Climate Science Uncertainties Still Cloud Kyoto

Published January 1, 1998

Throughout the seemingly endless series of speeches and closed-door negotiating sessions at the recently concluded Kyoto conference on global warming, there was one word delegates wouldn’t touch with a ten-foot pole: science.

About the only time the word was mentioned was in the almost ritualistic statements to the effect that “there is a scientific consensus that global warming is real.” Those giving such assurances were, for the most part, political appointees and high-level bureaucrats well aware of the price to be paid for uttering the “s” word.

Science may have been checked at the door in Kyoto, but the subject refuses to go quietly. Less than six months before the Kyoto conference got underway, Science magazine reported that climate modelers were having grave misgivings about their vaunted computers’ ability to predict global temperatures with the accuracy they once thought possible. A few months later, The New York Times revealed that long-observed fluctuations in the world’s climate may have more to do with irregularities in solar radiation than with anything humans are doing on Earth.

None of this can be comforting to those intent on closing the debate over whether global warming is a human-induced problem so they can get on with the solution. A recently released paper by the Washington-based George C. Marshall Institute shows why nagging scientific questions will continue to be raised.

Authors Sallie Baliunas and Willie Soon, both of the Harvard-Smithsonian Center for Astrophysics, observe that “calculating the response of the climate to causes is extremely difficult because the climate is a nonlinear, coupled, dynamical system.”

“It is essential to remember the distinction between the input of energy to the climate system (through, e.g., an increase in greenhouse gases) and the much harder task of calculating its climatic response,” they continue. “The difficulty in calculating the climate response is reflected by the fact that current climate simulations fail to meet the criterion of validation. Only further research promises to allow the computer simulations to compare accurately human and natural causes of climate change.”

To illustrate their point, Baliunas and Soon comment on recent statements by Michael MacCracken of the Office of the United States Global Change Research Program, issued under the title “The Truth About Ten Leading Myths.” Baliunas and Soon allow MacCracken to speak for himself and then provide scientific background information that casts doubt on the accuracy of his statements.

MacCracken, for example, states that, “Most climate scientists agree that the climate is changing and will change much more, causing a wide range of environmental and socio-economic consequences.” Baliunas and Soon respond by observing that, “An important property of climate is variability. The issue is whether the human effect on climate is, or will shortly become, significant against this background of natural variability. Answering this question requires that the underlying natural variations of climate be understood, so that human impact may be distinguished quantitatively from natural variability.”

Confronting MacCracken’s view, widely held among global warming proponents, that climate change will cause a “wide range of environmental and socio-economic consequences,” Baliunas and Soon cite the United Nation’s Intergovernmental Panel of Climate Change (IPCC). The IPCC reported in 1995 that, “Overall, there is no evidence that extreme weather events or climate variability has increased, in a global sense, through the 20th century.”

“This lack of increasing climate variability occurred during the period when greenhouse gases in the atmosphere are estimated to have increased by an amount equivalent to a 50 percent increase in carbon dioxide alone,” Baliunas and Soon point out. “In addition, the climate models do not give reliable predictions on the matter as evidenced by the fact that the models predict too little climate change on timescales of decades to centuries when compared with the actual change that has been observed.”