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>Saturday, April 28, 2001
>CO2 HISTORY MYSTERY
>Scientists digging into the geologic record find a puzzling discrepancy
>between carbon dioxide concentration and expected world climate. More --
>after this on Earth and Sky.
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>
>JB: This is Earth and Sky, on the complexity of world climate. Dr. Mike
>Arthur is a geologist at Penn State University. He's helped examine
>deep-sea drill cores to try to track our planet's history in terms of
>carbon dioxide . . .
>
>(Mike Arthur): One of the signals we thought we would see as we go into
>the major glacial epoch, about 14 million years ago, that there would be a
>big drop in carbon dioxide concentration in the atmosphere.
>
>JB: It's well known that carbon dioxide in the atmosphere can trap heat
>near Earth's surface. So, going into an ice age, you'd expect to see less
>of it. But the team measured an increase in carbon dioxide as Earth slid
>into the last ice age. Digging farther back in time, they found that 20
>million years ago Earth was warmer than it is today -- yet it had only as
>much carbon dioxide as today -- or even a bit less. The lesson here?
>World climate is complex . . .
>
>(Mike Arthur): You know, geologists, we like to find single explanations.
>. . But as we all really know, the Earth is much more complicated, and
>there are probably a variety of forces that come into play to produce these
>events.
>
>JB: Dr. Arthur added that, although the climate is complex, it's clear to
>him and many other scientists that CO2 increase today is leading to global
>warming. Special thanks today to NASA's Earth Science Enterprise. I'm
>Joel Block for Earth and Sky.
>
>http://www.earthsky.com/2001/es010428.html
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