Global Warming Consensus Does Not Exist Among Scientists

Published September 5, 2007

Randy Scholfield in his August 24 column (“Why do some deny global warming?”) wonders why so many people “resist the evidence of human-caused climate change.” After all, he writes, “the overwhelming consensus of mainstream science is clear.”

Scholfield is deeply confused about the subject, but it isn’t his fault. Media coverage of global warming confusing, and too many scientists have made careers out of issuing scaring predictions that aren’t supported by articles published in peer-reviewed journals.

Two recent surveys of scientists – one of 530 climate scientists conducted in 2003 by German scientists Dennis Bray and Hans von Storch and the second conducted in 2006 of members of the National Registry of Environmental Professionals – shed some light on what scientists really believe.

Most scientists (more than 80 percent) believe some global warming has occurred. The best estimate is that global temperatures have risen about 1 degree Fahrenheit during the past 100 years.

A majority of scientists, but certainly not all, believe the human presence is responsible for some part of the recent warming. Most scientists believe it is not yet possible to determine how much of the modern warming is the result of natural cycles and how much is due to human activities.

The scientific community is split down the middle on whether future warming would be moderate and benign, or severe and harmful. Most scientists don’t believe we can predict what future climates will look like. And there is no agreement at all on what, if anything, we should do about global warming.

So Scholfield is wrong to claim that there is a “consensus” that the modern warming is man-made and will be catastrophic. Like so many others who are confused by the current debate, he relies heavily on the claims of a United Nation’s agency, the Intergovernmental Panel on Climate Change (IPCC), which says its reports represent the views of some 2,000 scientists.

But the great majority of those scientists only comment on or contribute to a few pages of the much larger report. They expressly do not endorse the overall reports or the claims that appear in the “Summary for Policymakers,” which they do not help write or approve. Many of the scientists who participate in the IPCC process are, in fact, outspoken skeptics of man-made global warming.

There is only one empirical study ever done that appeared to support the claim of a consensus that global warming is man-made. It is a widely cited (but seldom examined) study by Naomi Oreskes, a professor of gender studies at the University of California – San Diego.

Oreskes examined abstracts of 928 articles published from 1993 to 2002 and found “none of the papers disagreed with the consensus position” that the recent warming of the Earth was due to human activities. Note that she didn’t claim a consensus in support of the idea that warming would be severe or harmful, or even that all of the papers agreed with the consensus position. No survey of the literature or of scientists has ever shown consensus on those claims.

When other researchers tried and failed to replicate Oreskes’ findings, she was forced to admit she had mis-identified the search terms used in her study. One scientist, Benny Peiser, reported that his own analysis of the scientific abstracts supposedly studied by Oreskes found only 13 (1 percent) explicitly endorse what she called the “consensus view” while 470 (42 percent) of the abstracts include the keywords “global climate change” but do not find or endorse any link to human activities.

On the day I’m writing this, is reporting that new research by Klaus-Martin Schulte, accepted for publication by the journal Energy and Environment, finds no consensus on global warming in academic journal articles appearing between 2004 and early 2007. Nearly as many articles explicitly refute the theory of man-made global warming as endorse it, while most articles are simply silent on the issue.

In light of all this, is it any wonder that many people are skeptical of predictions of climate catastrophe? Most people can sense when something is being hyped and oversold. But I do wonder why journalists, who really ought to know better, ignore the evidence in front of them and simply read from scripts provided by environmental advocacy groups and ambitious politicians. You don’t suppose it’s because they have an ideological agenda, do you?

Joseph Bast ([email protected]) is president of The Heartland Institute.

Editor: The 2003 survey of more than 530 climate scientists is available at . A summary of the 2006 survey of members of the National Registry of Environmental Professionals is available at

A quick check on Sourcewatch or ExxonSecrets will reveal that my organization, The Heartland Institute, has received funding in the past from ExxonMobil. The ExxonSecrets site contains much incorrect data, including a gross overstatement of the amount we actually received in recent years, and we are asking them to correct it. Most importantly, Heartland has never received more than 5% of its annual budget from all energy companies combined. It’s ridiculous to claim that this small amount of support compromises our objectivity.

I’ve been writing about global warming since the early 1990s, long before any oil companies contributed to Heartland, and will continue writing on the subject (I fear) long after they have stopped. Please do not dignify the effort by environmental groups to slander and demonize my organization. My research, and The Heartland Institute’s 23-year record of consistent advocacy of free-market ideas, ought to stand or fall on their merits.