreement, among hundreds of leading scientists.

One of the first things the IPCC concluded is that there are several greenhouse gases responsible for warming, and humans emit them in a variety of ways. Most come from the combustion of fossil fuels in cars, buildings, factories, and power plants. The gas responsible for the most warming is carbon dioxide, or CO2. Other contributors include methane released from landfills, natural gas and petroleum industries, and agriculture (especially from the digestive systems of grazing animals); nitrous oxide from fertilizers; gases used for refrigeration and industrial processes; and the loss of forests that would otherwise store CO2.

Gaseous abilities

Different greenhouse gases have very different heat-trapping abilities. Some of them can trap more heat than an equivalent amount of CO2. A molecule of methane doesn't hang around the atmosphere as long as a molecule of carbon dioxide will, but it is at least 84 times more potent over two decades. Nitrous oxide is 264 times more powerful than CO2.

Other gases, such as chlorofluorocarbons, or CFCs—which have been banned in much of the world because they also degrade the ozone layer—have heat-trapping potential thousands of times greater than CO2. But because their emissions are much lower than CO2 , none of these gases trap as much heat in the atmosphere as CO2 does.

When those gases that humans are adding to Earth's atmosphere trap heat, it’s called the "greenhouse effect." The gases let light through but then keep much of the heat that radiates from the surface from escaping back into space, like the glass walls of a greenhouse. The more greenhouse gases in the atmosphere, the more dramatic the effect, and the more warming that happens.

Climate change continues

Despite global efforts to address climate change, including the landmark 2015 Paris climate agreement , carbon dioxide emissions from fossil fuels continue to rise, hitting record levels in 2018 .

Many people think of global warming and climate change as synonyms, but scientists prefer to use “climate change” when describing the complex shifts now affecting our planet’s weather and climate systems. Climate change encompasses not only rising average temperatures but also extreme weather events, shifting wildlife populations and and habitats, rising seas , and a range of other impacts.

Read next: Global Warming Effects

Related Topics

• CLIMATE CHANGE
• ENVIRONMENT AND CONSERVATION
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The global warming that’s causing our climate crisis is already having dire consequences.

In just the past few decades:

• Rising temperatures have worsened extreme weather events .
• Chunks of ice in the Antarctic have broken apart .
• Wildfire seasons are months longer .
• Coral reefs have been bleached of their colors .
• Mosquitoes are expanding their territory, able to spread disease .

What’s causing this climate crisis?

It’s mainly us.

Humans are the main cause of climate change — we burn fossil fuels and chop down forests, causing average temperatures to rise worldwide. That global warming trend is increasingly disrupting our climate — the average weather over many years.

Earth has already warmed by about 1 degree Celsius, or 1.8 degrees Fahrenheit, since the 19th century, before industry started to boom.

While we experience the effects , we’re on our way toward 1.5 degrees C (2.7 F) by as early as 2030.

7 facts about climate change

Why a half-degree more is such a big deal

A warmer world — even by a half-degree Celsius — has more evaporation, leading to more water in the atmosphere. Such changing conditions put our agriculture, health, water supply and more at risk.

Picture a North Carolina cotton farm that’s been around since 1960, with global average temperatures rising by roughly half a degree since it grew its first crop.

The increased evaporation and additional moisture to the atmosphere has led to 30% more intense rain during heavy downpours in that part of the U.S.

Then a hurricane like 2018’s Florence — already strengthened by warmer oceans and higher seas — dumps this excess rainfall on the farm. The crops get more flooded and damaged than they did half a century ago.

It's how you go from half-degree of warming to economic hardship.

Are record-breaking hurricanes our new normal?

There’s still time to act

Whether it’s a shift of 1.5 degrees or 2 degrees, these warming levels aren’t magic thresholds. Every rise in warming is worse for the planet than the last.

But they're not inevitable.

It's not too late to slow the pace of climate change and avert the worst impacts of the climate crisis — as long as we act today. With your help, we can attack this challenge.

Donate now to have triple the impact in the climate fight

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Together we can create vital progress for our climate, environment and health

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• Join a powerful force of over 3 million allies.
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What Are the Causes of Climate Change?

