Scientific consensus on climate change

Wednesday, May 28, 2008

As scientific evidence regarding the hazards of tobacco became overwhelming, a tobacco industry document outlined the basis for the countercampaign: "Doubt is our product, since it is the best means of competing with the body of fact that exists." Fortunately, tobacco manufacturers were unable to derail sane legislation designed to warn the public of the hazards.

When a scientific consensus developed about the destructive impact of chlorofluorocarbons on atmospheric ozone, another campaign was launched by so-called skeptics to deny the consensus and discredit the research. Again, the disinformation campaign was defeated, an international agreement was developed, and the ozone layer began recovering — though climate change threatens this recovery.

As the scientific consensus regarding climate change developed, many of the same skeptics — now funded by energy corporations — launched another campaign to discredit scientific consensus. Frank Luntz, a tactician in the 1994 Newt Gingrich Contract With America, recommended the blueprint: "The scientific debate is closing [against us] but not yet closed. There is still a window of opportunity to challenge the science. You need to be even more active in recruiting experts who are sympathetic to your view, and much more active in making them part of your message." While the dwindling number of skeptics are still waging their rearguard battle, fortunately international and U.S public opinion are rendering them irrelevant.

Contrary to the claims of some politicians and commentators, climate change is no longer a partisan issue — if ever it was. Republican presumptive presidential nominee John McCain has described it as a fact demanding our action and both Democratic candidates are committed to addressing it.

In 1988 the United Nations Environment Program and the World Meteorological Union established the Intergovernmental Panel on Climate Change. The IPCC — composed of thousands of atmospheric and climate scientists worldwide — monitor research on climate change, and provide summaries of the science regarding its impacts together with options for adaptation and mitigation ( It offers three conclusions:

1. "Warming of the climate system is unequivocal as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level."

2. "Most of the observed increase in globally averaged temperatures since the mid 20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."

3. "The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report [TAR 2001] leading to very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming."

Though the basic data render an unequivocal pattern, the IPCC does not claim certainty concerning its cause. Rather, conclusions are presented in terms of their probability: both 'very likely' and 'very high confidence' represent greater than a 90 percent level of certainty. Most of us, if advised by thousands of oncologists that there existed a 90 percent or greater probability that we had cancer, would accept the diagnosis and probably accept the recommended treatment.

Consensus in science develops slowly. The basic route is through publication: Reports of research are published in the scientific journals after being reviewed for accuracy in methods and conclusions by an editorial board and peer experts. When there is controversy regarding interpretations — as is sometimes the case — competing scientists conduct their own research, and publish their results in like manner. As a result of such exchanges in the literature, scientific experts in the field are able to read and evaluate the competing interpretations and draw conclusions. When such evaluations have been undertaken, and agreement develops among recognized experts consensus is achieved.

Consensus in science does not rely on what politicians or political commentators think or write based on preconceived notions of what they imagine reality should reveal. It is not developed from what novelists or Internet bloggers write, and it is not influenced by letters written to or opinions published in newspapers, magazines or by politicians.

The literature on climate change is clear and unequivocal; there is no longer debate. There is no corps of experts with contrary views whose manuscripts are being rejected or suppressed by a conspiracy of liberal climate scientists. The editor of one of the most prestigious scientific journals reported that the so-called skeptics are simply not submitting manuscripts. We can only conclude that this is because they have no credible research to support their skepticism.

Alan Journet of Cape Girardeau is co-facilitator of the Southeast Missouri Climate Protection Initiative and a professor in the Department of Biology and Environmental Science Program at Southeast Missouri State University.

Respond to this story

Posting a comment requires free registration: