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Essay on GLOBAL WARMING – Fact or Fiction CSS and PMS

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Gerald Marsh

Climate Change

Marinus C Gisolf

The present article on the subject of global warming and climate change in general arose from an observed confusion of contradictory publications, ambivalent environmental policies, questionable international agreements and popular climate theories with its supporters and opponents, creating serious doubts on what really is happening to our world. Temperatures in the atmosphere are on the rise and it seems that scientists, experts, politicians and the public in general have been able to notice this phenomenon for the last fifty years or so. The planet's climate changes continuously, which is another of the few statements we can be sure about, although the reasons behind it and its functionality with regards to global warming is still under investigation and discussion. This holds true even more for the question to what extent the human being can influence this rise in temperature and manage it through regulating its CO2 (carbon dioxide) emissions, which has led to extensive and even vehement debates. As part of a series of conversations among friends with different backgrounds and interests, we arrived at the basic questions: How important is the role of the human being in climate change? In search for answers we started to researching the Internet on these issues, which resulted in an intriguing journey full of surprises, contradictions, manipulations to the point that it became clear, that there are no simple explications or solutions. What did become clear is that our climate system is non-linear, chaotic with feedbacks, which makes it about impossible to forecast even tomorrow's weather.

Thermal Science

Professor Saumitra Mukherjee

Air temperature changes on Earth in recent years are the subject of numerous and increasingly interdisciplinary research. In contrast to, conditionally speaking, generally accepted views that these changes are conditioned primarily by anthropogenic activity, more results appear to suggest that it is dominant natural processes about. Whether because of the proven existence of areas in which downtrends are registered or the stagnation of air temperature, as opposed to areas where the increase is determined, in scientific papers, as well as the media, the increasingly present is the use of the term climate changes instead of the global warming. In this paper, we shall try to present arguments for the debate relating to the official view of the IPCC, as well as research indicating the opposite view.

Quaestiones Geographicae

cliff ollier

International Journal of Earth Science and Geophysics

David Blank

Luis Miranda

BRAZIL – Back in 2008, a report titled Nature, Not Human Activity, Controls the Climate was published by the Non-governmental International Panel on Climate Change (NIPCC). The report was an analysis of peer-reviewed papers and other published literature which purportedly studied climate change and how humanity contributed to the phenomenon. A total of 24 independent scientists participated in the review, which resulted in a 50 page document on the causes and consequences of climate change. This study was different because it included papers that the IPCC ignored and also because it did not start with the assumption that human activity is the main cause of climate change or global warming. The international coalition of independent scientists hit the nail on the head on two aspects. First, point out the fact that the IPCC, a political organization, “is pre-programmed to produce reports to support the hypotheses of anthropogenic warming and the control of greenhouse gases, as envisioned in the Global Climate Treaty.” In other words, the IPCC is not a scientific organization, but a cheerleader of what the United Nations sees as the human threat to enhancing naturally occurring climate change. The IPCC does not objectively analyze data in order to reach a scientific conclusion. Instead, it cherry picks material that best supports its theory of man-made global warming. The conclusion of the 2008 report was clear, as its title states: Nature, Not Human Activity, Controls the Climate. What does the NIPCC bases its conclusion on? The analysis states that although facts such as melting glaciers and disappearing Arctic sea ice are irrelevant when explaining the causes of any warming, because any kind of warming, either anthropogenic or natural would cause melting. “The hockey-stick analysis was beset with methodological errors, as has been demonstrated by McIntyre and McKitrick [2003, 2005] and confirmed by statistics expert Edward Wegman [Wegman et al. 2006],” reads the report. This statement refers to the infamous Hockey Stick Theory used by Al Gore in his disinformation piece “An Inconvenient Truth”. Instead of judging human influence on climate as the only cause of severe change, the NIPCC study shows that there have been periods of extreme warming and precede the Little Ice Age, such as the Medieval Climate Optimum, which, without any human influence, experienced much warmer temperatures than on the 20th or 21st centuries. Another important point that NIPCC makes in its report, is the weak relation between CO2 emissions and planetary warming. “The IPCC affirms that there is a correlation of global mean temperature with increases in atmospheric concentrations of carbon dioxide (CO2) in the twentieth century to support its conclusion. The argument sounds plausible; after all, CO2 is a GH gas and its levels are increasing. However, the correlation is poor and, in any case, would not prove causation,” says the document. To explain its conclusion, the NIPCC provides the trend recorded from climate behavior back in 1940-1975. According to data from satellites, while the amount of CO2 rose rapidly, the planet did not experience a warming trend. In fact, there hasn’t been any increase in warming since about 2001, even though CO2 emissions are continuing to rise. Besides analyzing the relation between CO2 emissions and warming, the NIPCC also studied the role of computer models in predicting global warming. The conclusion was that such models do not give any evidence of global warming The reason for this conclusion is that the parameters used in computer models are very limited in comparison with the total number of factors. Each computer model uses as few as 6 parameters of a total of 100 or more. Incidentally, the IPCC models always choose the ones that better justify the commonly publicized theory of anthropogenic warming, leaving out the rest. “The IPCC undervalues the forcing arising from changes in solar activity (solar wind and its magnetic effects) – likely much more important than the forcing from CO2. Uncertainties for aerosols, which tend to cool the climate and oppose the GH effect, are even greater, as the IPCC recognizes in atable on page 32 of the AR4 report,” says the NIPCC report. In 2009, the organization led by an international panel of nongovernment scientists and scholars published another report to rebut of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). The 2009 rebuttal took three years to be put together before being released in June of that year. The document was coauthored and edited by S. Fred Singer, Ph.D., and Craig Idso, Ph.D. and complemented by the work of contributions and reviews by a group of scientists from around the world. The paper titled “Climate Change Reconsidered” not only described the limitations of the IPCC’s attempt to forecast future climate, but also studied empirical data on past temperatures, reviewed observational data on glacier melting, sea ice area, variation in precipitation, and sea level rise, summarized the research of a growing number of scientists who say variations in solar activity, not greenhouse gases, are the true driver of climate change, investigated and debunked the widespread fears that global warming could cause more extreme weather, examined the biological effects of rising CO2 concentrations and warmer temperatures, examined the IPCC’s claim that CO2 increases in air temperature will cause unprecedented plant and animal extinctions and challenged the IPCC’s unscientific claim that CO2-induced global warming is harmful to human health. In their analysis, the independent scientists behind the 2009 report concluded that “global data on glaciers do not support claims made by the IPCC that most glaciers are retreating or melting.” Data for this analysis came from all over the world, including places like Africa, Antarctica, the Arctic, Europe, North America, and South America. On the issue of solar influence over climate cycles, the NIPCC paper reviewed recent and older literature which concluded that solar activity is the true driver of planetary climate. According to the literature, “cosmic ray variability was the major driver of changes in earth’s surface air temperature over the past millennium… this forcing was primarily driven by variations in solar activity, modulated by the more slowly changing geomagnetic field strength of the planet, which sometimes strengthened the solar forcing and sometimes worked against it.” The report indicates that the powerful influence of solar cosmic rays leave little room for only a small impact of anthropogenic CO2 emissions in the last two centuries. Continue reading: http://real-agenda.com/2014/04/11/climate-change-caused-by-dominant-natural-causes-not-humans/

The Complete Briefing

Calin Zamfirescu

Melkamu Alemayehu , Birhanu Bayeh

Global warming is a most burning topic gained the attention of many social thinkers such as scientists, policy makers, environmentalists, researchers and student worldwide. It is the increase of the average temperature on the Earth. The root cause for the increase of the temperature is global warming. As the Earth is getting warmer, disasters like hurricanes, disease and injury of heat waves, droughts, storms and floods are getting more frequent. Over the last 100 years, the average air temperature near the Earth’s surface has risen by a little less than 10C. The causes and consequences of global warming on the Earth`s environment have been reviewed in the present study. The controversy between scientists on the causes of global warming may be natural or may be caused by human interference. The natural causes were atmospheric carbon dioxide (CO2), Volcanic Eruptions, the dynamic system of the Earth, Sun, and Cosmos. Human activities have been emitting extra greenhouse gases, which w...

William Irwin

John Sweeney

The Earth's thermostat is a complex and delicate mechanism, at the heart of which lie the greenhouse gases in the atmosphere. Carbon dioxide (CO2), a colourless and odourless gas, is the principal well-mixed greenhouse gas. It is through emissions of this gas that human activities exert their greatest influence on climate. Increased concentrations of carbon dioxide disturb the natural radiative balance of the atmosphere and lead to warming of the Earth's surface. The latest report from the Intergovernmental Panel on Climate Change, the Fourth Assessment Report (2007), has confirmed the assertion that “warming of the climate system is unequivocal” and that most of the observed 20th century increase in globally averaged temperatures is “very likely” due to the observed increases in anthropogenic greenhouse gas concentrations. A discernable human influence on the climate system is now apparent and extends to oceanic warming, temperature extremes and wind patterns. Concentration...

The Global Warming Debate: Is It Real? Essay

Introduction, the impetus for global warming, the arguments backing the idea that global warming is a reality, the arguments backing the idea that global warming is fiction.

The debate on global warming is turning out to be controversial with one side dismissing it as a creation of dishonest scientists and the other dismissing the other as behaving like the proverbial ostrich that buried its head in sand thinking that it was safe only to receive a stinging bite on its uncovered nether from the hyena.

Regardless of the side that has the truth, it is very important to treat the issue of global warming with utmost attention given the potential it has for causing misery on the planet. Whether it is already here with us or it will be here fifty to one hundred years from now, the increased temperatures that come with global warming, as well as the increased precipitation that in turn lead to increased sea levels, are not something that will change earthly life for the better. It is for this reason that global warming needs to be investigated in an organized manner and the evidence evaluated to determine what we are facing. In this brief essay, I will attempt to convey the issues raised by the two opposing sides regarding global warming. The evidence availed by those who claim that it is already here with us will be presented as well as the rebuttals of those who oppose that position.

To start with, the case made by those who think that global warming is already here with us is as compelling as any case can be. The evidence that global warming is with us already begins with the increased temperatures on the surface of the earth (Philander2000, pp.4-5). Scientists have recorded increased temperatures in various parts of the planet and this is something that should worry everyone. The increase is significant because it is more than one degree on the Celsius scale (Ruddiman 2005, pp.12-17). The source of this increase in temperature is said to be the greenhouse gases that are emitted in large quantities from factories around the world. The most common greenhouse gas is carbon dioxide. The mechanism through which these greenhouse gases increase the earth’s surface temperature is that they trap heat and make it hard to escape thus making the atmosphere a huge hot greenhouse (Philander2000, pp.45-49).

