Cooling Off on Global Warming

June 29, 1994|BY S. FRED SINGER

WASHINGTON — It's been a chilly spring, at least in the United States and Europe, and global warming seems far away. Nevertheless, governments have been gearing up to carry out the mandates of the Global Climate Treaty, trying to throttle the use of energy.

The threat of a temperature rise of a couple of degrees Celsius -- if indeed it is a threat -- is based entirely on rather complicated calculations from a rather simple theory, namely that a build-up of carbon dioxide (CO2) in the atmosphere from the burning of oil, gas and coal, will, like a blanket, retain more of the earth's heat, resulting in a warmer climate.

The theory has not been proved by direct observations. The global temperature record of the past 100 years does show a small increase, about 0.5 degree C (0.9 degree Fahrenheit), but that is less than half of what is predicted. Worse still -- for the theory -- the increase occurred before 1940, well before there was a substantial build-up of CO2. Why then believe predictions for a future warming catastrophe?

When the treaty was adopted at the Rio de Janeiro ''Earth Summit'' in June 1992, it was with the understanding that the greenhouse theory was ''broadly consistent' with the observations -- and that therefore the theory would be relied upon as a basis for policy. But this is not the case.

The ''official'' global record, supplied by the U.N.-sponsored intergovernmental Panel on Climate Change, shows maximum temperatures in the 1980s and still rising ominously.

By contrast, the published analysis of the U.S. temperature record by the climatologist Thomas Karl and colleagues at the National Oceanographic and Atmospheric Administration shows a maximum around 1940, followed by a decrease. Dr. Karl's analysis is based on carefully selected weather stations and the elimination of the ''heat island'' effect, the warming caused by urban sprawl. His work was discounted, however, because it applied only to a small portion of the earth's surface.

A new analysis by Wisconsin climatologist Reid Bryson, published in the winter, 1993, issue of Environmental Conservation, questions anew the intergovernmental panel's conclusions. Dr. Bryson combined a predominantly land-station record with what he considers to be the least biased record of the large array of ships' observations. His result also shows a global temperature maximum around 1940, generally confirming Dr. Karl and, of course, in contradiction to the intergovernmental panel.

The highest-quality data now come from a satellite-borne

microwave radiometer, which measures the temperature of the lowest layer of the atmosphere as it orbits the globe from pole to pole. Admittedly, the satellite record is still brief -- just 15 years -- but the precision is excellent. While the mathematical models predict a ''best'' temperature rise of 0.3 degree (0.5 degree Fahrenheit) per decade, the satellite data admit, at most, one-fifth of that. If extrapolated to the next century, the feared global warming may not even be detectable above the ''noise'' of natural climate fluctuations.

So it's back to the drawing board for the greenhouse theory. Experts agree that the mathematical models do not simulate the atmosphere well enough. The treatment of clouds is one area that needs much improvement. Scientists may well discover that additional greenhouse warming of the ocean creates more evaporation, and therefore more cloudiness, which in turn reduces the amount of solar energy reaching the earth's surface -- a classic case of a ''negative feedback.''

But the fact that science now offers scant support to the global-warming scare has not slowed the politicians, nor forced a revision of the Climate Treaty.

S. Fred Singer, a geophysicist, directs the Science & Environmental Policy Project of the Alexis de Tocqueville Institute.

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