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CLIMATE CHANGE: Science Proves Warming of Antarctica

Adrianne Appel* - Tierramérica

BOSTON, Nov 12 2008 (IPS) - The Antarctic holds the world’s largest amount of fresh water in its icy grip, and it is most certainly warming as a result of greenhouse gases, say new scientific studies.

“We’re able for the first time to directly attribute warming in both the Arctic and the Antarctic to human influences,” said Nathan Gillett of the University of East Anglia, in Britain, who led the study.

Evidence of global warming, caused by the release of carbon dioxide and other pollutants into the air, has been found on almost every continent on Earth. The exception was the Antarctic, which holds 90 percent of the world’s ice and 70 percent of the world’s fresh water.

Antarctica, about 1.4 times as large as the United States, has just 20 weather stations from which to gather data, and for this and other reasons, less has been known about the icy continent.

Scientists can see that the warmer parts of Antarctica, including the Western Antarctic and Antarctic Peninsula, which juts north toward South America and is home to millions of seals and penguins and other birds, are seeing temperature increases.

But the frigid East Antarctic, with ice 2,226 metres thick, has seen no significant change in air temperature during the past 50 years – in fact it has shown evidence of cooling – and this has made overall conclusions about the greenhouse gas effect inconclusive.

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) concluded that Antarctica was the only continent where human-caused temperature changes had not been detected, possibly due to insufficient data and observation.

Gillett’s work “demonstrates convincingly what previous studies have suggested: that humans have indeed contributed to warming in both the Arctic and Antarctic regions,” said Andrew Monaghan, of the U.S. National Centre for Atmospheric Research, a close colleague of the researchers.

The team used all data available from 1900 to 2000 from the 20 research stations, and complex computer predictions to reach its conclusions.

The scientists created four computer models, including one that included the impact of greenhouse gases and one that did not. The model with the greenhouse gases produced predictions that matched actual temperature observations up to this point in time, according to their report, “Attribution of polar warming to human influence”, in the scientific journal Nature Geoscience.

Taking averages across all of Antarctica produced findings of “overall warming” of a few tenths of a percent, Gillett said.

But the team found temperature increases on the Antarctic Peninsula of up to 3 degrees Celsius since the 1950s, among the largest increases on Earth, Monaghan said. Still, the average monthly temperature is 1 degree to minus -15 degrees C.

Several large glaciers in the West Antarctic are melting and contributing to a rise in global sea levels, due to warmer ocean currents that are hitting the ice sheets. The average monthly temperature there is -12 C to -35 C.

“This melting of ice shelves has implications for sea level rise,” Gillett said. In 2002, a huge ice shelf on the Peninsula, called the Larsen B, broke apart and melted. It was 3,250 square kilometres in size, he pointed out.

In addition, the team noticed data pointing to a warming along the coasts of East Antarctica, and they expect this warming to accelerate.

Gillett hypothesised that the South Pole cooling may be due to a severe loss of ozone in the Pole’s atmosphere, due to pollution.

He believes that because of his research, scientists can draw a more accurate picture of what the future may look like for Antarctica. Calculations about the melting of ice can now include the impact of global warming.

“We won’t see anything catastrophic in the next century if things continue at the current rate. But the melt could accelerate,” Monaghan said.

The IPCC was unable to include complete and accurate predictions of global sea rise because it did not have adequate Antarctic data. It predicted an increase of between 18 and 59 cm, Gillett said.

In January, IPCC chairman Rajendra Pachauri made a personal plea to scientists to step up their research on Antarctica and Greenland.

“My hope is the next [IPCC] report, if there is one, will be able to provide much better information on the possibility of these two large bodies of ice melting, in what seems like a frightening situation,” Pachauri said.

Research about warming in the Antarctic Peninsula has been building.

Earlier this year, Eric Rignot, of the University of California, reviewed satellite images from 1996 to 2000 and found that ice is definitely melting on the Antarctic Peninsula and in the West Antarctic.

West Antarctica lost about 132 billion metric tons of ice in 2006, compared with about 83 billion metric tons in 1996, Rignot said. The Antarctic Peninsula lost 60 billion metric tons in 2006.

The ice melt would have been enough to raise the world’s sea level by 0.5 mm, if not for a simultaneous ice accumulation in frigid East Antarctica, Rignot said.

Research that shows humans are causing global warming may help bolster efforts to slow the emission of greenhouse gases, primarily by the United States and China, said Meg Boyle, a climate change expert with the environmental watchdog group Greenpeace.

“In the United States, we have a small percentage of the world’s population but we produce 25 percent of the world’s global warming pollution. It is time for us to step up,” she said. She expressed hope that United States President-elect Barack Obama will be more willing to participate in global climate agreements.

(*This story was originally published by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme, United Nations Environment Programme and the World Bank.)