The impact of increased temperatures is that precipitation in the form of rainfall has increased. There are numerous parts of Asia, the Americas, and Asia that are witnessing huge amounts of rainfall than it has ever been witnessed before. Floods resulting from these heavy rains have led to the destruction of both human, animal, and plant life. The result of the heavy rainfall is that the sea levels begin rising and this is something that has been proven. The evidence given in this case is that there are some islands in the major seas and oceans that have been submerged. A submerged island is a clear sign of increased water levels in the sea or ocean where the island is located (Houghton 1997, pp.34-36).

Far from rainfall and rising sea levels, ice and snow reservoirs in various parts of the planet have melted at a rate not witnessed before (Mathez 2009, pp.39-41). Mountains that were once beautiful with snow caps are now bare with rocky tops. What else can make ice and snowmelt from the top of mountains? Whatever it is, I am sure it is not cold. The South Pole and the North Pole that were once famous for their unchanging ice and snow levels are fast losing this reputation. This is a clear indication that the planet is gaining more heat than it should. Thus we are likely to witness more floods in some areas as we have already seen in some parts as mentioned in the above paragraph while some parts of the planet will experience scorching heat and therefore undergo desertification.

On the other hand, those who dismiss the alarm on global warming as false have tried their best to make their case as appealing as possible. They have done a commendable job of reducing the enormity of the discoveries made by those who think that global warming is already here and we, therefore, need to start taking immediate action. What do they say about greenhouse gases? They think that the amount of carbon dioxide has not increased on the planet (Horner 2008, pp.11-15). The plants make use of carbon dioxide in photosynthesis and therefore regulate the level of atmospheric carbon dioxide which is supposed to be around 3%.

In addition to the above, those who call global warming a fictitious ploy use their dismissal of the levels of greenhouse gases such as carbon dioxide to term the temperature shift of about one degree Celsius as normal rise and fall. They claim that it has been there throughout the history of the planet. They also dismiss the claim that ice and snow have disappeared as fictitious with the argument that it is a pattern that takes the form of the appearance and disappearance of snow caps on these mountain peaks through the climatic life of the planet.

The weaknesses of the second group which dismisses global warming are that they lack sufficient explanations for the disappearing islands and the flooding that is becoming common. They are also not availing any substantial explanation for the desertification that is being witnessed in many parts of the world.

In conclusion, the global warming issue as discussed above has two sides. One thinks the problem is already here and we need to take immediate mitigating measures while the other declares global warming a creation of scientists who have an enormous appetite for fiction. It is prudent that the issues raised by these two sides as discussed above are carefully analyzed and action taken given the seriousness of global warming; whether it is already here or a million years away. If it is here, it is good to deal with it and if it is not here, it is good to make it clear and safe the public from anxiety.

Horner, C., 2008. Red Hot Lies: How Global Warming Alarmists Use Threats, Fraud, and Deception to Keep You Misinformed (1 ST American ed.).New York: Regnery Press.
Houghton, J., 1997. Globa Warming: The Complete Briefing (2 nd ed.) .New York: Cambridge University Press.
Mathez, E., 2009. Climate Change: The Science of Global Warming and Our Energy Future (1 st ed.).New York: Columbia University Press.
Philander, G., 2000. Is the Temperature Rising? The Uncertain Science of Global Warming . New York: Princeton University Press.
Ruddiman, W., 2005. Earth’s Climate Past and Future . New York: Princeton University Press.
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global warming fact or fiction css essay

The Science of Climate Change Explained: Facts, Evidence and Proof

Definitive answers to the big questions.

Credit... Photo Illustration by Andrea D'Aquino

Supported by

By Julia Rosen

Ms. Rosen is a journalist with a Ph.D. in geology. Her research involved studying ice cores from Greenland and Antarctica to understand past climate changes.

Published April 19, 2021 Updated Nov. 6, 2021

The science of climate change is more solid and widely agreed upon than you might think. But the scope of the topic, as well as rampant disinformation, can make it hard to separate fact from fiction. Here, we’ve done our best to present you with not only the most accurate scientific information, but also an explanation of how we know it.

How do we know climate change is really happening?

How much agreement is there among scientists about climate change, do we really only have 150 years of climate data how is that enough to tell us about centuries of change, how do we know climate change is caused by humans, since greenhouse gases occur naturally, how do we know they’re causing earth’s temperature to rise, why should we be worried that the planet has warmed 2°f since the 1800s, is climate change a part of the planet’s natural warming and cooling cycles, how do we know global warming is not because of the sun or volcanoes, how can winters and certain places be getting colder if the planet is warming, wildfires and bad weather have always happened. how do we know there’s a connection to climate change, how bad are the effects of climate change going to be, what will it cost to do something about climate change, versus doing nothing.

Climate change is often cast as a prediction made by complicated computer models. But the scientific basis for climate change is much broader, and models are actually only one part of it (and, for what it’s worth, they’re surprisingly accurate ).

For more than a century , scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming. These gases make up just a small fraction of the atmosphere but exert outsized control on Earth’s climate by trapping some of the planet’s heat before it escapes into space. This greenhouse effect is important: It’s why a planet so far from the sun has liquid water and life!

However, during the Industrial Revolution, people started burning coal and other fossil fuels to power factories, smelters and steam engines, which added more greenhouse gases to the atmosphere. Ever since, human activities have been heating the planet.

We know this is true thanks to an overwhelming body of evidence that begins with temperature measurements taken at weather stations and on ships starting in the mid-1800s. Later, scientists began tracking surface temperatures with satellites and looking for clues about climate change in geologic records. Together, these data all tell the same story: Earth is getting hotter.

Average global temperatures have increased by 2.2 degrees Fahrenheit, or 1.2 degrees Celsius, since 1880, with the greatest changes happening in the late 20th century. Land areas have warmed more than the sea surface and the Arctic has warmed the most — by more than 4 degrees Fahrenheit just since the 1960s. Temperature extremes have also shifted. In the United States, daily record highs now outnumber record lows two-to-one.

Where it was cooler or warmer in 2020 compared with the middle of the 20th century

This warming is unprecedented in recent geologic history. A famous illustration, first published in 1998 and often called the hockey-stick graph, shows how temperatures remained fairly flat for centuries (the shaft of the stick) before turning sharply upward (the blade). It’s based on data from tree rings, ice cores and other natural indicators. And the basic picture , which has withstood decades of scrutiny from climate scientists and contrarians alike, shows that Earth is hotter today than it’s been in at least 1,000 years, and probably much longer.

In fact, surface temperatures actually mask the true scale of climate change, because the ocean has absorbed 90 percent of the heat trapped by greenhouse gases . Measurements collected over the last six decades by oceanographic expeditions and networks of floating instruments show that every layer of the ocean is warming up. According to one study , the ocean has absorbed as much heat between 1997 and 2015 as it did in the previous 130 years.

We also know that climate change is happening because we see the effects everywhere. Ice sheets and glaciers are shrinking while sea levels are rising. Arctic sea ice is disappearing. In the spring, snow melts sooner and plants flower earlier. Animals are moving to higher elevations and latitudes to find cooler conditions. And droughts, floods and wildfires have all gotten more extreme. Models predicted many of these changes, but observations show they are now coming to pass.

There’s no denying that scientists love a good, old-fashioned argument. But when it comes to climate change, there is virtually no debate: Numerous studies have found that more than 90 percent of scientists who study Earth’s climate agree that the planet is warming and that humans are the primary cause. Most major scientific bodies, from NASA to the World Meteorological Organization , endorse this view. That’s an astounding level of consensus given the contrarian, competitive nature of the scientific enterprise, where questions like what killed the dinosaurs remain bitterly contested .

Scientific agreement about climate change started to emerge in the late 1980s, when the influence of human-caused warming began to rise above natural climate variability. By 1991, two-thirds of earth and atmospheric scientists surveyed for an early consensus study said that they accepted the idea of anthropogenic global warming. And by 1995, the Intergovernmental Panel on Climate Change, a famously conservative body that periodically takes stock of the state of scientific knowledge, concluded that “the balance of evidence suggests that there is a discernible human influence on global climate.” Currently, more than 97 percent of publishing climate scientists agree on the existence and cause of climate change (as does nearly 60 percent of the general population of the United States).

So where did we get the idea that there’s still debate about climate change? A lot of it came from coordinated messaging campaigns by companies and politicians that opposed climate action. Many pushed the narrative that scientists still hadn’t made up their minds about climate change, even though that was misleading. Frank Luntz, a Republican consultant, explained the rationale in an infamous 2002 memo to conservative lawmakers: “Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly,” he wrote. Questioning consensus remains a common talking point today, and the 97 percent figure has become something of a lightning rod .

To bolster the falsehood of lingering scientific doubt, some people have pointed to things like the Global Warming Petition Project, which urged the United States government to reject the Kyoto Protocol of 1997, an early international climate agreement. The petition proclaimed that climate change wasn’t happening, and even if it were, it wouldn’t be bad for humanity. Since 1998, more than 30,000 people with science degrees have signed it. However, nearly 90 percent of them studied something other than Earth, atmospheric or environmental science, and the signatories included just 39 climatologists. Most were engineers, doctors, and others whose training had little to do with the physics of the climate system.

A few well-known researchers remain opposed to the scientific consensus. Some, like Willie Soon, a researcher affiliated with the Harvard-Smithsonian Center for Astrophysics, have ties to the fossil fuel industry . Others do not, but their assertions have not held up under the weight of evidence. At least one prominent skeptic, the physicist Richard Muller, changed his mind after reassessing historical temperature data as part of the Berkeley Earth project. His team’s findings essentially confirmed the results he had set out to investigate, and he came away firmly convinced that human activities were warming the planet. “Call me a converted skeptic,” he wrote in an Op-Ed for the Times in 2012.

Mr. Luntz, the Republican pollster, has also reversed his position on climate change and now advises politicians on how to motivate climate action.

A final note on uncertainty: Denialists often use it as evidence that climate science isn’t settled. However, in science, uncertainty doesn’t imply a lack of knowledge. Rather, it’s a measure of how well something is known. In the case of climate change, scientists have found a range of possible future changes in temperature, precipitation and other important variables — which will depend largely on how quickly we reduce emissions. But uncertainty does not undermine their confidence that climate change is real and that people are causing it.

Earth’s climate is inherently variable. Some years are hot and others are cold, some decades bring more hurricanes than others, some ancient droughts spanned the better part of centuries. Glacial cycles operate over many millenniums. So how can scientists look at data collected over a relatively short period of time and conclude that humans are warming the planet? The answer is that the instrumental temperature data that we have tells us a lot, but it’s not all we have to go on.