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

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

Andrew Innerarity/California Department of Water Resources

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

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

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

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

Natural causes of climate change

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

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

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

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

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

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

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

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

Traffic on Interstate 25 in Denver

David Parsons/iStock

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

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

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

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

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

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

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

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

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

Stephanie Foden for NRDC

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

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

Matthew Busch/Bloomberg via Getty Images

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

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

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

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

River Jordan for NRDC

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

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

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

Sarah Baker

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

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

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

This NRDC.org story is available for online republication by news media outlets or nonprofits under these conditions: The writer(s) must be credited with a byline; you must note prominently that the story was originally published by NRDC.org and link to the original; the story cannot be edited (beyond simple things such as grammar); you can’t resell the story in any form or grant republishing rights to other outlets; you can’t republish our material wholesale or automatically—you need to select stories individually; you can’t republish the photos or graphics on our site without specific permission; you should drop us a note to let us know when you’ve used one of our stories.

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Explore 7 Climate Change Solutions

In this lesson, students will use a jigsaw activity to learn about some of the most effective strategies and technologies that can help head off the worst effects of global warming.

By Natalie Proulx

Lesson Overview

Earlier this summer, a report issued by the Intergovernmental Panel on Climate Change , a body of scientists convened by the United Nations, found that some devastating impacts of global warming were unavoidable. But there is still a short window to stop things from getting even worse.

This report will be central at COP26 , the international climate summit where about 20,000 heads of state, diplomats and activists are meeting in person this week to set new targets for cutting emissions from coal, oil and gas that are heating the planet.

In this lesson, you will learn about seven ways we can slow down climate change and head off some of its most catastrophic consequences while we still have time. Using a jigsaw activity , you’ll become an expert in one of these strategies or technologies and share what you learn with your classmates. Then, you will develop your own climate plan and consider ways you can make a difference based on your new knowledge.

What do you know about the ways the world can slow climate change? Start by making a list of strategies, technologies or policies that could help solve the climate crisis.

Which of your ideas do you think could have the biggest impact on climate change? Circle what you think might be the top three.

Now, test your knowledge by taking this 2017 interactive quiz:

How Much Do You Know About Solving Global Warming?

A new book presents 100 potential solutions. Can you figure out which ones are top ranked?

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Essay on Climate Change: Check Samples in 100, 250 Words

• Updated on  
• Sep 21, 2023

Writing an essay on climate change is crucial to raise awareness and advocate for action. The world is facing environmental challenges, so in a situation like this such essay topics can serve as s platform to discuss the causes, effects, and solutions to this pressing issue. They offer an opportunity to engage readers in understanding the urgency of mitigating climate change for the sake of our planet’s future.

Must Read: Essay On Environment  

Table of Contents

• 1 What Is Climate Change?
• 2 What are the Causes of Climate Change?
• 3 What are the effects of Climate Change?
• 4 How to fight climate change?
• 5 Essay On Climate Change in 100 Words
• 6 Climate Change Sample Essay 250 Words

What Is Climate Change?

Climate change is the significant variation of average weather conditions becoming, for example, warmer, wetter, or drier—over several decades or longer. It may be natural or anthropogenic. However, in recent times, it’s been in the top headlines due to escalations caused by human interference.

What are the Causes of Climate Change?

Obama at the First Session of COP21 rightly quoted “We are the first generation to feel the impact of climate change, and the last generation that can do something about it.”.Identifying the causes of climate change is the first step to take in our fight against climate change. Below stated are some of the causes of climate change:

• Greenhouse Gas Emissions: Mainly from burning fossil fuels (coal, oil, and natural gas) for energy and transportation.
• Deforestation: The cutting down of trees reduces the planet’s capacity to absorb carbon dioxide.
• Industrial Processes: Certain manufacturing activities release potent greenhouse gases.
• Agriculture: Livestock and rice cultivation emit methane, a potent greenhouse gas.

What are the effects of Climate Change?

Climate change poses a huge risk to almost all life forms on Earth. The effects of climate change are listed below:

• Global Warming: Increased temperatures due to trapped heat from greenhouse gases.
• Melting Ice and Rising Sea Levels: Ice caps and glaciers melt, causing oceans to rise.
• Extreme Weather Events: More frequent and severe hurricanes, droughts, and wildfires.
• Ocean Acidification: Oceans absorb excess CO2, leading to more acidic waters harming marine life.
• Disrupted Ecosystems: Shifting climate patterns disrupt habitats and threaten biodiversity.
• Food and Water Scarcity: Altered weather affects crop yields and strains water resources.
• Human Health Risks: Heat-related illnesses and the spread of diseases.
• Economic Impact: Damage to infrastructure and increased disaster-related costs.
• Migration and Conflict: Climate-induced displacement and resource competition.

