Global Warming

Global Warming Contrarians and the Falsehoods They Promote

Global Warming Is Real.

We now have a scientific consensus, built over time through professional skepticism and review, that global warming is real, humans are responsible, and the effects of continuing with "business as usual" even for a few more years are dire. (See The Facts About Global Warming.)

In the face of this scientific consensus, a few global warming deniers – many of whom do not have relevant scientific expertise and are funded by industry – kick up dust, cloud the issues, change the subject, and say, "Well, we can’t be absolutely sure. Let’s just wait and see what happens." But if we wait, we may lose the ability to address the problem as certain unstoppable climate change processes are set in motion. We may well become committed to catastrophe.

The Scientific Consensus

The premier body on climate change is the Intergovernmental Panel on Climate Change (IPCC), formed in 1988 by the World Meteorological Organization and the United Nations Environment Programme. The IPCC, comprised of hundreds of scientists with relevant expertise from throughout the world, evaluates the state of climate science on the basis of peer-reviewed 1 and published scientific literature. In 2001, in the IPCC’s Third Assessment Report, the body expressed the scientific consensus that global warming is real and caused by humans. In its 2007 Fourth Assessment Report, the IPCC concluded, based on all available evidence, that it is very likely (+90%) that human activities are warming the planet. 2

Since the IPCC’s Third Assessment Report, all of the major scientific bodies in the United States with relevant expertise have issued reports or statements that confirm the IPCC's conclusion. These include: The National Academy of Sciences; 3 The American Meteorological Society; 4 American Geophysical Union; 5 and The American Association for the Advancement of Science. 6 Other scientific bodies throughout the world have done the same.

This is not to say that there are no open scientific questions related to global warming. We don’t know, for example, exactly how fast future climate changes may occur, or exactly how "feedback loops" might make things worse. 7  But the debate on certain fundamental points is over: global warming is real, it’s caused by human activities, we are already seeing effects, and the risk of future catastrophic changes is substantial under "business as usual."

And this is not to say that there are no open policy questions about global warming. For example, economists and politicians can argue about how much we are willing to spend on the problem, or about which countries should take the lead. But policy questions should not be confused with scientific ones.

top

Who’s Behind the Global Warming Deniers?

It’s well documented that many global warming deniers have ties to, or are funded by, members of coal and oil-related industries. These industry members will do whatever it takes to continue our dependence on fossil fuels and to delay the establishment of any alternatives. They have a vested interest in "business as usual."

As Newsweek recently reported, certain fossil fuel industry members and groups have spent a great deal of money to keep the true facts about global warming from the public.

Since the late 1980s, this well-coordinated, well-funded campaign by contrarian scientists, free-market think tanks and industry has created a paralyzing fog of doubt around climate change. Through advertisements, op-eds, lobbying and media attention, greenhouse doubters (they hate being called deniers) argued first that the world is not warming; measurements indicating otherwise are flawed, they said. Then they claimed that any warming is natural, not caused by human activities. Now they contend that the looming warming will be minuscule and harmless. 8

Of course, not every scientist who expresses doubt is funded by the fossil fuel industry. But, clearly, the industry is spending significant money to create the misleading impression that there is no scientific consensus and that the fundamental points about global warming are still open questions.

To take a recent, specific example, Newsweek reports that a conservative think tank funded by ExxonMobil offered scientists $10,000 to write articles undercutting the Intergovernmental Panel on Climate Change. Exxon’s campaign against climate change and the company’s funding of lobby groups that misrepresented the science spurred The Royal Society, the national academy of science of the United Kingdom, to send a letter to ExxonMobil, chastising the company for presenting an "inaccurate and misleading view of the science of climate change[,]" which includes funding organizations "that have been misinforming the public ...."9

Sound familiar? These tactics of misinformation are the same used by Big Tobacco to stall government regulation and to ensure that the public continued to use their products without a fear of cancer getting in the way. A famous tobacco industry document from the late 1960s could be describing the current global warming denial campaign: "Doubt is our product, since it is the best means of competing with the ‘body of fact’ that exists in the minds of the general public." 10

top

Clearing the Dust – Responses to Common Denier Myths

Below, set forth in italics, are some of the many myths and misleading questions that the deniers have been able to inject in the discussion of global warming. Responses from leading, authoritative sources, including the Intergovernmental Panel on Climate Change, the Met Office (UK), and The Royal Society, follow. 11 (Note: Open the links to view the accompanying graphs and charts.)

