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GCC History
12/24/2002
Listen in RealAudio 
Ice cores, collected from cold places such as Greenland and Antarctica, have yielded clues to
change from about 100,000 years ago to the present. Now, another type of coring from the
Pacific Ocean floor is giving scientists a peek at global climate change 50 million years ago.
Hi, I'm Bryan Yeaton for The Weather Notebook. Jeff Rice tells us what they found.
Imagine alligators roaming as far north as the Arctic. That's a snapshot of
the earth as it was 50 million years ago, during the tropical Eocene. It was
a time without polar ice caps, and it's of great interest to scientists
studying current trends in global warming. Dr. Mitch Lyle is a paleooceanographer at Boise
State University. He was one of the chief scientists on a recent drilling expedition in the
Pacific Ocean, which looked for climate clues in the fossil record.
ML: One of the lucky things about the ocean is... the plankton are very attuned
to the physical conditions, the temperature and salinity of the water. So
you can take a remains of these organisms and reconstruct temperature...
things on this order.
Soil samples from beneath the ocean floor paint the clearest picture yet of
the Eocene climate, crucial for creating scientific models.
ML: We have a lot more confidence in terms of being able to predict a few degree temperature
change that may result from the CO2 we're now adding.
Though it began at a higher mean temperature, the Eocene experienced a rapid
period of global warming similar to the one the Earth faces today. It was
believed to be caused by massive releases of methane, which caused a
build-up of greenhouse gasses. In that case, it took about 100,000 years for
the Earth to recover and return to normal.
Our 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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