August 14, 2009

Giant Antarctic Glacier Melting At An Alarming Rate

Experts say one of the largest glaciers in Antarctica is thinning four times faster than it was 10 years ago, BBC News reported.

The surface of the ice at the Pine Island glacier in west Antarctica is now dropping at a rate of up to 50 feet a year, according to a recent study of satellite measurements.

The work, by British scientists and published in Geophysical Research Letters, shows that the glacier has lowered by almost 300 feet since 1994, which has serious implications for sea-level rise.

Professor Duncan Wingham of University College London (UCL), who led the research, said calculations based on the rate of melting 15 years ago had suggested the glacier would last for 600 years, but the new data points to a lifespan for the vast ice stream of only another 100 years.

They say the center of the glacier is melting the fastest and they're now concerned that if the process continues it may break up and start to affect the ice sheet further inland.

Professor Andrew Shepherd of Leeds University, one of the researchers in the study, said that the melting from the center of the glacier would add about an inch to the global sea level.

He told BBC News the ice trapped behind it would create a 7-11 inch rise of sea level and as soon as they destabilize or remove the middle of the glacier they don't really know what's going to happen to the ice behind it.

"This is unprecedented in this area of Antarctica. We've known that it's been out of balance for some time, but nothing in the natural world is lost at an accelerating exponential rate like this glacier," he said.

In recent years, Pine Island glacier has been the subject of an intense research effort amid fears that its collapse could lead to a rapid disintegration of the West Antarctic ice sheet.

The latest study of the satellite data will add to the alarm among polar specialists.

Meanwhile, scientists are discovering evidence of dramatic change in the Arctic as researchers have been studying the northwestern part of Greenland.

Professor Jason Box of Ohio State University said he was surprised by how little sea ice they encountered in the Nares Strait between Greenland and Canada.

He and a team of researchers have set up time-lapse cameras to monitor the massive Petermann glacier as huge new cracks have been observed and a major part of it is expected to break off soon.

Box said the science community has been surprised by how sensitive these large glaciers are to climate warming.

"First it was the glaciers in south Greenland and now as we move further north in Greenland we find retreat at major glaciers. It's like removing a cork from a bottle," he said.


Image Caption: Calving front of the Pine Island Glacier's ice shelf. Taken by Tom Kellogg on the USCGC Glacier cruise Deep Freeze


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