Antarctic Ice Sheet is shrinking also

A study just released Sunday Jan. 12th 2008 suggests that the Antarctic Ice Sheet is shrinking at a rate that increased dramatically from 1996 to 2006. (Note: previously the Antarctic was thought to be holding it's own or growing).

The research project, led by Dr. Eric Rignot of the Radar Science and Engineering section at NASA's Jet Propulsion Lab found that the ice mass loss increased by 75% over the 10 year period. There was a net loss of 196 billion tons of ice in 2006 compared to 112 billion tons in 1996. The ice loss in 2006 raised sea levels about a 1/2 millimeter. The biggest losses were in West Antarctica and along the Antarctic Peninsula, while East Antarctica was fairly stable and has seen a slight increase in mass. According to the GlobeandMail.com article, the figures were calculated by deducting the amount of ice losses on the continent from the amount of snow computer models indicate it receives.The figures were based on satellite data on ice thickness and the speeds at which glaciers are flowing into the ocean.

Dr. Rignot said the shrinkage can be attributed to upwelling of warm waters along the Antarctic coast, which is causing some glaciers to flow more rapidly into the ocean. He suspects the trend is due to global warming and not a normal natural fluctuation.

Some experts have even speculated that global warming might lead to increases in ice accumulation in Antarctic's interior due to more snowfall. However, many experts say that this effect is unlikely to offset Antarctica's contribution to sea level rise because of the rapid melting of coastal glaciers, as the article explains.

"The concept that global warming will increase precipitation in Antarctica and mitigate sea level rise is a lullaby," Dr. Rignot said. The main driver for mass balance is the rate of glacier flow to the sea, not the precipitation rate, since other recent studies showed that there has not been a significant change in the actual precipitation rate.

The results of the study appear in the current issue of Nature Geoscience.

Source:
global-warming.accuweather.com...