DEAR SIR

During my recent visit to Australia I noticed that here as in North America global warming is very much a hot topic. In both hemispheres a veritable industry spews forth opinions about the consequences of global warming on everything under the sun. No doubt at this very moment a group in Australia funded by Qantas is assessing the consequences of global warming on the flavour of Long flat Red. Until recently, global warming produced by increased carbon dioxide as a result of burning fossil fuels occupied the same position in the minds of meteorologists as tenets in the Apostle's Creed do to devout Catholics. To question global warming was unthinkable. More than heresy, it was folly. But there are always brave souls willing to risk throwing dead cats into temples, and at last a few dissidents have appeared on the scene. Prominent among them is Richard Lindzen (see, e.g., BAMOS, April 1993). He may be wrong but he is too knowledgeable to be dismissed as an ignoramus or a crank. A healthy debate on global warming, long lacking, has begun to emerge, although the balance is still heavily in favour of true believers. One aspect of the global warming debate that has to my knowledge never been aired has a psychological flavour. One of meteorology's dark secrets is that meteorologists suffer from an inferiority complex, which a Freudian psychologist might label physics envy. Like it or not, meteorologists have not been held in especially high esteem. They are frequently the butt of humiliating jibes about the inexactness of their science and about their alleged inability to predict the weather. Although those who make these jibes are on all fours with know-nothings who assert that physicians cannot heal us (they can heal us, they just cannot grant us immortality), even unjust barbs can sting.

But all this has changed recently. Meteorologists have been propelled into the limelight, transformed from ugly ducklings into swans. Drunk on the wine of public favour, meteorologists are hiring press agents, buying blow dryers, and trading in old spouses for new. Meteorologists are sought as guests on talk shows, courted by the press, invited to dine at the homes of presidents and prime ministers and the palaces of archbishops. Politicians now listen intently to the pronouncements of meteorologists, whereas not long ago their opinions would have evoked at best a yawn, more likely contempt. And by great good fortune this transformation has occurred just as physics has gone into decline. For many years following World War II physicists were caught up on a wave generated by the bombing of Nagasaki and Hiroshima. For almost half a century physicists have been the beneficiaries, consciously or not, of fear of The Bomb. Give us more money, they have said, or our ability to obliterate the Russians will fall behind their ability to obliterate us. Of course, all physicists do not work on bombs, but all boats do rise on a rising tide. With the sudden and unpredicted collapse of The Evil Empire, the bomb factories are shutting down and, not by coincidence, physics is in decline. Conservation of fear demands a new bogeyman. Fortunately, just in time, Global Warming has emerged to fill the gap, and meteorologists have been quick to exploit it. Meteorologists are at the same time those best able to pronounce on global warming and those whose assertions should be treated with the most caution. It is not that global warming is not true but rather that it is too good not to be true. It has rescued meteorologists from oblivion, increased their stature, even fattened their purses. Because meteorologists are knowledgeable but not disinterested, they should be listened to but not necessarily believed. I, for one, believe little what climate modellers say. My scepticism is based partly on linguistic grounds.

Climate modellers almost without exception refer to their computer simulations as "experiments', rarely even qualified by "numerical." What's in a word?, you may ask. Words betray inner states of mind, and the words used by modellers indicate to me that they have crossed the line between reality and fantasy. To them, their computer simulations really are experiments on the same footing as the kind in which experimenters get their hands dirty. Modellers discuss the results of their (numerical) experiments in the same way that laboratory scientists discuss theirs. Yet a simulated "experiment' according to Robert Romer (American Journal of Physics, Vol. 61, 1993, p. 128) is "the creation of the devil, and the temptation to use one must be stoutly resisted." I also am sceptical of climate modellers because of their habit of dismissing as inconsequential everything their models cannot treat. Not long ago, clouds were considered to be minor players in the global warming drama. Why? Because modellers couldn't adequately include clouds in their models. Or because modellers are heavily steeped in dynamics, and clouds occupy a low status in the various kingdoms and duchies into which the atmosphere has been artificially divided. My scepticism about climate models is fuelled by their inability to postdict the climate.

To my knowledge, no model run backward in time from the present has predicted the observed temperature decrease that not so long ago was generating alarms about global cooling. It has long been accepted that to acquire validity, a theory must have predictive capabilities. What are we to make of a theory that doesn't even have postdictive capabilities? True, rather than simulated, experiments will provide the evidence for or against global warming just as true, as opposed to simulated, sex is what makes babies.

Craig F. Bohren Department of Meteorology The Pennsylvania State University (circa 1993) AMOS Bulletin #6 82