America may be hit hardest by collapse of West Antarctic Ice Sheet

May 15th, 2009 - 12:16 pm ICT by ANI  

Washington, May 15 (ANI): A new study has suggested that a total or partial collapse of the West Antarctic Ice Sheet (WAIS) as a result of global warming would lead to levels on the US seaboards to rise 25 percent more than the global average and threaten cities like New York, Washington, D.C., and San Francisco.

The western ice sheet in Antarctica, known as WAIS, is of particular interest to scientists due to its inherent instability, a result of large areas of the continent’s bedrock lying below sea level.

“There’s a vast body of research that’s looked at the likelihood of a WAIS collapse and what implications such a catastrophic event would have for the globe,” said Jonathan Bamber, lead author of the study.

“But all of these studies have assumed a 5-meter to 6-meter contribution to sea level rise. Our calculations show those estimates are much too large, even on a thousand-year timescale,” he added.

Bamber and his colleagues found a WAIS collapse would only raise sea levels by 3.3 meters, or about 11 feet.

The study authors used models based on glaciological theory to simulate how the massive ice sheet likely would respond if the floating ice shelves fringing the continent broke free.

Vast ice shelves currently block WAIS from spilling into the Weddell and Ross seas, limiting total ice loss to the ocean.

According to theory, if these floating ice shelves were removed, sizeable areas of WAIS would essentially become undammed, triggering an acceleration of the ice sheet toward the ocean and a rapid inland migration of the grounding line.

If such a large mass of ice steadily melted over 500 years, as has been suggested in earlier studies, it would add about 6.5 millimeters or a quarter of an inch per year to sea level rise - about twice the current rate due to all sources.

“Interestingly, the pattern of sea level rise is independent of how fast or how much of the WAIS collapses,” said Bamber.

“Even if the WAIS contributed only a meter of sea level rise over many years, sea levels along North America’s shorelines would still increase 25 percent more than the global average,” he added.With less mass at the South Pole, Earth’s gravity field would weaken in the Southern Hemisphere and strengthen in the Northern Hemisphere, causing water to pile up in the northern oceans.

This redistribution of mass also would affect Earth’s rotation, which in turn would cause water to build up along the North American continent and in the Indian Ocean. (ANI)

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