RESEARCHERS FIND ANTARCTIC ICE IS THICKENING

Associated Press, 18 January 2002
 HYPERLINK "http://www.usatoday.com/news/science/cold-science/2002-01-18-wais-thicker.htm" \t "linkWin" http://www.usatoday.com/news/science/cold-science/2002-01-18-wais-thicker.htm

WASHINGTON (AP) New measurements show the ice in West Antarctica is thickening, reversing some earlier estimates that the sheet was melting.

Looking across the ice from an ice-core drilling tower at the Siple Dome field camp in 1999. Scientists drilled into the ice here to study the history of the West Antarctic Ice Sheet.

Scientists concerned about global warming have worried that higher temperatures could melt the massive ice sheet, causing a rise in sea levels worldwide.

But new flow measurements for the Ross ice streams, using special satellite-based radars, indicate that movement of some of the ice streams has slowed or halted, allowing the ice to thicken, according to a paper in the Jan. 18 issue of the journal Science.

If the thickening is not merely part of some short-term fluctuation, it represents a reversal of the long retreat of the ice, say researchers Ian Joughin of the California Institute of Technology and Slawek Tulaczyk of the University of California, Santa Cruz.

Their finding comes less than a week after a separate paper in Nature reported that Antarctica's harsh desert valleys - long considered a bellwether for global climate change - have grown noticeably cooler since the mid-1980s.

Air temperatures recorded continuously over a 14-year period ending in 1999 declined by about 1 degree Fahrenheit in the polar deserts and across the White Continent, that paper said. The cooling defies a trend spanning more than 100 years in which average land surface temperatures have increased worldwide by about 1 degree Fahrenheit. The scientists said Antarctica is the only continent that is cooling. They can not say why.

In their paper, Joughin and Tulaczyk suggest the West Antarctic ice streams may be undergoing the same transition from shrinking to growing that appears to have occurred on a neighboring stream 150 years ago.

The results, they add, suggest a reduced possibility of the feared massive collapse of the ice field.

"Perhaps, after 10,000 years of retreat from the ice-age maximum, researchers turned on their instruments just in time to catch the stabilization or re-advance of the ice sheet," Richard B. Alley of Pennsylvania State University, wrote in a commentary accompanying the Science paper.

But he warned that coastal property owners should not become too optimistic about the findings, since the instrumental record is short and coastal ice streams have changed periodically over the centuries.

Copyright 2002 The Associated Press

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ANTARCTIC ICE SHEETS ARE GROWING

Die Welt am Sonntag, 6 March 2005
 HYPERLINK "http://www.welt.de/data/2005/03/07/606129.html" \t "linkWin" http://www.welt.de/data/2005/03/07/606129.html

[...] The West Antarctic peninsula only covers one tenth of the South Pole's ice. There are rarely spectacular reports about the much larger parts of the continent. These do not provide a uniform scientific picture. In total, however, the ice masses of the continent, which hold about 70 per cent of the world's fresh water resources, seem to be growing. This conclusion was reported at the Earth Observation summit in Brussels in the middle of February by Antarctic researcher Duncan Wingham (University College London).

Wingham presented new satellite data which show that the Antarctic ice cover is getting thicker. "To claim that the ice sheets are melting is rather daring," Wingham said in an interview with Die Welt. Wingham presented radar measurements taken by the European satellites ERS-2 and Envisat, whose altimeter exactly measures elevations on the earth's surface down to two centimeters by means of electromagnetic wave pulses. This way, changes of the ice cover can be identified over many years. Soon, even more precise measurements will be possible once the European satellite Cryo Sat is going to be launched later in June.

Orbiting the Polar Regions, Cryo Sat will take exact measurements (at the millimeter level) for at least three years of the ice thicknesses on both the mainland and the sea at both poles. At a conference in Frascati next week, these operations are going to be prepared.

However, whether Cryo Sat's measurements will be able to clarify how the ice cover of the Antarctic thick (which is up 4770 meters thick) will evolve in the future, remains questionable. Systematic climate research has been going on for some 30 years on the seventh continent -with contradictory findings: the climate of the Antarctic is complex.

A temperature rise over the western peninsula has coincided with a cooling of the south part of the continent. And even in the west the ice cover has been growing. Standard explanations claim that a slight warming will lead to intensified snow whenever it freezes. A global temperature rise could possibly lead to the thickening of the Antarctic ice cover altogether. In any case, the doomsday scenario of an Antarctic meltdown - and consequently a rise in sea level of up to 60 meters - seems rater unrealistically....