Climate Change

From: Benny J Peiser <[email protected]
To: [email protected] <[email protected]
Date: 30. januar 1998 16:47
Subject: CC DIGEST, 29/01/98

New Evidence for Major Punctuation of Global Climate at the Pleistocene / Holocene Boundary
From: Clark Whelton <[email protected]>
The New York Times Science Section, January 27, 1998
If Climate Changes, It May Change Quickly.
William K. Stevens

"...A growing accumulation of geological evidence is making it ever clearer that in the past the climate has undergone drastic changes in temperature and rainfall patterns in the space of a human lifetime, in a decade or in even less time."

"....In uncovering one of the latest pieces of evidence of abrupt climate change, American scientists led by Dr. Jeffrey P. Severinghaus of the University of Rhode Island examined climatic clues taken from corings of ancient ice in Greenland. "

The Severinghaus team determined that when the world began its final ascent out of the last ice age more than 11,000 years ago, temperatures in Greenland initially spiked upward by about 9 to 18 degrees F. -- at least a third, and perhaps more, of the total recovery to today's warmth -- in, at most, mere decades and probably less than a single decade. They also found that the impact of the sudden warming had been felt at least throughout the Northern Hemisphere. "That amount of heating, coming so quickly, is astounding," said Dr. Richard Alley of Pennsylvania State University, a member of the study team. Another recent study, by Dr. Peter deMenocal, a paleoclimatologist at Lamont-Doherty, examined clues in Atlantic Ocean sediments off sub-tropical North Africa. He discovered that every 1,500 years or so since the end of the ice age, ocean temperatures there have fluctuated wildly and abruptly. "In a cold phase, they fell by 5 to 15 degrees, and seasonal rains on the continent were severely curtailed -- all within no more than 50 to 100 years, and possibly less (the sediment analysis is not fine enough to tell). Then, in another 1,500 years, the picture reversed just as abruptly, causing flooding rains and creating widespread lakes in what is now theSahara.

"The transitions are sharp," Dr. deMenocal said. "Climate changes we thought should take thousands of years to happen occur within a generation or two," at most. The changes may have wreaked havoc on nascent civilizations in Africa and the Middle East. "It was certainly something that would have rocked somebody's world," Dr. deMenocal said.