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TIME: Almanac 1993
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TIME Almanac 1993.iso
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012191
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1992-08-28
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ENVIRONMENT, Page 65Hot Times
A balmy 1990 may presage a dangerous climatic trend
Is global warming upon us? Many climate experts say it is
only a matter of time before heat trapped in the atmosphere by
man-made chemicals raises world temperatures, melting polar ice
caps, raising sea levels and generally wreaking havoc. Most
also go on to caution that it is too soon to declare that the
warming has begun. But two studies released last week evoked
concern that a shift is already under way. Teams of scientists
in the U.S. and Britain found that 1990 was the warmest year
in more than a century of record keeping. The average worldwide
temperature, said the Americans, was 15.5 degrees C (59.8
degrees F), while the British, using a different set of
readings, pegged it at 15.4 degrees C (59.7 degrees F).
One hot year does not make a trend, since temperatures
naturally vary from year to year. But the Americans, at NASA's
Goddard Institute for Space Studies, pointed out that the new
data mean that the seven warmest years since 1880 have all
occurred in the past 11 years. On average, the 1980s were about
.6 degrees C (1 degrees F) warmer than the 1880s, while 1990
was .7 degrees C (1.25 degrees F) warmer. That may not sound
like much, but a mere 5 degrees C (9 degrees F) rise was enough
to bring the earth out of the last ice age.
If global-warming theorists are correct, temperatures could
rise by another 1 degrees to 4 degrees C (2 degrees to 8
degrees F) over the next half-century. Unfortunately, no one
can say whether even a decade-long heat wave confirms this view
or is merely a glitch. Worse, says Stephen Schneider of the
National Center for Atmospheric Research: "By the time the
evidence is irrefutable, it could be too late to do anything."