Antarctica Gives Mixed Signals on Warming

Bijal P. Trivedi
National Geographic Today
January 25, 2002

Every climate model predicts that if global warming is indeed underway, the greatest warming will occur at the poles. For this reason, many scientists are closely watching these two regions for signs of ecological change.

But the situation isn't always clear. Based on several recent studies, Antarctica is either heating up or heading for the big chill.

Research published January 25 in the journal Science concluded that rising global temperatures have heated up the lakes on Signey Island, northwest of the Antarctic Peninsula—a narrow sliver of land that juts out toward South America—triggering dramatic ecological changes.

Just last week, however, other researchers reported that, rather than melting and thinning, ice sheets in Antarctica have been thickening, and the continent has been cooling for the last couple of decades.

What does this say about global warming trends?

"In Antarctica, there is not a strong heating or cooling trend either way," said John Walsh, a polar climate specialist at the University of Illinois in Chicago.

"Antarctica is a tricky region and is more likely to do its own thing as the rest of the planet warms," he added. One reason for this, Walsh explained, is that compared with the Arctic, Antarctica is more susceptible to heat loss and gain from the ocean.

Walsh and his colleagues reported last week, also in Science, that contrary to previous reports, Antarctica is cooling.

If the whole of Antarctica were divided into a grid, said Walsh, about 60 to 70 percent of the squares would reveal a cooling trend, while warming would be seen in the other 30 to 40 percent of the overall area. "So there's a slight net cooling for the entire continent," Walsh said.

Inconsistent Reports

The total surface area of Antarctica is 5.1 million square miles (13.2 million square kilometers), but the area doubles in winter with the addition of sea ice, said Lloyd Peck, of the Natural Environment Research Council in Cambridge, United Kingdom.

"You can't expect an area three times the size of Australia to behave the same way throughout," said Peck, a co-author of the new study on the Signey Island lakes.

Walsh and his colleague Peter Doran, who collaborated on the recent study that concluded Antarctica is cooling, say past reports of global warming in the region were skewed by the nature of the measurements.

Continued on Next Page >>




NEWS FEEDS     After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.   After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.

Get our news delivered directly to your desktop—free.
How to Use XML or RSS

National Geographic Daily News To-Go

Listen to your favorite National Geographic news daily, anytime, anywhere from your mobile phone. No wires or syncing. Download Stitcher free today.
Click here to get 12 months of National Geographic Magazine for $15.