We know two things about global warming. One: in the last 100 years the average temperature has risen between two-thirds and one degree Fahrenheit. Two: in the same time the amount of carbon dioxide and other heat-trapping gases in the atmosphere has risen about 40 percent.
That may not seem like a lot–Halsted is often that much warmer than the lakefront–but remember it’s an average, and the average temperature during the most recent ice age was only nine degrees cooler than today. The difference, global-warming activists point out, is that living things had thousands of years to adjust to that nine-degree warm-up following the ice age; we may have less than a century to adapt if the models’ high-end predictions are right.
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Changnon hasn’t written a book, but climatologist Robert Balling Jr. of Arizona State University has. In The Heated Debate: Greenhouse Predictions Versus Climate Reality, published by the libertarian/conservative Pacific Research Institute, he explains lucidly the weaknesses of the models and then offers his own best prediction:
I asked Changnon about Balling’s credentials, since his book, like Revkin’s and Schneider’s before him, is published by an interested party. “Bob Balling is doing science,” he said flatly. “Schneider is selling books.”
“The models are all tested on today’s weather,” cautions climatologist Changnon. “The public needs to understand the difficulty of determining how many of these factors–volcanic activity, clouds, atmospheric radiation, ocean storage–are going to stay the same.” Some model builders, he says, worry that environmentalists have gotten too alarmist with what are still fairly crude simulations of the real thing.
Some believe that journalism’s traditional preoccupation with politics ill equips journalists to cover the subject of global warming. Journalists insist on looking for “both sides,” inadvertently focusing on details being debated, polarizing issues, and obscuring what may be a broad agreement on basics. Revkin, a journalist himself, objects that this evenhandedness “confuses and paralyzes the reader.”
This line of argument, however, is also open to criticism from those who remember other looming problems that quit looming once scientists took a close look. In his book Revkin maintains a discreet silence on acid rain, which many once believed would make thousands of lakes ten times more acidic in just ten years. Balling fills in the blank: “After 10 years of study, the involvement of over 2,000 scientists, and an expenditure of over $500 million, the [federally funded] NAPAP [National Acid Precipitation Assessment Program] conclusion was that an acid rain problem exists, but it is not as serious or urgent as many had feared.” Acidification is proceeding at most only one-fourth as fast as feared, and in fewer lakes; NAPAP’s director told the New York Times early in 1990 that acid rain was no longer a top-priority environmental issue.
