In his May 23 column, Wall Street Journal columnist Pete Du Pont claimed that carbon dioxide is “not a pollutant” and repeatedly cited a misleading, industry-funded study on climate change to prove that the “truth about 'global warming' is much less dire than Al Gore wants you to think.” But Du Pont's numerous assertions -- on the danger posed by carbon dioxide, the temperature record in Greenland, the effect of the sun on global warming, and the threat of rising sea levels -- all misrepresent the underlying scientific research.

In a similar vein, nationally syndicated radio host Rush Limbaugh noted that the “Antarctica ice sheeting is actually increasing” as evidence that global warming theory is “unsupportable by facts.” But, in fact, only the interior Antarctic ice sheet is growing, which is considered proof of climate change.

Du Pont: C0₂ is not a pollutant

In his May 23 column, Du Pont asserted that carbon dioxide “is not a pollutant -- indeed it is vital for plant growth,” echoing a television commercial recently produced by the oil industry-funded Competitive Enterprise Institute (CEI). The ad noted that carbon dioxide is “essential to life. ... We breath it out; plants breath it in.” It concluded: “Carbon dioxide. They call it pollution. We call it life.” But, contrary to Du Pont's suggestion, scientists do not argue that carbon dioxide is inherently harmful. Rather, they point to the danger posed to the atmosphere by excessive discharges of CO2, as the Natural Resources Defense Council noted:

[A] pollutant is a substance that causes harm when present in excessive amounts. CO2 has been in the atmosphere since life on earth began, and in the right amounts CO2 is important for making the earth hospitable for continued life. But when too much CO2 is put into the atmosphere, it becomes harmful. We have long recognized this fact for other pollutants. For example, phosphorus is a valuable fertilizer, but in excess, it can kill lakes and streams by clogging them with a blanket of algae.

Du Pont: Greenland is experiencing a cooling trend

Du Pont's column relied heavily on the conclusions of a 2006 report, "Climate Science: Climate Change and Its Impacts," by David R. Legates, associate professor of geography and director of the Center for Climatic Research at the University of Delaware. The report was published by Du Pont's employer, the National Center for Policy Analysis, a conservative think tank that has received substantial funding from energy interests such as ExxonMobil Corp. Before repeating several of the report's findings, Du Pont noted its conclusion -- that “the science does not support claims of drastic increases in global temperatures over the 21st century, nor does it support claims of human influence on weather events and other secondary effects of climate change” -- which he described as “the reality about global warming and its impact on the world.”

Du Pont went on to cite Legates's finding that “the coastal stations in Greenland had actually experienced a cooling trend.” He quoted from the text of the report: "[A]verage summer air temperatures at the summit of the Greenland Ice Sheet, have decreased at the rate of 4 degrees F per decade since measurements began in 1987." Rather than examining this trend himself, as Du Pont suggested he had, Legates simply attributed this finding to a 2004 report by climate scientist Petr Chylek of the Los Alamos National Laboratory. But Legates and Du Pont ignored a study published by Chylek a year later that attributed this cooling trend to local climate patterns -- specifically, the North Atlantic Oscillations (NAO). Chylek then analyzed the temperature record in the Danmarkshavn region of Greenland -- an area on the northeastern coast apparently unaffected by the NAO -- and found that the warming rate there was 2.2 times faster than the global average. This corresponds with United Nations climate change models that show Greenland warming at a faster rate than the rest of the planet and partially explains the rapid deterioration of the Greenland ice sheet in recent years.

Du Pont: Global warming is caused by solar radiation

After asserting that “the world is not warming as much as environmentalists think it is,” Du Pont cited the Legates report to claim that "[w]hat warming there is turns out to be caused by solar radiation rather than human pollution." But in suggesting that the sun is the sole cause of the observed warming, Du Pont went further than even Legates, who argued that solar radiation has a significant effect on warming and should be incorporated into any climate models:

Another variable that climate models do not take into account is the effect of changes in solar radiation on the Earth's climate. Over the past 350 years, scientists have discovered cyclical changes in the Earth's climate due to solar activity -- such as increases and decreases in solar flares and sun spots. Some researchers have argued that solar variability may be responsible for about 0.45° F of warming between 1900 and 1990 -- just under half of the recent warming -- and about a third of the total warming since 1500. This is notable since approximately half of the observed 20th century warming occurred before 1940 and cannot be attributed to human causes.

Legates himself misrepresented the findings of the researchers in question -- in this case solar radiation experts Judith Lean and David Rind, whose 1999 study Legates cited. While he noted their finding that “solar variability may be responsible for about 0.45 degree F of warming between 1900 and 1990” in order to emphasize the degree to which the sun is to blame for global warming, Legates ignored their more relevant conclusion: that solar radiation has played only a small part in the warming observed in recent decades. Indeed, at a 1999 seminar hosted by the U.S Global Climate Change Research Program, Lean reportedly explained “that when the climate-warming energy represented by changes in the concentration of greenhouse gases is compared to that which is exerted by changes in the sun's radiation, the sun's effect is quite small.”

Media Matters previously noted that Du Pont, in his March 28 column, cited a report by the Washington Policy Center to emphasize the link between solar output and warming trends, but DuPont failed to note the authors' disclaimer that their findings do not undermine the theory that greenhouse gases are causing significant global warming.

Du Pont: Sea ice is not melting excessively

Du Pont also asserted that sea ice “is not melting excessively,” citing the United Nation's Intergovernmental Panel on Climate Change's (ICPP) so-called Third Assessment as proof. As both Du Pont and the Legates report noted, the Third Assessment, published in 2001, found "[n]o significant acceleration in the rate of sea level rise during the 20th century." But they both failed to mention the ICPP's prediction of a “global-average sea level rise from 0.11 to 0.77” meters (4.3 to 30.3 inches) during the 21^st century. Moreover, recent studies documenting the increased melting in Antarctica and Greenland, as well as studies of past ice sheet melting, have strengthened the case for accelerated sea-level rise over the course of the next century and, as the weblog RealClimate noted, “probably nudge us closer to the upper end of the IPCC predictions.”

Limbaugh: Antarctic ice sheet is growing

On the May 22 broadcast of his radio show, Limbaugh echoed Du Pont's criticism of global warming theory as unfounded and exaggerated. He claimed that the hysteria over climate change “is unsupportable by facts” and that the “Antarctica ice is actually increasing.” Limbaugh's assertion is similar to a claim from one of the CEI television commercials that the “Antarctic ice sheet is getting thicker, not thinner,” according to a recent study. But the primary author of the study in question, Curt Davis, has issued a statement refuting CEI's use of his research, as the weblog Think Progress noted. In the statement, Davis pointed out that he reported growth only for the interior Antarctic ice sheet. Rather than undermining global warming theory, this phenomenon is actually the result of climate change. Davis noted that "[i]t has been predicted that global warming might increase the growth of the interior ice sheet due to increased precipitation," a fact that he said had been “ignored by CEI in a deliberate effort to confuse and mislead the public.”

From the May 22 broadcast of The Rush Limbaugh Show:

LIMBAUGH: Al Gore is trying -- he's got this movie coming out. It's absurd. The Antarctica ice is actually increasing. This -- just this hysteric global warming is unsupportable by facts. It's not even supported by these wacko computer models anymore. But yet here comes Clinton endorsing the Al Gore position on this, which -- and Al Gore, by the way, Democrats are begging this guy to run for president again in 2008, and there are stories about how Hollywood contributors are just salivating at the chance to throw some more money at Al Gore.