Historical records stretch back to the 1880s (and often before), when people began to regularly measure temperatures at weather stations and on ships as they traversed the world’s oceans. These data show a clear warming trend during the 20th century.

Global average temperature compared with the middle of the 20th century

+0.75°C

–0.25°

Some have questioned whether these records could be skewed, for instance, by the fact that a disproportionate number of weather stations are near cities, which tend to be hotter than surrounding areas as a result of the so-called urban heat island effect. However, researchers regularly correct for these potential biases when reconstructing global temperatures. In addition, warming is corroborated by independent data like satellite observations, which cover the whole planet, and other ways of measuring temperature changes.

Much has also been made of the small dips and pauses that punctuate the rising temperature trend of the last 150 years. But these are just the result of natural climate variability or other human activities that temporarily counteract greenhouse warming. For instance, in the mid-1900s, internal climate dynamics and light-blocking pollution from coal-fired power plants halted global warming for a few decades. (Eventually, rising greenhouse gases and pollution-control laws caused the planet to start heating up again.) Likewise, the so-called warming hiatus of the 2000s was partly a result of natural climate variability that allowed more heat to enter the ocean rather than warm the atmosphere. The years since have been the hottest on record .

Still, could the entire 20th century just be one big natural climate wiggle? To address that question, we can look at other kinds of data that give a longer perspective. Researchers have used geologic records like tree rings, ice cores, corals and sediments that preserve information about prehistoric climates to extend the climate record. The resulting picture of global temperature change is basically flat for centuries, then turns sharply upward over the last 150 years. It has been a target of climate denialists for decades. However, study after study has confirmed the results , which show that the planet hasn’t been this hot in at least 1,000 years, and probably longer.

Scientists have studied past climate changes to understand the factors that can cause the planet to warm or cool. The big ones are changes in solar energy, ocean circulation, volcanic activity and the amount of greenhouse gases in the atmosphere. And they have each played a role at times.

For example, 300 years ago, a combination of reduced solar output and increased volcanic activity cooled parts of the planet enough that Londoners regularly ice skated on the Thames . About 12,000 years ago, major changes in Atlantic circulation plunged the Northern Hemisphere into a frigid state. And 56 million years ago, a giant burst of greenhouse gases, from volcanic activity or vast deposits of methane (or both), abruptly warmed the planet by at least 9 degrees Fahrenheit, scrambling the climate, choking the oceans and triggering mass extinctions.

In trying to determine the cause of current climate changes, scientists have looked at all of these factors . The first three have varied a bit over the last few centuries and they have quite likely had modest effects on climate , particularly before 1950. But they cannot account for the planet’s rapidly rising temperature, especially in the second half of the 20th century, when solar output actually declined and volcanic eruptions exerted a cooling effect.

That warming is best explained by rising greenhouse gas concentrations . Greenhouse gases have a powerful effect on climate (see the next question for why). And since the Industrial Revolution, humans have been adding more of them to the atmosphere, primarily by extracting and burning fossil fuels like coal, oil and gas, which releases carbon dioxide.

Bubbles of ancient air trapped in ice show that, before about 1750, the concentration of carbon dioxide in the atmosphere was roughly 280 parts per million. It began to rise slowly and crossed the 300 p.p.m. threshold around 1900. CO2 levels then accelerated as cars and electricity became big parts of modern life, recently topping 420 p.p.m . The concentration of methane, the second most important greenhouse gas, has more than doubled. We’re now emitting carbon much faster than it was released 56 million years ago .

30 billion metric tons

Carbon dioxide emitted worldwide 1850-2017

Rest of world

Other developed

European Union

Developed economies

Other countries

United States

E.U. and U.K.

These rapid increases in greenhouse gases have caused the climate to warm abruptly. In fact, climate models suggest that greenhouse warming can explain virtually all of the temperature change since 1950. According to the most recent report by the Intergovernmental Panel on Climate Change, which assesses published scientific literature, natural drivers and internal climate variability can only explain a small fraction of late-20th century warming.

Another study put it this way: The odds of current warming occurring without anthropogenic greenhouse gas emissions are less than 1 in 100,000 .

But greenhouse gases aren’t the only climate-altering compounds people put into the air. Burning fossil fuels also produces particulate pollution that reflects sunlight and cools the planet. Scientists estimate that this pollution has masked up to half of the greenhouse warming we would have otherwise experienced.

Greenhouse gases like water vapor and carbon dioxide serve an important role in the climate. Without them, Earth would be far too cold to maintain liquid water and humans would not exist!

Here’s how it works: the planet’s temperature is basically a function of the energy the Earth absorbs from the sun (which heats it up) and the energy Earth emits to space as infrared radiation (which cools it down). Because of their molecular structure, greenhouse gases temporarily absorb some of that outgoing infrared radiation and then re-emit it in all directions, sending some of that energy back toward the surface and heating the planet . Scientists have understood this process since the 1850s .

Greenhouse gas concentrations have varied naturally in the past. Over millions of years, atmospheric CO2 levels have changed depending on how much of the gas volcanoes belched into the air and how much got removed through geologic processes. On time scales of hundreds to thousands of years, concentrations have changed as carbon has cycled between the ocean, soil and air.

Today, however, we are the ones causing CO2 levels to increase at an unprecedented pace by taking ancient carbon from geologic deposits of fossil fuels and putting it into the atmosphere when we burn them. Since 1750, carbon dioxide concentrations have increased by almost 50 percent. Methane and nitrous oxide, other important anthropogenic greenhouse gases that are released mainly by agricultural activities, have also spiked over the last 250 years.

We know based on the physics described above that this should cause the climate to warm. We also see certain telltale “fingerprints” of greenhouse warming. For example, nights are warming even faster than days because greenhouse gases don’t go away when the sun sets. And upper layers of the atmosphere have actually cooled, because more energy is being trapped by greenhouse gases in the lower atmosphere.

We also know that we are the cause of rising greenhouse gas concentrations — and not just because we can measure the CO2 coming out of tailpipes and smokestacks. We can see it in the chemical signature of the carbon in CO2.

Carbon comes in three different masses: 12, 13 and 14. Things made of organic matter (including fossil fuels) tend to have relatively less carbon-13. Volcanoes tend to produce CO2 with relatively more carbon-13. And over the last century, the carbon in atmospheric CO2 has gotten lighter, pointing to an organic source.

We can tell it’s old organic matter by looking for carbon-14, which is radioactive and decays over time. Fossil fuels are too ancient to have any carbon-14 left in them, so if they were behind rising CO2 levels, you would expect the amount of carbon-14 in the atmosphere to drop, which is exactly what the data show .

It’s important to note that water vapor is the most abundant greenhouse gas in the atmosphere. However, it does not cause warming; instead it responds to it . That’s because warmer air holds more moisture, which creates a snowball effect in which human-caused warming allows the atmosphere to hold more water vapor and further amplifies climate change. This so-called feedback cycle has doubled the warming caused by anthropogenic greenhouse gas emissions.

A common source of confusion when it comes to climate change is the difference between weather and climate. Weather is the constantly changing set of meteorological conditions that we experience when we step outside, whereas climate is the long-term average of those conditions, usually calculated over a 30-year period. Or, as some say: Weather is your mood and climate is your personality.

So while 2 degrees Fahrenheit doesn’t represent a big change in the weather, it’s a huge change in climate. As we’ve already seen, it’s enough to melt ice and raise sea levels, to shift rainfall patterns around the world and to reorganize ecosystems, sending animals scurrying toward cooler habitats and killing trees by the millions.

It’s also important to remember that two degrees represents the global average, and many parts of the world have already warmed by more than that. For example, land areas have warmed about twice as much as the sea surface. And the Arctic has warmed by about 5 degrees. That’s because the loss of snow and ice at high latitudes allows the ground to absorb more energy, causing additional heating on top of greenhouse warming.

Relatively small long-term changes in climate averages also shift extremes in significant ways. For instance, heat waves have always happened, but they have shattered records in recent years. In June of 2020, a town in Siberia registered temperatures of 100 degrees . And in Australia, meteorologists have added a new color to their weather maps to show areas where temperatures exceed 125 degrees. Rising sea levels have also increased the risk of flooding because of storm surges and high tides. These are the foreshocks of climate change.

And we are in for more changes in the future — up to 9 degrees Fahrenheit of average global warming by the end of the century, in the worst-case scenario . For reference, the difference in global average temperatures between now and the peak of the last ice age, when ice sheets covered large parts of North America and Europe, is about 11 degrees Fahrenheit.

Under the Paris Climate Agreement, which President Biden recently rejoined, countries have agreed to try to limit total warming to between 1.5 and 2 degrees Celsius, or 2.7 and 3.6 degrees Fahrenheit, since preindustrial times. And even this narrow range has huge implications . According to scientific studies, the difference between 2.7 and 3.6 degrees Fahrenheit will very likely mean the difference between coral reefs hanging on or going extinct, and between summer sea ice persisting in the Arctic or disappearing completely. It will also determine how many millions of people suffer from water scarcity and crop failures, and how many are driven from their homes by rising seas. In other words, one degree Fahrenheit makes a world of difference.

Earth’s climate has always changed. Hundreds of millions of years ago, the entire planet froze . Fifty million years ago, alligators lived in what we now call the Arctic . And for the last 2.6 million years, the planet has cycled between ice ages when the planet was up to 11 degrees cooler and ice sheets covered much of North America and Europe, and milder interglacial periods like the one we’re in now.

Climate denialists often point to these natural climate changes as a way to cast doubt on the idea that humans are causing climate to change today. However, that argument rests on a logical fallacy. It’s like “seeing a murdered body and concluding that people have died of natural causes in the past, so the murder victim must also have died of natural causes,” a team of social scientists wrote in The Debunking Handbook , which explains the misinformation strategies behind many climate myths.

Indeed, we know that different mechanisms caused the climate to change in the past. Glacial cycles, for example, were triggered by periodic variations in Earth’s orbit , which take place over tens of thousands of years and change how solar energy gets distributed around the globe and across the seasons.

These orbital variations don’t affect the planet’s temperature much on their own. But they set off a cascade of other changes in the climate system; for instance, growing or melting vast Northern Hemisphere ice sheets and altering ocean circulation. These changes, in turn, affect climate by altering the amount of snow and ice, which reflect sunlight, and by changing greenhouse gas concentrations. This is actually part of how we know that greenhouse gases have the ability to significantly affect Earth’s temperature.

