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Antarctic Glaciers' Ice Loss Has Scientists Puzzled
Date: Monday, March 19 2007
Topic:


Some of the largest glaciers in Antarctica and Greenland are moving in unusual ways and are losing increased amounts of ice to the sea, researchers said yesterday.

...... Although the changes in Greenland appear to be related to global warming, it remains unclear what is causing the glaciers of frigid Antarctica and their "ice streams" to lose ice to the ocean in recent years, the researchers said.


The Antarctic ice loss is not caused by melting but rather by the pushing of ice streams into the ocean by several glaciers in the west of the continent, has picked up speed in recent years.

......But Wingham said that because researchers did not have good measures of the depth of the Antarctic ice shelf until about 10 years ago, scientists do not know whether this is a natural variation or a result of human activity.

Complicating the situation for those studying Antarctica:

......some parts of the continent are gaining ice depth through snowfall while;

......temperatures on the continent's closest point to South America, are rising faster than almost anywhere else on the planet.


The surprisingly fast-moving glaciers are largely on the West Antarctic ice sheet.


Each year the ice loss from Greenland and Antarctica amounts to about 10 percent of the rise in the global sea level, which totals about one-tenth of an inch per year. The net loss of Antarctic ice is estimated to be 25 billion metric tons a year, despite the growth of the ice sheet in East Antarctica.


In Greenland, glaciers appear to be moving more quickly to sea because melting ice has allowed the sheet to slide more easily over the rock and dirt below.

......In Antarctica, the loss is believed to be associated with the breaking off into seawater of ice deep under the ice sheet with little-understood internal dynamics that put increased pressure on the massive ice streams.


SOURCE:..... Antarctic Glaciers' Sloughing of Ice Has Scientists at a Loss
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Rethinking Ice Sheet Time Scales

Science 16 March 2007: Vol. 315. no. 5818, pp. 1508 - 1510


Today, we can monitor ice sheets with unprecedented spatial and temporal resolution. The resulting news has consistently had an element of surprise with regard to time scales. Invariably, processes are happening more rapidly than previously thought possible.


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FROM 2006:

Siberian Heatwave - & - NOAA's Arctic Report

........in northern Siberia. Ice packs are failing to form, forcing polar bears, seals and walruses to remain on land, disrupting breeding cycles.

.......Jacqueline A. Richter-Menge of the Cold Regions Research and Engineering Laboratory in Hanover, N.H., said the sea ice decline is now being observed in both winter and summer.


The State of Our Climate - An Alarming Synthesis of Articles

......The authors divided the last four years into 2002-04 and 2004-06. In that time, the rate of melt (in cubic km) has increased 2.5X for the whole of Greenland, but increased 12X for the southern part.

..... a ship could sail unhindered from Europe's most northerly outpost to the North Pole itself.









[Proofreader's note: this article was edited for spelling and typos on March 19, 2007]

Antarctic Glaciers' Sl... Rethinking Ice Sheet Ti... Siberian Heatwave - &a... The State of Our Clima...



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