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CLIMATE CHANGE: New Findings Show Antarctic Warming

Stephen de Tarczynski

MELBOURNE, Feb 1 2009 (IPS) - Although Antarctica has hitherto been believed to be the only continent to buck the global trend of warming, new findings by United States-based scientists indicate that the coldest continent is indeed hotting up in a similar way to the rest of the world.

“The thing you hear all the time is that Antarctica is cooling and that’s not the case. If anything it’s the reverse, but it’s more complex than that. Antarctica isn’t warming at the same rate everywhere, and while some areas have been cooling for a long time the evidence shows the continent as a whole is getting warmer,” says Eric Steig, a professor of earth and space sciences at the University of Washington.

Steig was lead author of a paper published in January in the science journal Nature which documents Antarctica’s warming.

While the consensus regarding the southern continent had previously been that only the Antarctic Peninsula had been warming – both of the Antarctic’s two other geographic regions, East and West Antarctica, were believed to be cooling – Steig’s team of researchers combined previously available data from weather stations with information from satellites.

Most of the older weather stations are located within a short distance from the coast, but satellites, in addition to some unmanned stations operating further inland, provide scientists with a more accurate picture of temperature trends in Antarctica’s interior.

Steig’s team, which included researchers from across the U.S. – their work was funded by the National Science Foundation – found that satellite data corresponded closely to temperature measurements taken from weather stations.


“People were just calculating with their heads instead of actually doing the math. What we did is interpolate carefully instead of just using the back of an envelope. While other interpolations had been done previously, no-one had really taken advantage of the satellite data, which provides crucial information about spatial patterns of temperature change,” he says.

Satellites, which have the advantage of covering the entire continent, measure the intensity of infrared light radiated by the snowpack to calculate surface temperature.

Contrary to previously-held belief, the scientists found that West Antarctic has actually been warming, with temperatures increasing by more than one-tenth of a degree Celsius per decade over the past 50 years.

Such an increase in the warming of West Antarctica more than offsets the cooling still observed in the continent’s east. Combined with the warming process taking place on the Antarctic Peninsula, Antarctica as a whole is indeed getting hotter.

And despite the whole of Antarctica essentially being a desert, major differences between the two regions are evident.

“West Antarctica is a very different place to East Antarctica, and there is a physical barrier, the Transantarctic Mountains, which separate the two,” says Steig.

West Antarctica, with an average elevation of around 6,000 feet above sea level, is subject to relatively warm, moist storms, while East Antarctica receives far less snowfall. The East’s average elevation, at about 10,000 feet, is also considerably higher than in the West.

Ian Allison, a glaciologist with the Australian Antarctic Division – part of the Australian government’s department of the environment, water, heritage and the arts – says that Antarctica, along with its polar opposite, the Arctic, are earth’s “heat sinks”.

“They’re important because of the feedback processes that can occur,” he says, adding that the warming identified in the new research can be observed in the melting of Antarctica’s sea ice.

“If you get warming and the sea ice melts then you lose what is a highly reflective surface. Then the dark ocean, which absorbs more sun, warms up more and more ice disappears and you get a positive feedback,” he says.

Allison told IPS that he is not overly surprised by the findings of Steig’s team.

While accurate information on temperature patterns in West Antarctica has been hampered by a paucity of weather stations, the adjacent “Antarctic Peninsula has been one of the areas on earth that has been warming the greatest,” he says.

“It was always a bit strange,” adds Allison.

The Australian scientist believes that the new findings now provide for a far more complete view of the world’s changing climate.

The final report by the Intergovernmental Panel on Climate Change (IPCC), released in 2007, noted that in each continent besides Antarctica, greenhouse gas emissions stemming from human activities were the likely cause of warming.

Allison told IPS that this “wasn’t done for Antarctica because there wasn’t sufficient data available.”

He argues that with the new findings, Antarctic warming as a result of greenhouse gases can now also be included with the other continents.

“For every continent except for Antarctica, the only way you can fit the observed temperature [changes] is having enhanced greenhouse gases,” he says.

The results of the research “show a warming that is consistent with the others. If the other continents need greenhouse gases to explain [temperature increases] then I would extend it to Antarctica as well,” says Allison.

And with at least seven ice shelves having collapsed on the Antarctic Peninsula in recent decades – the British Antarctic Survey has also warned that the Wilkins Ice Shelf, with a massive area of 15,000 square kilometres, is set to break away shortly from the peninsula – it appears that the continent’s warming is having major implications.

However, Allison opines that the ice sheets on the peninsula are collapsing due to other factors. “What we’ve seen there is a number of ice shelves collapsing, but they’re collapsing more because the ocean waters have warmed and they’ve thinned and then you’ve got runaway processes starting,” he says.

Ice sheets in East and West Antarctic are not expected to suffer from the same damage inflicted on the continent’s peninsula by the warming observed by Steig and his team of researchers.

“This warming that they’re claiming now is not going to be enough to cause the ice sheet to melt because most of the ice sheet is presently well below freezing point temperatures, apart again from up the peninsula,” says Allison.

 
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