For at least the last 800,000 years , atmospheric CO2 concentrations oscillated between about 180 parts per million during ice ages and about 280 p.p.m. during warmer periods, as carbon moved between oceans, forests, soils and the atmosphere. These changes occurred in lock step with global temperatures, and are a major reason the entire planet warmed and cooled during glacial cycles, not just the frozen poles.

Today, however, CO2 levels have soared to 420 p.p.m. — the highest they’ve been in at least three million years . The concentration of CO2 is also increasing about 100 times faster than it did at the end of the last ice age. This suggests something else is going on, and we know what it is: Since the Industrial Revolution, humans have been burning fossil fuels and releasing greenhouse gases that are heating the planet now (see Question 5 for more details on how we know this, and Questions 4 and 8 for how we know that other natural forces aren’t to blame).

Over the next century or two, societies and ecosystems will experience the consequences of this climate change. But our emissions will have even more lasting geologic impacts: According to some studies, greenhouse gas levels may have already warmed the planet enough to delay the onset of the next glacial cycle for at least an additional 50,000 years.

The sun is the ultimate source of energy in Earth’s climate system, so it’s a natural candidate for causing climate change. And solar activity has certainly changed over time. We know from satellite measurements and other astronomical observations that the sun’s output changes on 11-year cycles. Geologic records and sunspot numbers, which astronomers have tracked for centuries, also show long-term variations in the sun’s activity, including some exceptionally quiet periods in the late 1600s and early 1800s.

We know that, from 1900 until the 1950s, solar irradiance increased. And studies suggest that this had a modest effect on early 20th century climate, explaining up to 10 percent of the warming that’s occurred since the late 1800s. However, in the second half of the century, when the most warming occurred, solar activity actually declined . This disparity is one of the main reasons we know that the sun is not the driving force behind climate change.

Another reason we know that solar activity hasn’t caused recent warming is that, if it had, all the layers of the atmosphere should be heating up. Instead, data show that the upper atmosphere has actually cooled in recent decades — a hallmark of greenhouse warming .

So how about volcanoes? Eruptions cool the planet by injecting ash and aerosol particles into the atmosphere that reflect sunlight. We’ve observed this effect in the years following large eruptions. There are also some notable historical examples, like when Iceland’s Laki volcano erupted in 1783, causing widespread crop failures in Europe and beyond, and the “ year without a summer ,” which followed the 1815 eruption of Mount Tambora in Indonesia.

Since volcanoes mainly act as climate coolers, they can’t really explain recent warming. However, scientists say that they may also have contributed slightly to rising temperatures in the early 20th century. That’s because there were several large eruptions in the late 1800s that cooled the planet, followed by a few decades with no major volcanic events when warming caught up. During the second half of the 20th century, though, several big eruptions occurred as the planet was heating up fast. If anything, they temporarily masked some amount of human-caused warming.

The second way volcanoes can impact climate is by emitting carbon dioxide. This is important on time scales of millions of years — it’s what keeps the planet habitable (see Question 5 for more on the greenhouse effect). But by comparison to modern anthropogenic emissions, even big eruptions like Krakatoa and Mount St. Helens are just a drop in the bucket. After all, they last only a few hours or days, while we burn fossil fuels 24-7. Studies suggest that, today, volcanoes account for 1 to 2 percent of total CO2 emissions.

When a big snowstorm hits the United States, climate denialists can try to cite it as proof that climate change isn’t happening. In 2015, Senator James Inhofe, an Oklahoma Republican, famously lobbed a snowball in the Senate as he denounced climate science. But these events don’t actually disprove climate change.

While there have been some memorable storms in recent years, winters are actually warming across the world. In the United States, average temperatures in December, January and February have increased by about 2.5 degrees this century.

On the flip side, record cold days are becoming less common than record warm days. In the United States, record highs now outnumber record lows two-to-one . And ever-smaller areas of the country experience extremely cold winter temperatures . (The same trends are happening globally.)

So what’s with the blizzards? Weather always varies, so it’s no surprise that we still have severe winter storms even as average temperatures rise. However, some studies suggest that climate change may be to blame. One possibility is that rapid Arctic warming has affected atmospheric circulation, including the fast-flowing, high-altitude air that usually swirls over the North Pole (a.k.a. the Polar Vortex ). Some studies suggest that these changes are bringing more frigid temperatures to lower latitudes and causing weather systems to stall , allowing storms to produce more snowfall. This may explain what we’ve experienced in the U.S. over the past few decades, as well as a wintertime cooling trend in Siberia , although exactly how the Arctic affects global weather remains a topic of ongoing scientific debate .

Climate change may also explain the apparent paradox behind some of the other places on Earth that haven’t warmed much. For instance, a splotch of water in the North Atlantic has cooled in recent years, and scientists say they suspect that may be because ocean circulation is slowing as a result of freshwater streaming off a melting Greenland . If this circulation grinds almost to a halt, as it’s done in the geologic past, it would alter weather patterns around the world.

Not all cold weather stems from some counterintuitive consequence of climate change. But it’s a good reminder that Earth’s climate system is complex and chaotic, so the effects of human-caused changes will play out differently in different places. That’s why “global warming” is a bit of an oversimplification. Instead, some scientists have suggested that the phenomenon of human-caused climate change would more aptly be called “ global weirding .”

Extreme weather and natural disasters are part of life on Earth — just ask the dinosaurs. But there is good evidence that climate change has increased the frequency and severity of certain phenomena like heat waves, droughts and floods. Recent research has also allowed scientists to identify the influence of climate change on specific events.

Let’s start with heat waves . Studies show that stretches of abnormally high temperatures now happen about five times more often than they would without climate change, and they last longer, too. Climate models project that, by the 2040s, heat waves will be about 12 times more frequent. And that’s concerning since extreme heat often causes increased hospitalizations and deaths, particularly among older people and those with underlying health conditions. In the summer of 2003, for example, a heat wave caused an estimated 70,000 excess deaths across Europe. (Human-caused warming amplified the death toll .)

Climate change has also exacerbated droughts , primarily by increasing evaporation. Droughts occur naturally because of random climate variability and factors like whether El Niño or La Niña conditions prevail in the tropical Pacific. But some researchers have found evidence that greenhouse warming has been affecting droughts since even before the Dust Bowl . And it continues to do so today. According to one analysis , the drought that afflicted the American Southwest from 2000 to 2018 was almost 50 percent more severe because of climate change. It was the worst drought the region had experienced in more than 1,000 years.

Rising temperatures have also increased the intensity of heavy precipitation events and the flooding that often follows. For example, studies have found that, because warmer air holds more moisture, Hurricane Harvey, which struck Houston in 2017, dropped between 15 and 40 percent more rainfall than it would have without climate change.

It’s still unclear whether climate change is changing the overall frequency of hurricanes, but it is making them stronger . And warming appears to favor certain kinds of weather patterns, like the “ Midwest Water Hose ” events that caused devastating flooding across the Midwest in 2019 .

It’s important to remember that in most natural disasters, there are multiple factors at play. For instance, the 2019 Midwest floods occurred after a recent cold snap had frozen the ground solid, preventing the soil from absorbing rainwater and increasing runoff into the Missouri and Mississippi Rivers. These waterways have also been reshaped by levees and other forms of river engineering, some of which failed in the floods.

Wildfires are another phenomenon with multiple causes. In many places, fire risk has increased because humans have aggressively fought natural fires and prevented Indigenous peoples from carrying out traditional burning practices. This has allowed fuel to accumulate that makes current fires worse .

However, climate change still plays a major role by heating and drying forests, turning them into tinderboxes. Studies show that warming is the driving factor behind the recent increases in wildfires; one analysis found that climate change is responsible for doubling the area burned across the American West between 1984 and 2015. And researchers say that warming will only make fires bigger and more dangerous in the future.

It depends on how aggressively we act to address climate change. If we continue with business as usual, by the end of the century, it will be too hot to go outside during heat waves in the Middle East and South Asia . Droughts will grip Central America, the Mediterranean and southern Africa. And many island nations and low-lying areas, from Texas to Bangladesh, will be overtaken by rising seas. Conversely, climate change could bring welcome warming and extended growing seasons to the upper Midwest , Canada, the Nordic countries and Russia . Farther north, however, the loss of snow, ice and permafrost will upend the traditions of Indigenous peoples and threaten infrastructure.

It’s complicated, but the underlying message is simple: unchecked climate change will likely exacerbate existing inequalities . At a national level, poorer countries will be hit hardest, even though they have historically emitted only a fraction of the greenhouse gases that cause warming. That’s because many less developed countries tend to be in tropical regions where additional warming will make the climate increasingly intolerable for humans and crops. These nations also often have greater vulnerabilities, like large coastal populations and people living in improvised housing that is easily damaged in storms. And they have fewer resources to adapt, which will require expensive measures like redesigning cities, engineering coastlines and changing how people grow food.

Already, between 1961 and 2000, climate change appears to have harmed the economies of the poorest countries while boosting the fortunes of the wealthiest nations that have done the most to cause the problem, making the global wealth gap 25 percent bigger than it would otherwise have been. Similarly, the Global Climate Risk Index found that lower income countries — like Myanmar, Haiti and Nepal — rank high on the list of nations most affected by extreme weather between 1999 and 2018. Climate change has also contributed to increased human migration, which is expected to increase significantly .

Even within wealthy countries, the poor and marginalized will suffer the most. People with more resources have greater buffers, like air-conditioners to keep their houses cool during dangerous heat waves, and the means to pay the resulting energy bills. They also have an easier time evacuating their homes before disasters, and recovering afterward. Lower income people have fewer of these advantages, and they are also more likely to live in hotter neighborhoods and work outdoors, where they face the brunt of climate change.

These inequalities will play out on an individual, community, and regional level. A 2017 analysis of the U.S. found that, under business as usual, the poorest one-third of counties, which are concentrated in the South, will experience damages totaling as much as 20 percent of gross domestic product, while others, mostly in the northern part of the country, will see modest economic gains. Solomon Hsiang, an economist at University of California, Berkeley, and the lead author of the study, has said that climate change “may result in the largest transfer of wealth from the poor to the rich in the country’s history.”

Even the climate “winners” will not be immune from all climate impacts, though. Desirable locations will face an influx of migrants. And as the coronavirus pandemic has demonstrated, disasters in one place quickly ripple across our globalized economy. For instance, scientists expect climate change to increase the odds of multiple crop failures occurring at the same time in different places, throwing the world into a food crisis .

On top of that, warmer weather is aiding the spread of infectious diseases and the vectors that transmit them, like ticks and mosquitoes . Research has also identified troubling correlations between rising temperatures and increased interpersonal violence , and climate change is widely recognized as a “threat multiplier” that increases the odds of larger conflicts within and between countries. In other words, climate change will bring many changes that no amount of money can stop. What could help is taking action to limit warming.

One of the most common arguments against taking aggressive action to combat climate change is that doing so will kill jobs and cripple the economy. But this implies that there’s an alternative in which we pay nothing for climate change. And unfortunately, there isn’t. In reality, not tackling climate change will cost a lot , and cause enormous human suffering and ecological damage, while transitioning to a greener economy would benefit many people and ecosystems around the world.

Let’s start with how much it will cost to address climate change. To keep warming well below 2 degrees Celsius, the goal of the Paris Climate Agreement, society will have to reach net zero greenhouse gas emissions by the middle of this century. That will require significant investments in things like renewable energy, electric cars and charging infrastructure, not to mention efforts to adapt to hotter temperatures, rising sea-levels and other unavoidable effects of current climate changes. And we’ll have to make changes fast.

Estimates of the cost vary widely. One recent study found that keeping warming to 2 degrees Celsius would require a total investment of between $4 trillion and $60 trillion, with a median estimate of $16 trillion, while keeping warming to 1.5 degrees Celsius could cost between $10 trillion and $100 trillion, with a median estimate of $30 trillion. (For reference, the entire world economy was about $88 trillion in 2019.) Other studies have found that reaching net zero will require annual investments ranging from less than 1.5 percent of global gross domestic product to as much as 4 percent . That’s a lot, but within the range of historical energy investments in countries like the U.S.

Now, let’s consider the costs of unchecked climate change, which will fall hardest on the most vulnerable. These include damage to property and infrastructure from sea-level rise and extreme weather, death and sickness linked to natural disasters, pollution and infectious disease, reduced agricultural yields and lost labor productivity because of rising temperatures, decreased water availability and increased energy costs, and species extinction and habitat destruction. Dr. Hsiang, the U.C. Berkeley economist, describes it as “death by a thousand cuts.”

As a result, climate damages are hard to quantify. Moody’s Analytics estimates that even 2 degrees Celsius of warming will cost the world $69 trillion by 2100, and economists expect the toll to keep rising with the temperature. In a recent survey , economists estimated the cost would equal 5 percent of global G.D.P. at 3 degrees Celsius of warming (our trajectory under current policies) and 10 percent for 5 degrees Celsius. Other research indicates that, if current warming trends continue, global G.D.P. per capita will decrease between 7 percent and 23 percent by the end of the century — an economic blow equivalent to multiple coronavirus pandemics every year. And some fear these are vast underestimates .

Already, studies suggest that climate change has slashed incomes in the poorest countries by as much as 30 percent and reduced global agricultural productivity by 21 percent since 1961. Extreme weather events have also racked up a large bill. In 2020, in the United States alone, climate-related disasters like hurricanes, droughts, and wildfires caused nearly $100 billion in damages to businesses, property and infrastructure, compared to an average of $18 billion per year in the 1980s.

Given the steep price of inaction, many economists say that addressing climate change is a better deal . It’s like that old saying: an ounce of prevention is worth a pound of cure. In this case, limiting warming will greatly reduce future damage and inequality caused by climate change. It will also produce so-called co-benefits, like saving one million lives every year by reducing air pollution, and millions more from eating healthier, climate-friendly diets. Some studies even find that meeting the Paris Agreement goals could create jobs and increase global G.D.P . And, of course, reining in climate change will spare many species and ecosystems upon which humans depend — and which many people believe to have their own innate value.

The challenge is that we need to reduce emissions now to avoid damages later, which requires big investments over the next few decades. And the longer we delay, the more we will pay to meet the Paris goals. One recent analysis found that reaching net-zero by 2050 would cost the U.S. almost twice as much if we waited until 2030 instead of acting now. But even if we miss the Paris target, the economics still make a strong case for climate action, because every additional degree of warming will cost us more — in dollars, and in lives.

Veronica Penney contributed reporting.

Illustration photographs by Esther Horvath, Max Whittaker, David Maurice Smith and Talia Herman for The New York Times; Esther Horvath/Alfred-Wegener-Institut

An earlier version of this article misidentified the authors of The Debunking Handbook. It was written by social scientists who study climate communication, not a team of climate scientists.

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April 8, 2009

Is Global Warming a Myth?

How to respond to people who doubt the human impact on the climate

Dear EarthTalk: I keep meeting people who say that human-induced global warming is only theory, that just as many scientists doubt it as believe it. Can you settle the score? -- J. Proctor, London, UK

So-called “global warming skeptics” are indeed getting more vocal than ever, and banding together to show their solidarity against the scientific consensus that has concluded that global warming is caused by emissions from human activities.

Upwards of 800 skeptics (most of whom are not scientists) took part in the second annual International Conference on Climate Change—sponsored by the Heartland Institute, a conservative think tank—in March 2009. Keynote speaker and Massachusetts Institute of Technology meteorologist Richard Lindzen told the gathering that “there is no substantive basis for predictions of sizeable global warming due to observed increases in minor greenhouse gases such as carbon dioxide, methane and chlorofluorocarbons.”

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Most skeptics attribute global warming—few if any doubt any longer that the warming itself is occurring, given the worldwide rise in surface temperature—to natural cycles, not emissions from power plants, automobiles and other human activity. “The observational evidence…suggests that any warming from the growth of greenhouse gases is likely to be minor, difficult to detect above the natural fluctuations of the climate, and therefore inconsequential,” says atmospheric physicist Fred Singer, an outspoken global warming skeptic and founder of the advocacy-oriented Science and Environmental Policy Project.

But green leaders maintain that even if some warming is consistent with millennial cycles, something is triggering the current change. According to the nonprofit Environmental Defense, some possible (natural) explanations include increased output from the sun, increased absorption of the sun’s heat due to a change in the Earth’s reflectivity, or a change in the internal climate system that transfers heat to the atmosphere.

But scientists have not been able to validate any such reasons for the current warming trend, despite exhaustive efforts. And a raft of recent peer reviewed studies—many which take advantage of new satellite data—back up the claim that it is emissions from tailpipes, smokestacks (and now factory farmed food animals, which release methane) that are causing potentially irreparable damage to the environment.

To wit, the U.S. National Academy of Sciences declared in 2005 that “greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise,” adding that “the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action.” Other leading U.S. scientific bodies, including the American Meteorological Society, the American Association for the Advancement of Science and the American Geophysical Union have issued concurring statements—placing the blame squarely on humans’ shoulders.

Also, the Intergovernmental Panel on Climate Change (IPCC), a group of 600 leading climate scientists from 40 nations, says it is “very likely” (more than a 90 percent chance) that humans are causing a global temperature change that will reach between 3.2 and 7.2 degrees Fahrenheit by the end of this century.

CONTACTS : Heartland Institute, www.heartland.org ; Science and Environmental Policy Project, www.sepp.org ; U.S. National Academy of Sciences, www.nas.edu; IPCC , www.ipcc.ch.

EarthTalk is produced by E/The Environmental Magazine. SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk , P.O. Box 5098, Westport, CT 06881; [email protected] . Read past columns at: www.emagazine.com/earthtalk/archives.php . EarthTalk is now a book! Details and order information at: www.emagazine.com/earthtalkbook .

More From Forbes

5 big lies about climate change, and how researchers trained a machine to spot them.

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Protesters carry a sign reading "Tell The Truth" while walking in the street during the Shut Down DC ... [+] climate demonstration in Washington, D.C., U.S., on Monday, Sept. 23, 2019.

When it comes to climate change, the science is settled. So why does climate misinformation continue to spread online and in our media? And how are the climate deniers’ tactics changing? A pioneering new project has revealed new clues about such false claims and where they come from.

In the study, published by the journal Nature Scientific Reports , researchers identified a wide array of dubious climate claims, then programmed a computer to recognize them. The analysis has exposed the changing face of climate change denial, and details the ways in which powerful interest groups are attempting to delay climate action. Among the findings are new data to show how those spreading climate misinformation have switched over time from science denial—that is, claiming that climate science isn’t reliable—to solutions denial—the claim that solutions to slow or otherwise respond to climate change won’t work.

“One of the most valuable insights from our research was identifying the most prevalent categories of climate misinformation—attacks on the integrity of climate science, and misinformation targeting climate solutions,” said John Cook, a study author and postdoctoral research fellow with the Climate Change Communication Research Hub at Monash University. “This shows the value of using a model to provide an objective, quantitative analysis. My gut instinct was that science myths were much more prevalent than they actually are, when our analysis found they were a relatively small proportion of climate misinformation.”

Looking at climate-related content from 33 prominent climate contrarian blogs and 20 conservative think-tanks produced between 1998 and 2020, the team began by sorting the climate claims into brackets. They ultimately came up with five major themes of climate misinformation , namely: 1) Global warming is not happening; 2) Human-produced greenhouse gases are not causing global warming; 3) Climate impacts are not bad; 4) Climate solutions won’t work; and 5) Climate science or scientists are unreliable.

These five main themes were made up of 27 sub-claims and 49 sub-sub-claims, ranging from the humdrum “scientists are biased” trope to the otherwise true but completely irrelevant “CO2 is a trace gas” rhetorical ploy .

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These categories were then used to conduct what the researchers say is the “largest content analysis of contrarian claims to date.”

The analysis revealed that most climate misinformation does not take the form of climate myths—such as the falsehood that recent global heating is the result of a natural cycle—but rather focuses on undermining climate research and proposals to moderate and prepare for climate change.

The switch from outright “climate denial” to “solutions denial” likely came about because the scientific evidence for human-caused climate change is now so overwhelming. “Science denial has become untenable,” Cook told me. “So inevitably, opponents of climate action are strategically shifting to misinformation targeting climate solutions in order to delay climate policy.”

This aspect is important, he explained, “because most climate fact-checking focuses on science myths and have been largely neglecting the most prevalent forms of climate misinformation.”

Chart showing how different contrarian claims about climate change published by conservative think ... [+] tanks have changed over 20 years.

Indeed, while the conclusion of the COP26 climate summit last week left much to be desired , researchers noted that the conference did illustrate that the entire international community now accepted the physical science basis for climate change. “I'm proud because never before has science featured so strongly in the COP decisions,” said Joeri Rogelj, director of research and lecturer in climate change and the environment at the Grantham Institute, Imperial College London. “They frame and inform the urgency and requirements of the challenge ahead.”

