Interesting article, suggests that the sea level changes could happen much sooner than thought. From todays Toronto Star
Greenland glaciers `sending us a signal'
Massive melting `floors' scientists Will become major research focus
Feb. 17, 2006. 05:35 AM
PETER CALAMAI
SCIENCE REPORTER
ST. LOUIS—Global warming is propelling Greenland's glaciers off the land in a lemming-like rush and dumping nearly twice as much ice into the Atlantic Ocean as five years ago, a NASA scientist said yesterday.
The glacier surge, unknown until it was discovered by a Canadian radar satellite, means sea levels worldwide are rising much faster than predicted.
"These results absolutely floored us," said Eric Rignot, of NASA's Jet Propulsion Laboratory in Pasadena.
"The glaciers are sending us a signal."
Every year, Greenland is adding enough water to the ocean to supply the needs of 200 cities the size of Los Angeles, Rignot told reporters yesterday at a science conference here.
The surging glaciers account for two-thirds of this flood and surface melting makes up the rest, according to calculations made by Rignot and co-author Pannir Kanagaratnam and published in today's issue of Science, the journal of the American Association for the Advancement of Science.
The ice chunks alone shed by Greenland in one recent year would make a square pillar six kilometres high and five kilometres wide on each side.
The researchers calculate that Greenland's contribution to rising sea levels worldwide has more than doubled since 1996, and reached almost 0.6 millimetres in 2005. Total sea-level rise globally is about 3 millimetres a year.
This phenomenon of surging glaciers dumping vast amounts of ice is certain to become a major research focus for the hundreds of scientists who will blanket the Arctic and Antarctic when International Polar Year kicks off in 2007.
The findings will also spur climate modellers to revise their projections of the sea-level rise blamed on global warming.
The Greenland ice cap, which is as vast as Mexico and up to three kilometres thick, would raise sea levels by seven metres if it melted completely.
"This shows the importance of monitoring the world's ice sheets better than we've been doing in the past," said Gordon McBean, a Canadian climate expert deeply involved in Arctic studies and a professor at the University of Western Ontario.
Rignot and Kanagaratnam discovered the acceleration in the seaward flow of scores of glaciers by comparing the speed of ice movement in 1996, 2000 and 2005.
The Kangerdlugssuag glacier in southeastern Greenland quadrupled its speed in 2000 to hit 14 kilometres a year.
Most of the speed measurements were made by Radarsat-1, a Canadian earth observation satellite that has been orbiting at an altitude of 800 kilometres for the past 10 years.
"Radarsat was the centerpiece that really made this discovery possible," Rignot said in an interview.
The satellite's advanced radar beam can see at night and penetrate clouds and rain, making possible the complete mapping of Greenland in a minimum number of orbits.
The glacier surge has been most noticeable in southeastern Greenland, where average air temperatures have soared by 3C over the past two decades.
But Rignot added that the most recent measurements reveal that glaciers farther north are also increasing their flow speeds as temperatures rise there as well.
Warmer temperatures increase the amount of melt water percolating through a glacier to the rocks below, where it lubricates the ice flow and speeds the glacier's march to the sea.
Roy ("Fritz") Koerner, considered he dean of Canada's glaciologists, said warmer summers are also speeding up glacier flow on Devon Island in the Arctic, where he's carried out research for four decades.
"There's more melt water around and therefore a longer period of time for the glaciers to move," Koerner said in a telephone interview from Ottawa.
"There are going to be lots more surprises."