How to fight climate change?

‘Climate change is a terrible problem, and it absolutely needs to be solved. It deserves to be a huge priority,’ says Bill Gates. The below points highlight key actions to combat climate change effectively.

• Energy Efficiency: Improve energy efficiency in all sectors.
• Protect Forests: Stop deforestation and promote reforestation.
• Sustainable Agriculture: Adopt eco-friendly farming practices.
• Advocacy: Raise awareness and advocate for climate-friendly policies.
• Innovation: Invest in green technologies and research.
• Government Policies: Enforce climate-friendly regulations and targets.
• Corporate Responsibility: Encourage sustainable business practices.
• Individual Action: Reduce personal carbon footprint and inspire others.

Essay On Climate Change in 100 Words

Climate change refers to long-term alterations in Earth’s climate patterns, primarily driven by human activities, such as burning fossil fuels and deforestation, which release greenhouse gases into the atmosphere. These gases trap heat, leading to global warming. The consequences of climate change are widespread and devastating. Rising temperatures cause polar ice caps to melt, contributing to sea level rise and threatening coastal communities. Extreme weather events, like hurricanes and wildfires, become more frequent and severe, endangering lives and livelihoods. Additionally, shifts in weather patterns can disrupt agriculture, leading to food shortages. To combat climate change, global cooperation, renewable energy adoption, and sustainable practices are crucial for a more sustainable future.

Must Read: Essay On Global Warming

Climate Change Sample Essay 250 Words

Climate change represents a pressing global challenge that demands immediate attention and concerted efforts. Human activities, primarily the burning of fossil fuels and deforestation, have significantly increased the concentration of greenhouse gases in the atmosphere. This results in a greenhouse effect, trapping heat and leading to a rise in global temperatures, commonly referred to as global warming.

The consequences of climate change are far-reaching and profound. Rising sea levels threaten coastal communities, displacing millions and endangering vital infrastructure. Extreme weather events, such as hurricanes, droughts, and wildfires, have become more frequent and severe, causing devastating economic and human losses. Disrupted ecosystems affect biodiversity and the availability of vital resources, from clean water to agricultural yields.

Moreover, climate change has serious implications for food and water security. Changing weather patterns disrupt traditional farming practices and strain freshwater resources, potentially leading to conflicts over access to essential commodities.

Addressing climate change necessitates a multifaceted approach. First, countries must reduce their greenhouse gas emissions through the transition to renewable energy sources, increased energy efficiency, and reforestation efforts. International cooperation is crucial to set emission reduction targets and hold nations accountable for meeting them.

In conclusion, climate change is a global crisis with profound and immediate consequences. Urgent action is needed to mitigate its impacts and secure a sustainable future for our planet. By reducing emissions and implementing adaptation strategies, we can protect vulnerable communities, preserve ecosystems, and ensure a livable planet for future generations. The time to act is now.

Climate change refers to long-term shifts in Earth’s climate patterns, primarily driven by human activities like burning fossil fuels and deforestation.

Five key causes of climate change include excessive greenhouse gas emissions from human activities, notably burning fossil fuels and deforestation. 

We hope this blog gave you an idea about how to write and present an essay on climate change that puts forth your opinions. The skill of writing an essay comes in handy when appearing for standardized language tests. Thinking of taking one soon? Leverage Edu provides the best online test prep for the same via Leverage Live . Register today to know more!

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The climate is changing, but not just because of humans. Here's why that matters.

The climate is changing — the thing is, it isn’t just due to humans.

Natural forces beyond human control are also gradually affecting our climate. These geophysical forces are vital to understanding global warming. Man is indeed responsible for a large portion — possibly even a majority — of global warming. But also in play are complex gravitational interactions, including changes in the Earth’s orbit, axial tilt and torque.

This fact needs to be included in the public debate. Because these gravitational shifts, occurring over millennia, can influence climate patterns and ultimately lead to noticeable variations in seasons. Interestingly, research suggests climate change can alter the tilt of the Earth, but an unrelated change in tilt can also further change the climate. It is a balance-counterbalance relationship.

Changes in the Earth’s path around the Sun, or eccentricity, involve shifts in the orbit around the Sun from a roughly circular journey to more of an elliptical one . When the Earth gradually adopts a more elliptical orbit, there are more pronounced temperatures during the summer and winter months. This alteration is exacerbated when the Earth’s axial tilt is inclined to a sharper degree than usual. As this happens, it causes the North and South Poles to be positioned more directly toward the Sun.

