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Press warns of global climate change

By Brian Rosenberg

The world climate could undergo severe changes over the next several decades, warned Frank Press, president of the National Academy of Sciences. But Frank warned against taking drastic measures -- such as economic restructuring and legislative carbon dioxide production limits -- in response because of the lack of scientific consensus on the subject.

Press, a member of the MIT Corporation and former head of what is now the Earth, Atmospheric, and Planetary Sciences Department, gave a lecture yesterday on global climate change. The lecture was the first of a series sponsored by the Technology and Culture Seminar which focuses on technology and the environment.

Press cited the results of four models developed by researchers he described as "a range of responsible people." He stated that by 2050, "most modelers agree that the atmosphere will warm to ... temperatures possibly higher than [at] any time in the past million years."

According to one model, global mean temperatures will increase between two and five degrees Celsius within five years. The same model predicts an increase in sea level between 10 centimeters and one meter within the next five to twenty years. These figures have a high degree of confidence, according to Press.

Local predictions were less accurate, with temperatures expected to fall in the range of three degrees less to ten degrees more than at present. Local precipitation could change up to twenty percent in either direction, and local soil moisture up to 50 percent.

These changes could cause effects as drastic as "a more severe and long-lasting drought ... than we experienced in the 1930's [the Dust Bowl]." One 1983 model, assuming a two percent increase in temperature and a ten percent decrease in precipitation over the western United States, predicted a 40 percent decline in runoff in the Colorado River basin. Sea ice levels are expected to decline, and changes in currents may disrupt marine fisheries.

"We're predicting a rate of change of temperature due to the greenhouse effect that is ten to fifty times greater than the natural change," Press said. "This raises the question," he continued, "of not just can species migrate, but can species survive?"

"The effect on human health should not be underestimated," Press said later. He stressed the uncertainty in climactic models due to the nonlinearity of the atmosphere, and expressed the various predictions in terms of "could be."

Because of this uncertainty, Press recommended a series of "tie-in" policies which would be beneficial even without the greenhouse effect. Examples of these policies included the elimination of chloroflourocarbons (CFC's) by the year 2000, reforestation, and population control. Press also advocated reduction of carbon dioxode production and water consumption through conservation and realistic pricing. "If we are to manage the global commons well," he stated, "we must treat planet Earth as a closed system."

Audience reaction to Press' lecture varied. EAPS Professor Richard Lindzen objected to Press' labeling of uncertainties as high or low. He considered the models Press used to be "very poor" and stated that they only gave correct numbers when "tuned ... [i.e.] modified ad hoc."

Thomas Jordan, EAPS department head, thought Press presented "very realistic" figures, but added that "models are nothing more than models."

Press himself said afterwards that his lecture "went well ... I was pleased that [the audience] wasn't bored."

Scott Paradise, an MIT religious counselor who works on the Technology and Culture Seminars, thought the lecture was "the national controversy writ small." He pointed out the "different perspectives from the audience" and thought the series had gotten off to a good start.

The next seminar, entitled "We Want It All," will be on Development and the Environment. Dr. Mustafa Tolba, director of the United Nations Environmental Program, will present the lecture on Oct. 17.