  1. Some places on Earth are cooling. Therefore, there’s no global warming.
    2. It’s true that a few places have cooled since the turn of the century. But this doesn’t mean that global warming isn’t occurring. Global warming describes the overall trend that scientists are seeing in global average temperatures. Global average temperatures are clearly rising – by about 0.74 degrees Celsius (1.33 degrees Fahrenheit) over the past 100 years. More of the warming has occurred in recent years. "An increasing rate of warming has taken place over the last 25 years, and 11 of the 12 warmest years on record have occurred in the past 12 years.... Confirmation of global warming comes from warming of the oceans, rising sea levels, glaciers melting, sea ice retreating in the Arctic and diminished snow cover in the Northern Hemisphere." (IPCC 4th, Working Group (WG) I, FAQ 3.1.)
  2. There was a drop in global average temperatures mid-century. Therefore, there’s no global warming.
    3. According to the IPCC, the global average temperature increase of .74 degrees Celsius (1.33 degrees Fahrenheit) over the last century occurred in two phases. First there was an increase of 0.35 degrees Celsuis (.63 degrees Fahrenheit) in the global average temperature from the 1910s to the 1940s, followed by a slight cooling of 0.1 degrees Celsius (.18 degrees Fahrenheit), and then a rapid warming of 0.55 degrees Celsius (.99 degrees Fahrenheit) up to the end of 2006. The mid-century dip in global average temperatures was caused by increased industrializaton after World War II, which led to increased aerosol pollution, which, overall, tends to have a cooling effect. The slight drop in global average temperatures observed mid-century, therefore, does not in anyway disprove global warming. (IPCC 4th, WG I, FAQs 2.1, 3.1, and 9.2.)
  3. The ice is becoming thicker in some parts of Antarctica. Therefore, there’s no global warming. Again, global warming means an increase in global average temperatures. "Observations show a global-scale decline of snow and ice over many years, especially since 1980 and increasing during the past decade, despite growth in some places and little change in others ...." Coastal regions of the ice sheets in West Antarctica are thinning and contributing to sea level rise. (IPCC 4th, WG I, FAQ 4.1.)
    Not every place on the planet warms uniformly, and there is significant regional variability. The ice in some parts of high-altitude East Antarctica is increasing, probably because of increases increase in precipitation over that region. (IPCC 4th, WG I, FAQ 4.1.) Because the area is still below freezing, precipitation falls as snow, which increases the thickness of the ice. All of this is no surprise to reputable climate scientists. The IPCC’s 2001 Report predicted that the ice in "the Antarctic ice sheet is likely to gain mass because of greater precipitation ...." (The Royal Society, A guide to facts and fictions about climate change.)

    top

  4. In the Earth’s history, the climate has been as warm, and even warmer than today. Therefore, global warming is natural. Climate changes in the past had different causes, such as changes in the Earth’s orbit that changed the amount of solar radiation reaching the Earth, changes in solar output, and volcanic activity. "The fact that natural factors caused climate changes in the past does not mean that the current climate change is natural. By analogy, the fact that forest fires have long been caused naturally by lightning strikes does not mean that fires cannot also be caused by a careless camper." (IPCC, WG I, FAQ 6.1.)
    The rate that humans are changing the atmospheric concentrations of greenhouse gases is unprecedented and far from natural. "The concentration of CO2 is now known accurately for the past 650,000 years from antarctic ice cores. During this time, CO2 concentration varied between a low of 180 ppm during cold glacial times and a high of 300 ppm during warm interglacials. Over the past century, it rapidly increased well out of this range, and is now 379 ppm.... For comparison, the approximately 80-ppm rise in CO2 concentration at the end of the past ice ages generally took over 5,000 years. Higher values than at present have only occurred many millions of years ago .... [G]lobal warming at the end of an ice age was a gradual process taking about 5,000 years .... It is thus clear that the current rate of global climate change is much more rapid and very unusual in the context of past changes. (IPCC, WG I, FAQ 6.2.)
    "Although some regions of the world experienced significantly warmer or colder periods during the last 1000 years, such as the ‘Medieval Warm Period’ and the ‘Little Ice Age’, these were not worldwide changes like the increase in global average temperature recorded during the 20th century." (The Royal Society, A guide to facts and fictions about climate change.) While some regions may have experienced localized warming, "the idea of a global or hemispheric ‘Medieval Warm Period’ that was warmer than today however, has turned out to be incorrect." (See National Oceanic and Atmospheric Administration, A Paleo Perspective on Global Warming, The "Medieval Warm Period".)
  5. The climate is quite variable. The climate we’re seeing today is probably just the result of natural variability. "It is very unlikely that the 20th-century warming can be explained by natural causes. The late 20th century has been unusually warm. Palaeoclimatic reconstructions show that the second half of the 20th century was likely the warmest 50-year period in the Northern Hemisphere in the last 1300 years. This rapid warming is consistent with the scientific understanding of how the climate should respond to a rapid increase in greenhouse gases like that which has occurred over the past century, and the warming is inconsistent with the scientific understanding of how the climate should respond to natural external factors such as variability in solar output and volcanic activity." (IPCC 4th, WG I, FAQ 9.2; see also Met Office, FAQ 2.2.)
  6. There’s no evidence that global warming will be bad for people. In fact, warming may be good for people. As The Royal Society has noted, "[t]he IPCC models acknowledge that some parts of the globe would benefit, at least in the short-term, from climate change. Some high northern latitudes could experience less extreme cold and a longer growing season for crops. In addition, the higher concentrations of carbon dioxide in the atmosphere will boost growth of some important crops, and given adequate water and nutrients, will bring higher yields. However, the IPCC models indicate that ‘the larger the changes and rate of change in climate, the more the adverse effects predominate.’ These adverse effects would be most severe in the tropics and subtropics. The IPCC pointed out that ‘reducing the projected increase in climate extremes is expected to benefit all countries, particularly developing countries, which are considered to be more vulnerable to climate change than developed countries.’" (The Royal Society, A guide to facts and fictions about climate change.)
    In a warming world, we can expect to see many adverse impacts, including increases in the frequency and intensity of extreme weather events, such as heat waves, droughts, floods and hurricanes (IPPC 4th, WG I, FAQs 3.2, 10.1); further melting of permafrost (IPCC 4th WG I, FAQ 4.1), affecting communities and infrastructure that have been built on it; and rising sea levels (IPCC 4th, WG I, FAQ 5.1) displacing island and low-lying coastal communities.
  7. Natural emissions of carbon dioxide are much greater than those from human activities. It follows that these emissions must be causing global warming. It’s true that natural emissions of carbon dioxide are greater than those from human activities. But natural exchanges of carbon dioxide have been in balance for many thousands of years, leading to the pre-industrial concentration of carbon dioxide remaining steady at about 280 ppm. Human caused emissions, primarily from the burning of fossil fuels, has had the effect of unbalancing the carbon budget and leading to the rise in concentrations seen since about 1850. (Met Office, FAQs, Question 2.7.)
    It is clear that "increases in atmospheric carbon dioxide (CO2) and other greenhouse gases during the industrial era are caused by human activities." (IPCC 4th, WG 1, FAQ 7.1.)

    top

  8. Solar output has increased in the industrial era. It’s therefore likely that the sun is causing global warming. Scientists use the term "forcing" to describe a factor that can cause a change in the climate by affecting the Earth’s energy balance. The only natural forcing that has occurred since the start of the industrial era is an increase in the sun’s output, or solar irradiance. While solar irradiance has had a positive effect on global average temperatures, that effect is very small as compared to human-caused increases in greenhouses gases. "[I]n today’s atmosphere, the radiative forcing from human activities is much more important for current and future climate change than the estimated radiative forcing from natural processes." (IPCC 4th, GW I, FAQ 2.1; see also Met Office FAQ 2.4.)
  9. The models used to make projections of future climate change are unreliable. It’s true that the models still show some errors at smaller scales, and in a few areas relating to the larger scale, such as simulating tropical precipitation. Part of the problem is that some of these larger scale effects are caused by small-scale processes, for example, clouds, that can only be approximated in today’s models. Confidence in the models is higher for changes in temperature than changes in precipitation (in part because of the limitations of the models as they related to clouds). This doesn’t mean that the models are unreliable, but only that they are limited.
    The models are based on what scientists know about the physics of climate, and, when the results of modeling are compared to observed temperatures, there is very close agreement. (IPCC 4th, WG I, FAQ 8.1.) As the IPPC states:
    "[C]onfidence in models comes from their physical basis, and their skill in representing observed climate and past climate changes. Models have proven to be extremely important tools for simulating and understanding climate, and there is considerable confidence that they are able to provide credible quantitative estimates of future climate change, particularly at larger scales. Models continue to have significant limitations, such as in their representation of clouds, which lead to uncertainties in the magnitude and timing, as well as regional details, of predicted climate change. Nevertheless, over several decades of model development, they have consistently provided a robust and unambiguous picture of significant climate warming in response to increasing greenhouse gases." (IPCC 4th, WG I, FAQ 8.1; see also Met Office, FAQ 2.10.)
    Moreover, as the Royal Society has noted: "Critics of the IPCC have not offered alternative numerical models that give different results for how climate will be affected by the range of possible future concentrations of greenhouse gases in the atmosphere." (The Royal Society, A guide to facts and figures about climate change.)
  10. Weather forecasts aren't accurate for more than a few days ahead. How can scientists possibly predict the future climate? "A common confusion between weather and climate arises when scientists are asked how they can predict climate 50 years from now when they cannot predict the weather a few weeks from now. The chaotic nature of weather makes it unpredictable beyond a few days.... Projecting changes in climate due to changes in greenhouse gases 50 years from now is a very different and much more easily solved problem than forecasting weather patterns just weeks from now. To put it another way, long-term variations brought about by changes in the composition of the atmosphere are much more predictable than individual weather events. As an example, while we cannot predict the outcome of a single coin toss or roll of the dice, we can predict the statistical behaviour of a large number of such trials." (IPCC 4th, WG I, FAQ 1.2; see also Met Office, FAQ 2.11.)
  11. Scientists are exaggerating the evidence by suggesting that global warming is causing extreme weather. Events like Hurricane Katrina in 2005 or the European heat waves of 2003 would have happened anyway. This is a red herring. Climate change scientists are not saying that global warming caused Hurricane Katrina or any other individual weather event.
    "In general, it is not possible to state categorically that individual weather events are due to changes in climate, and reputable scientists are extremely cautious about such claims. However, there is a link, albeit complex, between changes in climate and regional and local weather events, including extreme ones. Changes in the global climate can be expected to lead to patterns of local and regional weather events, particularly extreme ones. While scientists may be able to estimate the change in the likelihood of such events because of climate change, they cannot predict individual events." (The Royal Society, A guide to facts and figures about climate change.)
    What reputable scientists are saying is that, as the world has warmed in recent decades, we have seen an overall increase the frequency and severity of extreme weather events. For example, there has been an 75% increase in category 4 and 5 hurricanes since 1970. (IPCC 4th, WG I, FAQ 3.3.) "[O]ver the 20th century, human influences more than doubled the risk of having a summer in Europe as hot as that of 2003 ...." (IPCC 4th, WG I, FAQ 9.1.) As the Earth’s climate changes, even with relatively small mean climate changes, we can expect to see further increases in extreme weather events, including heat waves, droughts, floods and hurricanes. (IPCC 4th, WG I, FAQ 10.1.)
  12. We shouldn’t act until there is complete scientific certainty about every aspect of global warming. We now have a great deal of certainty about the problem of global warming, its causes, and the anticipated results for the future if we don’t take action today. It is important to remember that in science, there is no such thing as 100% certainty. Thus, global warming deniers who want 100% certainty are demanding the impossible. Of course, the predictions for future climate change under various levels of human emissions are just that – predictions. They are not certain to occur. As a society, we make decisions to guard against the risk of future harm every day. We regulate air and water pollutants without waiting for dead bodies. We require safety precautions for dams and nuclear power plants to protect us against low probability but potentially catastrophic accidents. We purchase insurance to guard against uncertain risks from floods, hurricanes, and fires. We do so because waiting until every last doubt is resolved may very well be too late.

  1. "Peer Review" is a process used by scientific and scholarly journals to ensure that the articles they publish represent the best scholarship available. When an article is submitted to a peer-reviewed journal, the editors send it out to other experts in the same field (the author’s peers) for review of the article’s quality, accuracy and relevance. Journals and publications that aren’t peer-reviewed rely only on the judgment of the editors, who are limited in number and may not have any relevant expertise.
  2. IPCC 4th, Working Group I: The Physical Basis for Climate Change, Summary for Policymakers at pp. 3, n.7; 10.
  3. See NAS, Climate Change Science: An Analysis of Some Key Questions (2001).
  4. See AMS, Climate Change – An Information Statement of the American Meteorological Society (Adopted by AMS Council on 1 February 2007) Bull. Amer. Met. Soc., 88.
  5. AGU, Human Impacts on Climate (adopted by AGU Council Dec. 2003).
  6. AAAS, Board Statement on Climate Change (Dec. 9, 2006).
  7. "Feedback" describes a self-sustaining process that, once set in motion, increases global warming. Ocean warming is a good example. As the oceans become warmer, they become less able to absorb carbon dioxide, a greenhouse gas. As a result, more carbon dioxide stays in the atmosphere, increasing the greenhouse effect. As the increased carbon dioxide in the atmosphere causes the planet to warm, the oceans warm even more, and absorb even less carbon dioxide, resulting in even higher atmospheric concentrations of the gas, and even higher temperatures.
  8. Sharon Begley, The Truth About Denial, Newsweek, August 13, 2007.
  9. See Letter from the Royal Society dated September 6, 2006.
  10. Jennifer Washburn, Science’s Worse Enemy: Corporate Funding, Discover, Oct. 11, 2007.
  11. See The Met Office (UK), Frequently asked questions, Questions about climate change; The Royal Society, A guide to facts and fictions about climate change, March 2005; Intergovernmental Panel on Climate Change, Frequently Asked Questions, Fourth Assessment Report, Working Group I, 2007.

top