Haven’t you noticed the recent rise in irregular weather patterns? This is not just a man-made problem. Gradual slight variations in the Earth’s orbit around the Sun can strongly influence temperature extremes. This is important because the conversation around climate change has become so politicized, we've totally lost sight of the science — and with it, any room for bipartisanship.

Tropical storms, for example, have been forming later in what we know as hurricane season. Based on my own analysis, over the past three decades, the majority of Category 3 or stronger storms to hit the United States appear from late August to early October. Earlier in the 20th century, storms usually occurred in June, July and early August.

It doesn’t stop there. Changes in seasons can also affect other types of storms, including severe winter snowstorms and tornadoes. Recall the Storm of the Century in 1993 on the heels of Hurricane Andrew the year prior. Or what about the recent string of snowstorms (with names like Snowpocalypse, Snowmageddon and Snowzilla) dovetailing with warm-weather superstorms. Climate extremes are evident, and not just with hurricanes.

The variations in the Earth’s orbit are known as the Milankovitch cycles — after the Serbian geophysicist Milutin Milanković, who hypothesized this phenomenon in the 1920s. He discovered that variations in the Earth’s path around the Sun, axial tilt and torque could together affect our climate.

Even a slight change or orientation in the precession of the Earth’s rotating body can cause a wobbling effect shifting torque in different areas since the planet is not a perfect sphere to some people’s surprise.

Now would seem a particularly apt time to act. The 2017 Atlantic hurricane season was an intense, record-setting period . With several landfall hurricanes — Harvey, Irma, Jose and Maria — barreling their way through the Caribbean and Gulf of Mexico, devastating parts of the Leeward Islands and United States.

Still, even President Donald J. Trump has implied the whole of idea climate change may just be a hoax . Most Republicans seem to agree that it is not a serious problem.

Meanwhile, while some Democrats have tried to use the frequency and intensity of storms in the hopes of highlighting the climate change conversation, even this effort has seemed muted.

To make effective policy, it is important for politicians and activists alike to set aside their ideological differences.

There is now a real opportunity for new legislation, sound environmental legislation. But will we squander this unprecedented opportunity, punting the ball yet again? You can bet on it. Given the realities of everyday life, the extent of social beliefs, political attitudes and economic perspectives vary on a wide range of policy issues.

To make sound and effective policy, it is important for politicians and activists alike to set aside their ideological differences and return to the basics of science, in this case, the mechanics of science. After all, shouldn’t we be relying more heavily upon geoscientists and weather forecasters to provide evidence-based data and predictive modeling?

Risks to disasters are increasing. Population growth along coastlines worldwide, in addition to technological and infrastructural development, will inherently result in a concomitant increase in places prone to disasters. Modern society relies upon government for effective response to and recovery from such events.

Change is occurring and will continue to do so. As the population continues to explode and resources are consumed on a massive scale, trying to stop both is unrealistic. It is more than just being unrealistic, it is simply wasting critical time. I know, science isn’t sexy. The obsession on why storms are occurring in lieu of discussing the how is leading us down a dangerous path. A deadly path.

The heightened culture of disaster only feeds our attention on political banter and ideological semantics with no room for informed decision-making.

We get it, Mother Nature always wins. So, are we now faced with the sobering lesson that little can be done, and we should just throw in the towel? No, of course not. Though climate change is inevitable, we also need to have a healthy appreciation of the fact that climate shifts aren’t just limited to rapidly changing weather patterns.

Turning the corner into unexplored territory is always difficult. By having a broader sense of communal resiliency — social, political and economic standing — we can manage this unavoidable pendulum of climate extremes. With the recent sweeping of storms draining response efforts and budgetary resources, now is the time to set aside the theatrical shenanigans and engage in realpolitik.

Tonya T. Neaves is the director for the Centers on the Public Service at George Mason University’s Schar School of Policy and Government, where she also is a faculty member in its master of public administration program and coordinator for the Emergency Management and Homeland Security certificate.

Tonya T. Neaves is the director for the Centers on the Public Service at George Mason University’s Schar School of Policy and Government, where she also is a faculty member in its master of public administration program and coordinator for the Emergency Management and Homeland Security certificate. 

What has worked to fight climate change? Policies where someone pays for polluting, study finds

To figure out what really works when nations try to fight climate change, researchers looked at 1,500 ways countries have tried to curb heat-trapping gases

WASHINGTON -- To figure out what really works when nations try to fight climate change, researchers looked at 1,500 ways countries have tried to curb heat-trapping gases. Their answer: Not many have done the job. And success often means someone has to pay a price, whether at the pump or elsewhere.

