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E-M:/ Michigan scientist heads study on global climate change



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Enviro-Mich message from Dave Dempsey <davemec@voyager.net>
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Rocks Tell Tale Of Warming Earth

WASHINGTON (Reuters) - The Earth has warmed nearly 2 degrees Fahrenheit in
the past 500 years -- half of it in this century alone, scientists reported
Friday.

They said holes drilled in the ground all around the planet confirm that
this has been the warmest century on record.

The secret to their analysis is the geothermal record. Rock and soil
literally remembers past temperatures, Henry Pollack of the University of
Michigan at Ann Arbor and colleagues at the University of Western Ontario
reported in the journal Science.

``Analyses of underground temperature measurements from 358 boreholes in
eastern North America, central Europe, southern Africa and Australia
indicate that the 20th century has been the warmest of the past five
centuries,'' they wrote.

They said the boreholes, 600 feet to 1,800 feet deep, showed a clear record.

``Temperature changes in the Earth's surface propagate slowly downward into
the rocks beneath the surface,'' they wrote. ``Thus, present-day subsurface
temperatures provide evidence of temperature changes that have occurred at
the surface in the past.''

Pollack's team did not drill the holes themselves but took the measurements
from a project by the International
Association of Seismology and Physics.

They found 80 percent of the sites showed evidence of the warming over 500
years. But the past 100 years have been the warmest.

``The temperature of the 20th century appears to be warmer than the mean
temperature of any of the previous four centuries,'' they wrote.

The evidence supports observations taken from tree rings, cores drilled
into the ice of glaciers, and historical written records. 


Dave Dempsey
Policy Director
Michigan Environmental Council
119 Pere Marquette, Suite 2A
Lansing, MI 48912
davemec@voyager.net
www.mienv.org

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