And the heat goes on...
One of the great difficulties in testing theories of global warming is doing conclusive experiments. For example, having but one world, it is not possible to manipulate greenhouse gases in the atmosphere while also observing the climate of an unmanipulated experimental control. Thus, there are inherent limitations on knowledge obtainable by experimentation, and computer models have been developed to help us understand the interactions of the various phenomena that determine global climate.
Problems should be expected now that these models have become tools, not so much for understanding, but for making predictions. Trying to explain away why the models say we should have experienced much more warming than has actually materialized, Wallace C. Broecker (Winter 1996) and other scientists contend that man-made warming has been offset by a natural cooling or by a cooling effect of aerosol pollution.
The validity of this explanation is difficult to assess because the theories of global cooling are as untestable as the theories of global warming. The antennae of healthy skeptics should shoot up when hearing untestable excuses, which tend to sound like new bogus theories invented to explain why the old bogus theory doesn't seem to work.
Nature remains unmoved by the popular theories of the day. Allan Mazur (Winter 1996) misunderstands science when he suggests that science should be done by consensus, for scientific truth, to the extent that we can find it, ought not be determined by vote. The findings of one scientist backed by sound experimental results are more reliable than the contrary opinions of 999 others who lack such results.
Neither should scientific truth be sought by appeal to authority. In a scientific debate, whenever you hear statements like, "Broecker says so and so," or "Michaels says such and such," this should be a signal to discount them.
Scientific understanding, to be sound, must instead be advanced by appeal to experimental and observational evidence. This, and not intelligent scientists or logical thought, is the unique characteristic that distinguishes science from other ways of knowing. Sound scientific argument should be advanced by statements that begin, "Smith's experiment with controls showed...." With so little solid experimental evidence behind global warming and the political and economic stakes so high, major deceptions are occurring (see Frederick Seitz, "A Major Deception on 'Global Warming,'" Wall Street Journal, June 12, 1996, p. A16).
Asimov's popular guides to science recount dozens of instances where the vast majority of scientists and the leading authority figures have been wrong. With the global warming debate sustained largely by science done by vote and appeal to authority, future Asimovs could have a lot to write about.
Walter L. Warnick, Ph.D.
U.S. Department of Energy
The views expressed are those of the author and do not necessarily reflect the views of the Department of Energy.
Professor Mazur replies:
Walter Warnick misunderstands science when he suggests that scientific truth is based exclusively on "sound experimental results." In the first place, major fields of science--astronomy, geology, evolutionary biology--make little use of experiments. In the second place, when two "sound experiment results" contradict each other, as they often do, how does the scientific community decide which one is "really sound" except through consensus formation? In the third place, every "sound observation" permits multiple theoretical interpretations, so how is the "One True Interpretation" reached if not by debate among scientists until they reach consensus?
Maxwell School of Citizenship and Public Affairs