In only 63 cases since 1998, did researchers find policies that resulted in significant cuts of carbon pollution, a new study in Thursday's journal Science found.

Moves toward phasing out fossil fuel use and gas-powered engines, for example, haven't worked by themselves, but they are more successful when combined with some kind of energy tax or additional cost system, study authors concluded in an exhaustive analysis of global emissions, climate policies and laws.

“The key ingredient if you want to reduce emissions is that you have pricing in the policy mix,” said study co-author Nicolas Koch, a climate economist at the Potsdam Institute for Climate Impact Research in Germany. “If subsidies and regulations come alone or in a mix with each other, you won’t see major emission reductions. But when price instruments come in the mix like a carbon energy tax then they will deliver those substantial emissions reductions.”

The study also found that what works in rich nations doesn’t always work as well in developing ones.

Still, it shows the power of the purse when fighting climate change, something economists always suspected, said several outside policy experts, climate scientists and economists who praised the study.

“We won't crack the climate problem in wealthier nations until the polluter pays,” said Rob Jackson, a Stanford University climate scientist and author of the book Clear Blue Sky. “Other policies help, but nibble around the edges.”

“Carbon pricing puts the onus on the owners and products causing the climate crisis,” Jackson said in an email.

A great example of what works is in the electricity sector in the United Kingdom, Koch said. That country instituted a mix of 11 different policies starting in 2012, including a phaseout of coal and a pricing scheme involving emission trading, which he said nearly halved emissions — “a huge effect.”

Of the 63 success stories, the biggest reduction was seen in South Africa's building sector, where a combination of regulation, subsidies and labeling of appliances cut emissions nearly 54%.

The only success story in the United States was in transportation. Emissions dropped 8% from 2005 to 2011 thanks to a mix of fuel standards — which amount to regulation — and subsidies.

Yet even the policy tools that seem to work still barely put a dent in ever-rising carbon dioxide emissions. Overall, the 63 successful instances of climate policies trimmed 600 million to 1.8 billion metric tons of the heat-trapping gas, the study found. Last year the world spewed 36.8 billion metric tons of carbon dioxide while burning fossil fuels and making cement.

If every major country somehow learned the lesson of this analysis and enacted the policies that work best, it would only shrink the United Nations “emissions gap” of 23 billion metric tons of all greenhouse gases by about 26%, the study found. The gap is the difference between how much carbon the world is on track to put in the air in 2030 and the amount that would keep warming at or below internationally agreed upon levels.

“It basically shows we have to do a better job,” said Koch, who is also head of the policy evaluation lab at the Mercator Research Institute in Berlin.

Niklas Hohne at Germany's New Climate Institute, who wasn't part of the study said: “The world really needs to make a step change, move into emergency mode and make the impossible possible.”

Koch and his team looked at emissions and efforts to reduce them in 41 countries between 1998 and 2022 —so it doesn't include the United States' nearly $400 billion in climate-fighting spending package passed two years ago as a cornerstone of President Joe Biden's environmental policy — and logged 1,500 different policy actions. They bunched the policies in four broad categories — pricing, regulations, subsidies and information — and analyzed four distinct sectors of the economy: electricity, transportation, buildings and industry.

In what Koch called “the reverse causal approach," the team looked for emission drops of 5% or more in different sectors of countries' economies and then figured out what caused them with help of observations and machine learning. Researchers compared emissions to similar nations as control groups and accounted for weather and other factors, Koch said.

The team created a statistically transparent approach that others can use to update or reproduce it, including an interactive website where users can choose nations and economic sectors to see what's worked. And it could eventually be applied to the 2022 Biden climate package, he said. That package was heavy on subsidies.

John Sterman, a management professor at MIT Sloan Sustainability Institute who wasn't part of the research, said politicians find it easier to pass policies that subsidize and promote low-carbon technologies. He said that's not enough.

“It's also necessary to discourage fossil fuels by pricing them closer to their full costs, including the costs of the climate damage they cause,” he said.

Follow Seth Borenstein on X at @borenbears

Read more of AP’s climate coverage at http://www.apnews.com/climate-and-environment

The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org .

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

Chapter: conclusion, c onclusion.

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

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

A CKNOWLEDGEMENTS

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

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

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

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

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

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

F OR FURTHER READING

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

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

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

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

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

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

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