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Mud
12/17/2002
Listen in RealAudio 
Hi, I'm Bryan Yeaton and this is The Weather Notebook's weekly segment on global climate
change. How do scientists figure out climate from years ago? Fifty million years ago, to be
exact? As Jeff Rice reports today, they dig deep into the ocean bottom.
In the Kevin Costner movie, "Waterworld," Hollywood creates a nightmare vision
of a time when the polar ice caps have melted and most of the earth is
covered in water.
Well, minus the raiding hordes of pirates, those are pretty much the
conditions that paleooceanographers observed on a recent expedition in the
pacific. Scientists drilled into the ocean floor to look at the climate
record of the Eocene, a time 50 million years ago, when there were
oceanfront palm trees in Wyoming.
ML: It's an important other world to look at. The Eocene is the youngest period
where we did not have ice at either pole.
Dr. Mitch Lyle of Boise State University was co-chief scientist during the
expedition. The ocean mud contains a sort of fossil record of the weather.
Dust sediment can reveal ancient wind patterns and even wind strength based
on dust size. Lyle's group was especially interested in studying the
fossilized plankton.
ML: Ocean plankton is very sensitive to what you call primary physical factors, the salinity,
and the temperature.
This can tell scientists how ocean currents moved based on the interactions
between cool and warm water. It's important because ocean currents are the
engines that drive worldwide weather. Lyle found that the currents during
the Eocene were fundamentally different from today because of the lack of
polar ice caps. Scientists can use this information to model current
conditions as polar ice caps recede.
Jeff Rice reports from Boise, Idaho. This special series on global climate change is
supported by the New England Science Center Collaborative and the Roy A. Hunt Foundation.
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