Earth's Temperature At Highest Level In 12,000 Years
Climate may soon be as warm as it was 1 million years ago
Bette Hileman
Earth's temperature has climbed to a level not seen for 12,000 years,
warns a new study published online in Proceedings of the National
Academy of Sciences (DOI: 10.1073/pnas.0606291103).
The research, led by James E. Hansen, head of NASA's Goddard
Institute for Space Studies, finds that the mean surface temperature
of the planet has been warming at a rate of 0.2 ¬ƒC per decade for
the past 30 years. The global mean temperature is now within 1 degree
C of the maximum for the past million years, the study concludes.
"This evidence implies that we are getting close to dangerous levels
of human-made pollution," Hansen says. If additional warming is kept
lower than 1 degree C, "the effects of global warming may be
relatively manageable. But if further warming reaches 2 to 3 degrees
C, we will likely see changes that make Earth a different planet than
the one we know." The last time Earth was this warm was about 3
million years ago when sea level was about 25 meters higher than
today, he explains. If CO2 emissions are not curbed, global
temperatures are likely to rise 2 to 3 degrees C by 2100, he warns.
Hansen collaborated with David W. Lea and Martin Medina-Elizade of
the University of California, Santa Barbara, to compare recent
temperatures with temperatures derived from sea sediments deposited
over the past million years.
The study explains that global warming is already affecting species.
Research has found that 1,700 plant and animal species are moving
toward the North or South Poles at a rate of 6 km per decade, but
over the past 30 years, climate zones have been moving poleward at a
rate of 40 km per decade, Hansen says.
Chemical & Engineering News
ISSN 0009-2347
Copyright © 2006 American Chemical Society
Posted on Yahoo Group ClimateChange
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