Thursday, January 22, 2009

Scientists find evidence Antartica is warming

ABC News Online, Posted Thu Jan 22, 2009 1:42pm AEDT

For climate scientists, it has been one of the great questions.

While the rest of the world has been warming up, the interior of Antarctica has been getting colder.

The thinking was that stronger winds, ozone layer holes and moist air were bringing in more snow to keep temperatures down.

But new research has found that, in fact, the iciest continent is undergoing the same changes as the rest of the planet.

The research, conducted by a group of scientists in the United States led by Professor Eric Steig at the University of Washington, has been published in the journal Nature.

"Most studies of Antarctic climate change in the recent past have relied on weather records, which are located at the Antarctic research stations," Professor Steig told the ABC's AM program.

"And most of those stations, there are 42 of them, are on the coastline or near the Antarctic coastline, with only two in the interior of the continent.

"Some of those stations have shown cooling in recent decades, including one of those in the centre of the continent at the South Pole, and that's resulted in the popular notion that all of Antarctica is cooling."

Working out what has been happening across the icy interior has been the challenge.

"What we did is we took advantage of the fact that, in fact, there is data. There's over 25 years now of data from satellites, which provides an alternative way to measure the temperature," Professor Steig said.

West Antarctica warming up

By correlating the two, the research team believes it has come up with an accurate picture stretching back half a century, and it shows western Antarctica especially has been getting warmer by about a 10th of a degree every decade.

"What we found, in a nutshell, is that Antarctica is not cooling," Professor Steig said.

"Now some parts of it have been cooling, but only since the late 1970s, and only in certain seasons, primarily in autumn.

"On average the entire continent is warming and especially it is warming in winter and spring. Finally, west Antarctica, just like the Antarctic peninsula, is warming in all seasons."

A lot of the concern about climate change has focused on the northern polar region and the potential for the melting of Greenland's ice sheet.

Professor Barry Brook, from the University of Adelaide's Institute for Climate Change, welcomes the new research, which he says will improve understanding of potential threats in the south - major ice sheets like those in western Antarctica.

"There's a number of large ice sheets there that are grounded below sea level and so if they start to melt they contribute to sea level rise," he said.

"And so the worry is that if temperatures are going up more rapidly in west Antarctica than we previously expected, the sea level could be rising faster or will continue to rise faster this century than we would have otherwise anticipated."

- Adapted from a report by Shane McLeod for AM on January 22.

Study findings contradict Antarctic cooling theory

By ABC correspondent Shane McLeod

Posted Thu Jan 22, 2009 9:31am AEDT
Updated Thu Jan 22, 2009 9:30am AEDT

Scientists believe global warming is affecting Antarctica at the same rate as the rest of the planet, contradicting earlier studies that suggested the coldest continent was getting cooler.

Climate scientists had puzzled over Antarctica, believing that while some parts of the continent like the Antarctic peninsula had been warming up, the vast interior was getting cooler.

Tracking temperature trends across the cold and barren continent is difficult.

Long term weather records are limited, but scientists in the United States used them in conjunction with more recent satellite data to calculate half a century of records for the entire continent.

Their results, published in the journal Nature, show that western Antarctica is warming a lot faster than had been thought, at a rate of about 0.1 degrees Celsius every decade.

Eastern Antarctica is cooler, but overall the continent is getting warmer, mirroring the rest of the planet.

The scientists believe warmer sea temperatures and winds are behind the warming trend.

No comments: