By Shankar Vedantam
Washington Post Staff Writer
Friday, February 17, 2006
Greenland's glaciers are melting into the sea twice as fast as previously believed, the result of a warming trend that renders obsolete predictions of how quickly Earth's oceans will rise over the next century, scientists said yesterday.
The new data come from satellite imagery and give fresh urgency to worries about the role of human activity in global warming. The Greenland data are mirrored by findings from Bolivia to the Himalayas, scientists said, noting that rising sea levels threaten widespread flooding and severe storm damage in low-lying areas worldwide.
The scientists said they do not yet understand the precise mechanism causing glaciers to flow and melt more rapidly, but they said the changes in Greenland were unambiguous -- and accelerating: In 1996, the amount of water produced by melting ice in Greenland was about 90 times the amount consumed by Los Angeles in a year. Last year, the melted ice amounted to 225 times the volume of water that city uses annually.
"We are witnessing enormous changes, and it will take some time before we understand how it happened, although it is clearly a result of warming around the glaciers," said Eric Rignot, a scientist at the California Institute of Technology's Jet Propulsion Laboratory.
. . .
The ice sheets in Greenland and Antarctica are among the largest reservoirs of fresh water on Earth, and their fate is expected to be a major factor in determining how much the oceans will rise. Rignot and University of Kansas scientist Pannir Kanagaratnam, who published their findings yesterday in the journal Science, declined to guess how much the faster melting would raise sea levels but said current estimates of around 20 inches over the next century are probably too low.
While sea-level increases of a few feet may not sound like very much, they could have profound consequences on flood-prone countries such as Bangladesh and trigger severe weather around the world.
"The implications are global," said Julian Dowdeswell, a glacier expert at the University of Cambridge in England who reviewed the new paper for Science. "We are not talking about walking along the sea front on a nice summer day, we are talking of the worst storm settings, the biggest storm surges . . . you are upping the probability major storms will take place."
Thursday, February 16, 2006
By Shankar Vedantam