Down from the ivory tower: climate science faces the real world.

Abstract

It would be an overstatement to suggest that the science of Earth’s climate system has led a sheltered life. For one thing, it has grown out of a long history of public service (e.g., weather forecasting for the public and private sectors; oceanography and marine meteorology for naval applications). For another, public interest in climatic events — ice ages, nuclear winter, El Nino, sea-level change — is sufficiently high that climate is nearly continuously in the news and has been for years. However, compared to many other branches of science — biomedicine and nuclear physics come to mind — the community of scientists who investigate the workings of Earth’s climate has tended to avoid the spotlight. They did this with fair success until recently, when global warming came along. Now, they are thrust into the glare of public scrutiny due to the controversy over projections of the rise of global temperatures associated with increases of carbon dioxide and other greenhouse gases in the atmosphere. Earth’s climate is an extraordinarily complicated physical, chemical, and biological system. Simulating its behavior is both challenging and fraught with uncertainty due to chaotic processes within the climate system itself and lack of knowledge about future atmospheric composition as well as both known and unknown deficiencies in the computer models used for the simulations. When public scrutiny becomes part of the equation, matters become even more complicated, because explaining the complexities of the climate’s behavior to the lay public is a challenge unto itself. Unfortunately, this challenge is not always met successfully. For example, there is widespread, interchangeable use of the terms “greenhouse effect” and “global warming,” an error that introduces only confusion into the ongoing discussion. It is perhaps worthwhile to emphasize the difference between the two here. What we call, with some imprecision, the greenhouse effect is a climate system process, in which gases in Earth’s atmosphere absorb and re-radiate the heat given off by Earth’s surface and by the atmosphere itself. The net effect of this is to insulate the planet and to keep the place livable. Without our atmosphere, Earth’s average temperature would be around –18oC (0oF) rather than the balmy 15oC (59oF) or so that we enjoy today. The greenhouse effect is as real as gravity and, in many respects, more well understood at the quantum level. Global warming, on the other hand, is one possible result of the net effect of all climate system processes when the system is perturbed somehow. The perturbation of concern just now,