The Heat Is On

Chemical wastes spewed into the air threaten the earth's climate

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It is not yet clear whether ozone depletion in the Antarctic is an isolated phenomenon or whether it is an ominous warning signal of more slowly progressing ozone destruction worldwide. Data indicate that the decline over the past eight years is 4% to 5%. Scientists estimate that natural destruction of the ozone could account for 2% of that figure. The Antarctic hole could explain an additional 1%. The remaining 1% to 2% could simply be the result of normal fluctuations. As Albritton's research team reported, "A depletion of this magnitude would be very difficult to identify against the background of poorly understood natural variation."

The same can be said for the greenhouse effect: it is too soon to tell whether unusual global warming has indeed begun. Unlike ozone depletion, the greenhouse effect is a natural phenomenon with positive consequences. Without it, points out Climate Modeler Jeff Kiehl, of the National Center for Atmospheric Research, "the earth would be uninhabitable. It is what keeps us from being an ice-frozen planet like Mars." Indeed, if gases like CO2 did not trap the sun's energy, the earth's mean temperature would be 0 degrees F, rather than the current 59 degrees.

Still, as far back as the late 1890s, Swedish Chemist Svante Arrhenius had begun to fret that the massive burning of coal during the Industrial Revolution, which pumped unprecedented amounts of CO2 into the atmosphere, might be too much of a good thing. Arrhenius made the startling prediction that a doubling of atmospheric CO2 would eventually lead to a 9 degrees F warming of the globe. Conversely, he suggested, glacial periods might be caused by diminished levels of the gas. His contemporaries scoffed. Arrhenius, however, was exactly right. In his time, the CO2 concentration was about 280 to 290 parts per million -- just right for a moderately warm, interglacial period. But today the count stands at some 340 p.p.m. By 2050, if the present rate of burning fossil fuels continues, that concentration will double, trapping progressively more infrared radiation in the atmosphere.

The consequences could be daunting. Says National Center for Atmospheric Research's Francis Bretherton: "Suppose it's August in New York City. The temperature is 95 degrees; the humidity is 95%. The heat wave started on July 4 and will continue through Labor Day." While warmer temperatures might boost the fish catch in Alaska and lumber harvests in the Pacific Northwest, he says, the Great Plains could become a dust bowl; people would move north in search of food and jobs, and Canada might rival the Soviet Union as the world's most powerful nation. Bretherton admits that his scenario is speculative. But, he says, "the climate changes underlying it are consistent with what we believe may happen."

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