Yet groups including the Union of Concerned Scientists say that wealthy special interest groups, including fossil fuel companies, continue to disseminate misinformation with the express purpose of delaying climate action.

“Ultimately the purpose of all climate misinformation is to delay climate action—whether the argument is ‘global warming isn’t happening’ or ‘climate models are unreliable,’” Cook said. “The conclusion is always ‘therefore we shouldn’t act on climate change.’”

The report also offers insights as to where the money behind climate misinformation is coming from. All the major donors revealed by the research were American, and included the influential Donors Capital Fund, the ExxonMobil Foundation and Koch Affiliated Foundations. Also included was the Vanguard Charitable Endowment Program, operated by investment firm Vanguard, which was revealed this year to be the largest investor in the global coal industry , to the tune of $86 billion.

So with climate misinformation now categorized and broadly understood, what can be done about it?

Researchers at the University of Cambridge wrote last month that while some climate myths had gained traction among 1,722 survey respondents, members of the public were generally rather adept at spotting bogus headlines. Among their recommendations, postdoctoral research associate Mikey Biddlestone and Sander van der Linden, a professor of social psychology in society at Cambridge, suggested social media and traditional media could do more to broadcast the views of experts, who are generally trusted by the public. Also effective, they said, is the tactic of “prebunking,” whereby media use stories that “pre-emptively refute short extracts of misinformation” which can help audiences to “develop mental antibodies that allow them to detect misinformation on their own in the future.”

“In order to counteract climate misinformation, we need to combine the findings from our machine learning research with other critical thinking research identifying the misleading rhetorical techniques and logical fallacies in each of the misinformation claims,” Cook said. “Combining these two separate lines of research into a single coherent work will bring us much closer to the holy grail of fact-checking.”

The full report, in Nature Scientific Reports, can be read here .

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10 myths about climate change

With the climate crisis becoming a hot topic in mainstream media - there's a lot of confusion around what climate change actually is and what's causing it. That's why we've tried to clear up some of the most frequently heard myths, so that you can tell fiction from fact!

Myth 1. The Earth’s climate has always changed

Over the course of Earth’s 4.5-billion-year history, the climate has changed a lot, this is true. However, the rapid warming we’re seeing now can't be explained by natural cycles of warming and cooling. The kind of changes that would normally happen over hundreds of thousands of years are happening in decades.

Global temperatures are now at their highest since records began. In fact, the 10 warmest years on Earth, since 1880, have occurred since 2014. [1]

So, when people talk about climate change today, they mean anthropogenic (human-made) climate change. This is the warming of Earth’s average temperature as a result of human activity, such as burning coal, oil and gas to produce energy to fuel our homes and transport, and cutting down trees to produce the food we eat. You can read more about it here: How do we know climate change is real?

Myth 2. Global warming isn't real as it's still cold

Global warming is causing the Earth’s average surface temperature to rise which, in turn, is causing changes in our natural climate systems. These changes are making all sorts of extreme weather events more likely and more severe, including more intense droughts, heatwaves and hurricanes but also, strangely, an increased potential for more severe cold weather events

There is also an important distinction between weather and climate. Weather refers to short-term changes in the Earth’s atmosphere and represents things such as temperature, rain and cloudiness. Climate refers to longer-term changes in the Earth’s atmosphere over extended periods of time. Short-term changes in the weather will continue and that is why we can still experience cold snaps, despite the fact that the Earth’s temperature is warming. On top of this, we will keep on experiencing natural seasonal variations as the Earth orbits around the sun, so winter will continue to feel cooler than summer, even though the overall temperature is higher than it was 100 years ago.

Due to where we are in the world, the UK and Ireland are likely to get more wind and rain as a result of climate change, while New York could see more snow. The complex interaction between factors in the Earth’s climate makes extreme weather events, both hot and cold, more unpredictable and impactful.

Myth 3. Heatwaves and wildfires have nothing to do with climate change

Climate change makes extreme weather more frequent and intense, including heatwaves, wildfires and floods.

The evidence shows that extreme heatwaves have increased since the 1950s and human-induced climate change is the main driver; with every additional increment of global warming, these extremes continue to increase.

Because climate change creates warmer and drier conditions, even if a wildfire is started as a result of human activity, there is more fuel available when vegetation is very dry, and the relative humidity of the air will be lower, allowing fires to spread further and faster. In addition, the global wildfire season is getting longer, due to higher temperatures and longer droughts.

Wildfires can pose an immediate threat to the lives of people and animals in the area, as well as causing damage to soil, vegetation and whole ecosystems. Smoke and ash from wildfires pollute air, water and land.

Myth 4. China is mostly responsible for climate change

Human-induced climate change is something that has been happening for many years and Western countries, like the UK, have played a big role in contributing to carbon emissions over the past 200 years. This means that only looking at who the biggest emitters of greenhouse gases are today is an oversimplification of a very nuanced topic.

A lot of the products we purchase in the UK are manufactured in China, meaning that we are essentially transferring a large portion of our emissions to the countries responsible for creating the products we use. Part of the reason emissions from highly industrialised countries are so high is because of the high demand for products created by them, from countries such as the UK.

Despite being one of the largest emitters of greenhouse gases today, in part because it’s such a big country, China’s emissions per person are less than other countries like the United States.

China is also currently investing heavily in renewable energy. The increase in investment has been in response to the rapid growth of green business, the demand for renewable energy and the need to clean up air pollution in its major cities.

Climate change is a global issue, and we all have a responsibility to step up to tackle the climate crisis. The problem will not be solved unless all countries put in as much effort as they can and work together. Action on climate change will need serious investment but has the potential to deliver huge benefits for nature and people. We all need to raise our voices and fight for our world!

Myth 5. Plants need carbon dioxide

Plants do need carbon dioxide (CO 2 ) to live. Plants and forests remove and store away huge amounts of carbon dioxide from the atmosphere each year. The problem is, there’s only so much carbon dioxide they can absorb and this amount is getting less, as more and more forests are cut down across the world, largely to produce our food.

Let’s be clear, CO 2 itself does not cause problems. It's part of the natural global ecosystem. The problem is the quantity of CO 2 that’s being produced by us as humans; there hasn’t been this level of CO 2 in the atmosphere for thee million years. [2]

Myth 6. Animals will adapt to climate change

This one isn't a complete myth; Darwin got the adaptation part right. However, let’s be clear, some plants and animals will adapt but not all.

To survive, plants, animals and birds confronted with climate change have two options: move or adapt. There are several examples of species that have begun to adapt to climate change already.

But increasingly, it's a different story for many. Given the speed of climate change, it’s becoming impossible for many species to adapt quickly enough to keep up with their changing environment. As habitats are destroyed by roads, cities and dams, moving becomes increasingly difficult. For those that can’t move or adapt, the future doesn’t look so positive.

Myth 7. Polar bear numbers are increasing

This isn’t the case. Climate change is the biggest threat faced by polar bears. The Arctic is warming roughly four times faster than the rest of the world, causing sea ice to melt earlier and form later each year. This makes it more difficult for female polar bears to get onto land in late autumn to build their dens and more difficult for them to get out onto the sea ice in the spring to feed their cubs. Their main source of prey, seals, are also affected by climate change, as they depend on sea ice to raise their young.

This means that in some parts of the Arctic, polar bears are having to survive with less food than they did previously. Polar bear populations are predicted to decline by 30% by the middle of this century.

Myth 8. Renewable energy is more expensive

The belief that renewable energy is expensive, simply isn’t true! Solar power and wind are the cheapest ways of generating electricity, meaning that the energy they produce is cheaper than nuclear, gas and other fossil fuels. Some estimates show that renewable energy can be up to nine times cheaper than gas! The cost of renewables has fallen faster than anyone could have predicted, yet the UK Government are still backing dirty fossil fuels. [3]

Right now, people are facing a huge rise in the price of energy and food. The main drivers of this include the price of fossil fuels, while crops around the world are also failing in the wake of droughts and floods caused by climate change. Tackling climate change and fixing the cost-of-living crisis go hand-in-hand. Both challenges have the same root cause – a reliance on expensive and polluting fossil fuels – meaning that both challenges have the same solution.

Myth 9. Renewable energy can only work when it's not cloudy or windy

The energy industry is developing new methods for storing electricity and managing demand at peak times, meaning that even if the sun isn't shining or it’s not blowing a gale, it’s still possible to rely on renewable energy sources.

The majority of UK homes get their electricity from the National Grid. When you switch to a clean supplier, they guarantee that for every unit of electricity you take out of the grid, they’ll put the same amount of clean energy back in, helping to clean up our energy supply.

Myth 10. Climate change is a future problem

There is no longer an excuse for inaction on climate change as it pushes the burden of addressing the climate crisis onto future generations.

We’re already seeing the devastating effects of climate change on global food supplies, migration, conflict, disease and global instability, which will only get worse if we don’t act now. Human-made climate change is the biggest crisis of our time. It threatens the future of the planet that we depend on for our survival and we're the last generation that can do something about it.

In 2015, 196 countries signed the Paris Agreement, uniting in the shared objective of halting global warming to 1.5°C (when compared to how hot the world was before the Industrial Revolution). To help with this, the UK is striving to reduce its carbon emissions by 68% by 2030 and is aiming to achieve net zero emissions by 2050. Therefore, in order for us to successfully achieve this goal, we need to act now.

Climate change is the greatest environmental challenge the world has ever faced, but we have the solutions and we know nature can fight back. We need people all over the world to take action and join the fight for our world

[1] Global Temperature: Vital Signs – Climate Change: Vital Signs of the Planet (nasa.gov)

[2] Climate Change: Atmospheric Carbon Dioxide: NOAA Climate.gov

[3] Analysis: Record-low price for UK offshore wind is nine times cheaper than gas - Carbon Brief

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 .

Order the book from Amazon here .

A new way to quantify climate change impacts: “outdoor days”.

A new measure of rising temperatures, called “outdoor days,” describes the number of days per year that outdoor temperatures are neither too hot nor too cold for people to go about normal outdoor activities, whether work or leisure, in reasonable comfort.

Making the clean energy transition work for everyone

The Energy Conference featured a keynote discussion between MIT President Sally Kornbluth and MIT’s Kyocera Professor of Ceramics Yet-Ming Chiang, in which Kornbluth discussed her first year at MIT as well as a recently announced, campus-wide effort to solve critical climate problems known as the Climate Project at MIT.

Letting the Earth answer back: Designing better planetary conversations

2023 Design Fellow Chen Chu MArch '21, explores the global relevance of local floodplain resilience strategies.

Cutting carbon emissions on the US power grid

An online model developed by an MIT Energy Initiative team enables other researchers and operators of U.S. regional grids to explore possible pathways to decarbonization. Case studies of the nine regional power grids shown here confirm the importance of designing a strategy based on the resources and electricity demand profiles of specific regions.

