22 January 2008
Skeptics about global warming often point to Antarctica to show that Al Gore and others who worry about climate change have exaggerated the dangers greatly. They may concede that the Arctic is melting and even that Greenland is beginning to appear a bit shaky.
But look at Antarctica, they will say. It's actually growing colder, and the ice sheet is thickening.
That argument is becoming harder to sustain. According to a study published last week in the journal Nature Geoscience, changes in water temperature and wind patterns related to global warming have begun to erode vast ice sheets in western Antarctica at a much faster rate than anyone had previously detected.
The study pointed out that the ice loss is very small compared with the continent's miles-deep ice sheets. Even so, the study suggests that if the trend continues, global sea levels could rise higher and more swiftly than previously supposed. The findings give more urgency to the search for a new global agreement to limit emissions of carbon dioxide and other greenhouse gases.
There has always been uncertainty over Antarctica's weather, partly because it is so hard to find what is happening in large parts of the continent. And there are, in effect, two Antarcticas. East Antarctica, which makes up about 90 percent of the total, sits above sea level and is relatively stable, with increased snowfall compensating for any loss of ice. A study in 2002 concluded that the interior had actually cooled over the previous decade.
Then there is the western shelf, an expanse of ice and snow roughly the size of Texas and largely below sea level. Using measurements from satellites that scanned about 85 percent of Antarctica's coasts from 1996 to 2006, the study's authors found that West Antarctica has been losing ice at a rate that is 60 percent faster than 10 years ago.
The Intergovernmental Panel on Climate Change, which shared the Nobel Peace Prize last year with Gore, predicted that if nothing is done to slow the increase in global warming gases, the world's oceans could rise as much as two feet in this century. Many scientists think the panel underestimated glacial flows.
It is too early to predict how much the melting from Antarctica will add. Still, the new findings are unsettling and yet another warning that there is no way to deny and nowhere to hide from global warming.
http://www.iht.com/articles/2008/01/22/opinion/edwarming.php
