EDITOR'S PAGE
Global warming t is hard to imagine a topic of more intrinsic fascination to the scientific community than global warming. Chemistry is central to understanding any role of the so-called greenhouse gases in climate change, especially in recent and possible future temperature increases. But such understanding also depends on inputs from every other scientific discipline. If ever there was a subject demanding a multidisciplinary approach, it is global warming. It seems to involve everything from the subtleties of millisecond chemical reactions to, literally speaking, glacial changes. In this issue of C&EN (page 7) is an article by senior editor Bette Hileman on the status of the science of global warming. It emphasizes new data and insights that have evolved in the three years since her previous major report on the topic (C&EN, March 13,1989, page 25). As Hileman reports, much has been learned since 1989 about the multiple feedbacks of the climate system. She adds, however, that "Surprisingly, even though the system now seems more complex, scientists feel closer to, not further from, a comprehensive understanding of how the various components interact/' Despite the complexities and uncertainties, there are three essentially undisputed facts: • The world has warmed by from 0.3 to 0.6 °C over the past century. It doesn't sound like much of a change until one realizes that over the past 10,000 years average global temperature has never been more than about 1 °C warmer or cooler than it is today. • The concentration of carbon dioxide, the principal greenhouse gas in the atmosphere, has risen from about 280 ppm to 356 ppm over the same century. • The bulk of this 27% carbon dioxide increase has been due to human activity, mainly the burning of fossil fuels. As scientists know, such data do not necessarily indicate a cause-and-effect relationship. As suggestive as they are, they do not prove that human activity exacerbates global warming and so could cause disruptive climate change in the future. As some scientists point out, there were global temperature swings in much earlier times when human activity could not have been a factor. Others suggest that the current warming trend is natural, a continuation of the recovery from the "Little Ice Age" that started about 500 years ago. Yet others suggest that some as yet poorly understood factors, such as the role of clouds and the oceans, could cancel out temperature gains projected primarily on the basis of increasing greenhouse gas concentrations. Politically, global warming has become highly contentious. One camp demands immediate curbs on carbon dioxide emissions. Another insists on waiting for clearer scientific understanding before making such a major move. However, in the long run the handling of the threat of global warming may turn out to increase the common ground between what can best be described as traditional business interests and the environmental, or green, movement. These parties will always have major differences. But their views appear to be gradually converging, not diverging. Both are now calling, in their own ways, for a better life for human society based on a sustainable economy built on the efficient and environmentally friendly use of resources. In the case of global warming, both sides are looking to science for guidance—even as they disagree about how much science is needed before taking action. In deciding what to do about global warming, the certainty that the concentration of carbon dioxide in the atmosphere will continue to increase for a generation or more, even if emissions curbs were initiated today, would suggest that prudence be given due consideration. Michael Heylin Editor
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Views expressed on this page are those of the author only and not necessarily those of ACS
APRIL 27,1992 C&EN
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