MIT Climate News in Your Inbox

Is global warming real?

Scientific consensus is overwhelming: The planet is getting warmer, and humans are behind it.

In recent years, global warming and climate change have been the subject of a great deal of political controversy, especially in the U.S. But as the science becomes clearer and consensus grows impossible to ignore, debate is moving away from whether humans are causing warming and toward questions about how best to respond.

Temperatures rising

Chart of GLOBAL LAND-OCEAN TEMPERATURE INDEX

Evidence of rising temperatures is pervasive and striking: Thermometer records kept over the past century and a half show Earth's average temperature has risen more than 1 degree Fahrenheit (0.9 degrees Celsius), and about twice that in parts of the Arctic .

That doesn’t mean temperatures haven't fluctuated among regions of the globe or between seasons and times of day. But by analyzing average temperatures all over the world, scientists have demonstrated an unmistakable upward trend.

This trend is part of climate change , which many people consider synonymous with global warming. 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 habitats, rising seas , and a range of other impacts.

All of these changes are emerging as humans continue to add heat-trapping greenhouse gases to the atmosphere.

How is climate change measured?

Although we can't look at thermometers going back thousands of years, we do have other records that help us figure out what temperatures were like in the distant past. For example, trees store information about the climate in the place they’re rooted. Each year trees grow thicker and form new rings. In warmer and wetter years, the rings are thicker. Old trees and wood can tell us about conditions hundreds or even thousands of years ago.

Windows on the past are also buried in lakes and oceans. Pollen, particles, and dead creatures fall to the bottom of oceans and lakes each year, forming sediments. Sediments contain a wealth of information about what was in the air and water when they fell. Scientists reveal this record by inserting hollow tubes into the mud to collect layers of sediment going back millions of years.

For a direct look at the atmosphere of the past, scientists drill cores through the Earth's polar ice sheets . Tiny bubbles trapped in the ice are actually samples from the Earth's past atmosphere, frozen in time. That's how we know that the concentrations of greenhouse gases since the Industrial Revolution are higher than they've been for hundreds of thousands of years.

Computer models help scientists to understand the Earth's climate, or long-term weather patterns. Models also allow scientists to make predictions about the future climate by simulating how the atmosphere and oceans absorb energy from the sun and transport it around the globe.

We are the reason

Several factors affect how much of the sun's energy reaches Earth's surface and how much of that energy gets absorbed. Those include greenhouse gases, particles in the atmosphere (from volcanic eruptions, for example), and changes in energy coming from the sun itself.

Climate models are designed to take such factors into account. For example, models have found that changes in solar irradiance and volcanic aerosols have contributed only about two percent of the recent warming effect over 250 years. The balance comes from greenhouse gases and other human-caused factors, such as land-use changes.

The speed and duration of this recent warming is remarkable as well. Volcanic eruptions, as an example, emit particles that temporarily cool the Earth's surface. But they have no lasting effect beyond a few years. Events like El Niño also work on fairly short and predictable cycles. On the other hand, the types of global temperature fluctuations that have contributed to ice ages occur on cycles of hundreds of thousands of years.

The answer to the question, “Is global warming real?” is yes: Nothing other than the rapid rise of greenhouse gas emissions from human activity can fully explain the dramatic and relatively recent rise in global average temperatures.

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How global warming is disrupting life on Earth

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Are there real ways to fight climate change? Yes.

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Climate Change: Science and Impacts Factsheet

The earth’s climate.

Climate change is altering temperature, precipitation, and sea levels, and will adversely impact human and natural systems, including water resources, human settlements and health, ecosystems, and biodiversity. The unprecedented acceleration of climate change over the last 50 years and the increasing confidence in global climate models add to the compelling evidence that climate is being affected by greenhouse gas (GHG) emissions from human activities. 2

Changes in climate should not be confused with changes in weather. Weather is observed at a particular location on a time scale of hours or days, and exhibits a high degree of variability, whereas climate is the long-term average of short-term weather patterns, such as the annual average temperature or rainfall. 3 Under a stable climate, there is an energy balance between incoming short wave solar radiation and outgoing long wave infrared radiation. Solar radiation passes through the atmosphere and most is absorbed by the Earth’s surface. The surface then re-emits energy as infrared radiation, a portion of which escapes into space. Increases in the concentrations of greenhouse gases in the atmosphere reduce the amount of energy the Earth’s surface radiates to space, thus warming the planet. 4

The Earth's Greenhouse Effect 1

Climate Forcings

Disturbances of the Earth’s balance of incoming and outgoing energy are referred to as positive or negative climate forcings. Positive forcings, such as GHGs, exert a warming influence on the Earth, while negative forcings, such as sulfate aerosols, exert a cooling influence. 5
Increased concentrations of GHGs from anthropogenic sources have increased the absorption of infrared radiation, enhancing the natural greenhouse effect. Methane and other GHGs are more potent, but CO₂ contributes most to warming because of its prevalence. 5
Anthropogenic GHG emissions, to date, amount to a climate forcing roughly equal to 1% of the net incoming solar energy, or the energy equivalent of burning 13 million barrels of oil every minute. 6

Climate Feedbacks and Inertia

•Climate change is also affected by the Earth’s responses to forcings, known as climate feedbacks. For example, the increase in water vapor that occurs with warming further increases surface warming and evaporation, as water vapor is a powerful GHG. 5
The volume of the ocean results in large thermal inertia that slows the response of climate change to forcings; energy balance changes result in delayed climate response with high momentum. 7
As polar ice melts, less sunlight is reflected and the oceans absorb more solar radiation. 5
Due to increasing temperature, large reserves of organic matter frozen in subarctic permafrost will thaw and decay, releasing additional CO₂ and methane to the atmosphere. 8 June 2020 was tied for the warmest on record and extreme temperatures in the Artic (especially Siberia) contributed to large wildfires and further thawing of permafrost. The fires alone were estimated to have released 59 million metric tons (Mt) of CO₂ into the atmosphere. 9
If GHG emissions were completely eliminated today, climate change impacts would still continue for centuries. 10 The Earth’s temperature requires 25 to 50 years to reach 60% of its equilibrium response. 11
Today’s emissions will affect future generations; CO₂ persists in the atmosphere for hundreds of years. 12

Human Influence on Climate

Separately, neither natural forcings (e.g., volcanic activity and solar variation) nor anthropogenic forcings (e.g., GHGs and aerosols) can fully explain the warming experienced since 1850. 13
Climate models most closely match the observed temperature trend only when natural and anthropogenic forcings are considered together. 13
In 2023, the Intergovernmental Panel on Climate Change (IPCC) concluded that: “human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850-1900 in 2011-2020.” 14

Modeled and Observed Global Average Temperatures 14

Observed Impacts

Physical systems.

Global average temperatures in 2022 were 0.86°C (1.55°F) higher than the 20th century average. 16
The warmest year on record since records began in 1880 was 2016, with 2020 ranking second. In 2020 global average land temperatures experienced a record high, while 2016 global ocean temperatures remain the highest on record. 17 The nine warmest years on record since 1880 have all occurred within the last nine years (2014-2022), and in 2022 annual global temperatures were above average for the 46th consecutive year. 16
Annual 2022 arctic temperatures rose to 0.73°C above the 1991-2020 average. Arctic sea ice is younger, thinner, and less expansive than in the 1980s and 90s. 18 The 2021 extent of ice reached the twelfth lowest annual cover on record since 1979, 4.92 million square kilometers. 19
U.S. average annual precipitation has increased by 4% since 1901, but the intensity and frequency of extreme precipitation events has increased even more, a trend that is expected to continue. 20
Global mean sea level has rose between 15 and 25 cm since 1901. Due to deep ocean warming and ice sheet melt, sea level rise is unavoidable and will continue for centuries to millennia. 14
Snow cover has noticeably decreased in the Northern Hemisphere. Current temperatures have risen 1.1°C and snow cover has decreased 1% relative to 1850-1900. Under a 4°C warming scenario, snow cover is predicted to decrease by 15%-30%. 10

Northwestern Glacier melt, Alaska, 1940-2005 18

Biological Systems

Warming that has already occurred is affecting the biological timing (phenology) and geographic range of plant and animal communities. 22
Often biological responses are not sufficient to handle the rapid spatial and temporal shifts that climate change is causing. Globally, approximately half of the species assessed have shifted polewards or to higher elevations. 14
Relationships such as predator-prey interactions are affected by these shifts, especially when changes occur unevenly between species. 23
Since the start of the 20th century, the average growing season in the contiguous 48 states has lengthened by nearly two weeks. 24

Predicted Changes

Increased temperature.

IPCC predicts global temperature will rise by 1.5°C (2.7°F) by the early 2030s.10 In the long term, global mean surface temperatures are predicted to rise 0.4-2.6°C (0.7-4.7°F) from 2045-2065 and 0.3-4.8°C (0.5-8.6°F) from 2081- 2100, relative to the reference period of 1986-2005. Since 1970, global average temperatures have been rising at a rate of 1.7°C per century, significantly higher than the average rate of decline of 0.01°C over the past 7,000 years. 5,25

Projected Near Surface Temperature Change Based on Warming Scenarios 10

rojected Near Surface Temperature Change Based on Warming Senarios10

Ocean Impacts

Models anticipate sea level rise between 26 and 77 cm for a 1.5°C increase in temperature by 2100. The rise is a result of thermal expansion from warming oceans and water added to the oceans by melting glaciers and ice sheets. 25
The oceans absorb about 31% of anthropogenic CO2 emissions, resulting in increased acidity. Coral reefs are projected to decline by 70–90% under a 1.5°C global warming senario. 14,26

Implications for Human and Natural Systems

This century, an unprecedented combination of climate change, associated disturbances, and other global change drivers will likely exceed many ecosystems’ capacities for resilience. 27 Risks associated with a warming scenario of 4°C include more frequent and intense hot and cold extreme temperatures, precipitation events, droughts, and hurricanes. 10
In 2023, the IPCC stated with very high confidence that “There is a rapidly closing window of opportunity to secure a livable and sustainable future for all.” 14
With an increase in average global temperatures of 2°C, nearly every summer would be warmer than the hottest 5% of recent summers. 28
Increased temperatures, changes in precipitation, and climate variability have increased the occurrence of food-borne and water-borne diseases. Vector-borne diseases are also occurring more often and in new geographic regions. 14,28
Although higher CO₂ concentrations and slight temperature increases can boost crop yields, the negative effects of warming on plant health and soil moisture lead to lower yields at higher temperatures. Intensified soil and water resource degradation resulting from changes in temperature and precipitation will further stress agriculture in certain regions. 28

Center for Sustainable Systems, University of Michigan. 2023. "Climate Change: Science and Impacts Factsheet." Pub. No. CSS05-19.

Adapted from image by W. Elder, National Park Service.
U.S. Global Change Research Program (USGCRP) (2009) Global Climate Change Impacts in the U.S.
National Oceanic and Atmospheric Administration (NOAA) (2019) “What’s the Difference Between Weather and Climate?”
National Aeronautics and Space Administration (2010) The Earth’s Radiation Budget.
Intergovernmental Panel on Climate Change (IPCC) (2013) Climate Change 2013: The Physical Science Basis.
CSS calculation based on data from UN Environment Programme (UNEP) and UN Framework Convention on Climate Change (UNFCCC) (2003) Climate Change Information Kit.
U.S. Environmental Protection Agency (EPA) (2016) Climate Change Indicators in the U.S., 2016.
UNEP (2012) Policy Implications of Warming Permafrost.
Cappucci, M. (2020) “Unprecedented heat in Siberia pushed planet to warmest June on record, tied with last year.” The Washington Post.
IPCC (2021) AR6 Climate Change 2021: The Physical Science Basis
Hansen, J., et al. (2005) Earth’s Energy Imbalance: Confirmation and Implications. Science, 229(3): 857.
Archer, D., et al. (2009) Atmospheric Lifetime of Fossil Fuel Carbon Dioxide. Annual Review of Earth and Planetary Sciences, 37: 117-34.
UNEP and GRID-Arendal (2005) Vital Climate Change Graphics.
Intergovernmental Panel on Climate Change (IPCC) (2023) Synthesis Report of the IPCC Sixth Assessment Report (AR6) Longer report.
Adapted from USGCRP (2009) Global Climate Change Impacts in the United States.
NOAA (2023) State of the Climate: 2022 Global Climate Report.
NOAA (2022) State of the Climate: 2021 Global Climate Report.
NOAA (2022) Arctic Report Card 2022.
NOAA (2021) Arctic Report Card 2021.
USGCRP (2018) Fourth National Climate Assessment.
Photo courtesy of the National Snow and Ice Data Center/World Data Center for Glaciology.
Secretariat of the Convention on Biological Diversity (2010) Global Biodiversity Outlook 3.
National Research Council (2009) Ecological Impacts of Climate Change.
U.S. EPA (2021) Climate Change Indicators: Length of Growing Season.
IPCC (2018) Global Warming of 1.5 C: Summary for Policy Makers, Chapter 1.
NOAA (2019) Global Ocean Absorbing More Carbon.
IPCC (2007) Climate Change 2007: Impacts, Adaptation and Vulnerability. Working Group II Contributions to the IPCC Fourth Assessment Report.
National Research Council (2011) Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to Millennia.

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Climate change: policy and mitigation factsheet », greenhouse gases factsheet ».

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This course uses ‘climate fiction’ to teach about the perils that a warming planet faces

Professor of English, John Carroll University

Disclosure statement

Debra J. Rosenthal does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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Text saying: Uncommon Courses, from The Conversation

Uncommon Courses is an occasional series from The Conversation U.S. highlighting unconventional approaches to teaching.

Title of course:

“Climate Change Literature”

What prompted the idea for the course?

After reading many fiction books that featured themes of climate change, I felt compelled to create a course that would allow students to do the same. The idea was to have students learn about our planetary crisis by exploring how it’s portrayed in literature.

At John Carroll University, students are required to take paired courses that are tethered together from two different departments. I approached a colleague who teaches a biology course about climate science to see if he wanted to link his course to mine. Students must co-enroll in both of our courses during the same semester. The combined courses give students both a scientific and literary view of climate change. In my colleague’s class, students learn about carbon dioxide emissions and the like. Then, in my class, they study how fiction writers and poets incorporate concerns about the effects of rising temperatures into their work.

What materials does the course feature?

The major work of fiction we read is Barbara Kingsolver’s novel “ Flight Behavior ,” about a low-income family in Appalachia. Millions of monarch butterflies become confused by warming temperatures and accidentally overwinter on the family farm, setting off much conflict. We also read lots of poetry and short fiction with themes of the impacts of planetary heating . We read some fiction by Kim Stanley Robinson, Paolo Bacigalupi, Tommy Orange, Olivia Clare, Jess Walter and more. Poets include Matthew Olzmann, Nickole Brown, Ross Gay, Dante Di Stefano and Craig Santos Perez.

What does the course explore?

By reading climate fiction and poetry, students learn how overreliance on fossil fuels overlaps with issues of economic injustice , racial disparities in climate impacts and climate migration . We explore narrative voice, structure, imagery, plot, dialogue, style and other textual concerns in creative works influenced by living in the Anthropocene – or the period, according to some scientists, when human activity began to significantly affect the planet’s climate and ecosystems. That period is thought by some climate change experts to have begun in the 1950s . Through classroom discussion, we share the collective experience of engaging with characters who navigate a threatened world.

To integrate the biology and English classes, the students’ final projects are pitches for a Hollywood movie that portrays a changed world due to planetary heating while also getting the science right. The assignment is harder than it sounds: Students must understand the harmful results of carbon emissions and craft a compelling story.

Why is this course relevant now?

Climate change is an existential crisis affecting us all right now . Many students do not study Earth science in high school; their first, and possibly only, exposure to evidence-based climate change happens in college. Authors address consequences such as warming temperatures, ocean acidification, desertification and sea-level rise. Thus, literature has become an essential tool to construct meaning in an age of climate disruption.

What’s a critical lesson from the course?

Literature helps us feel the immediacy of what’s at stake in a climate-changed world. The storytelling in fiction and poetry teaches us much that scientific and policy reports, charts, graphs and forecasts cannot. While data can predict rising sea levels, for example, a short story such as Tommy Orange’s “New Jesus” shows us how it feels to live in a submerged town where residents’ feet are always wet. Climate researchers predict the increasing desertification of the American Southwest. Through Paolo Bacigalupi’s short story “The Tamarisk Hunter,” readers experience what it looks like to see towns abandoned due to the lack of water, and golf courses where sand traps no longer exist because the entire course has turned to sand.

What will the course prepare students to do?

Analyzing fiction and poetry sharpens students’ critical interpretive skills and prepares them to think originally and creatively as they enter a workforce altered and threatened by climate change. For example, pre-health majors will see the impacts of climate change on the human body. Business majors will need to know how to operate when extreme weather and disrupted supply chains affect the bottom line.

Our two paired courses combine science and literature to equip students with expansive ways of asking questions about their role in the world.

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Essay. This essay sample was donated by a student to help the academic community. Papers provided by EduBirdie writers usually outdo students' samples. In the past 139years, the warming trend that we are having now has never experienced by earth before (NASA, 2020). In fact, the World Meteorological Organisation has stated that since 1980s ...
Responding to the Climate Threat: Essays on Humanity's Greatest
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 ...
PDF Climate Change: Science and Impacts
Cite as: Center for Sustainable Systems, University of Michigan. 2021."Climate Change: Science and Impacts Factsheet." Pub. No. CSS05-19. September 2021 Observed Impacts Physical Systems • Global average temperature was 0.98°C (1.76 °F) higher in 2020 than in the late 1800s.15 • The warmest year on record since records began in 1880 was 2016, with 2020 ranking
Global warming: Is it real? Get the facts.
Scientific consensus is overwhelming: The planet is getting warmer, and humans are behind it. In recent years, global warming and climate change have been the subject of a great deal of political ...
Global Warming: Fact or Fiction? Essay
Global warming, or what is now called climate change, is caused by the sunlight coming through the Earth's atmosphere, containing greenhouse gasses, and becoming cemented between the Earth's crust and Ozone layer. This causes an uncontrollable heating in the territory between them ("Global Warming Science").
Global warming
Modern global warming is the result of an increase in magnitude of the so-called greenhouse effect, a warming of Earth's surface and lower atmosphere caused by the presence of water vapour, carbon dioxide, methane, nitrous oxides, and other greenhouse gases. In 2014 the IPCC first reported that concentrations of carbon dioxide, methane, and ...
Essay on Global Warming with Samples (150, 250, 500 Words
Sample Essays on Global Warming. Here are some sample essays on Global Warming: Essay on Global Warming Paragraph in 100 - 150 words. Global Warming is caused by the increase of carbon dioxide levels in the earth's atmosphere and is a result of human activities that have been causing harm to our environment for the past few centuries now.
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Climate Change: Science and Impacts Factsheet
Ocean Impacts. Models anticipate sea level rise between 26 and 77 cm for a 1.5°C increase in temperature by 2100. The rise is a result of thermal expansion from warming oceans and water added to the oceans by melting glaciers and ice sheets. 25 The oceans absorb about 31% of anthropogenic CO2 emissions, resulting in increased acidity.
Global Warming: Fact Vs. Fiction Essay
In recent years, global climate change due to global warming has been largely researched. The paper, "Global Climate Change Triggered by Global Warming," offers compelling evidence from various scientific papers that the process of Earth's climate undergoing significant change has already begun and requires our attention due to the probability that human-generated greenhouse gases are ...
Global Warming : Fact Or Fiction? Essay
Global Warming: Fact or Fiction. The information found in this paper is designed to raise awareness of the ongoing debate surrounding global warming. The paper will provide readers with a clear description of global warming and signs recognized by those that believe it exist. It will address the same description and signs from the.
This course uses 'climate fiction' to teach about the perils that a
The major work of fiction we read is Barbara Kingsolver's novel " Flight Behavior ," about a low-income family in Appalachia. Millions of monarch butterflies become confused by warming ...
Is global warming fact or fiction?
Dear John, Global warming is a fact, and it is occurring. The planetary average temperature of the Earth's atmosphere at ground level is increasing. The Earth's climate has experienced many ...
[PDF] "GLOBAL WARMING": MYTH OR REALITY?
The "Global Warming scenario" is a hypothesis derived from theoretical models, asserted but not proven. There are numerous inconsistencies between predictions and actual observed climatic facts. The "global" thermal curve has no real significance in climatic terms. Climatic change is not global, but regional: for example, in the North Atlantic aerological unit, the Western side is ...
Climate Change and Global Warming Full Essay For Css
Climate Change and global warming full essay for css - Free download as PDF File (.pdf), Text File (.txt) or view presentation slides online. Climate Change and global warming full essay for css