All Antarctica seems to be warming, report says Review of 50 years of data shows that the east side of the continent is also heating up, scientists say

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The climate trend that is raising temperatures across most of the world is warming all of Antarctica despite earlier signs that most of the ice-covered continent has cooled during the past 50 years, researchers are reporting today.

The scientists stop short of claiming with certainty that wind-borne greenhouse gases from global industries on other continents are responsible for Antarctica's warming, but they say their evidence makes them "almost certain" that human activity carries at least some of the blame.

For years the Intergovernmental Panel on Climate Change, whose scientists track global warming year by year, has reported that greenhouse gases and global warming have clearly hit six of the world's seven continents, but that the evidence from Antarctica is still unclear. West Antarctica is known to be warming strongly, but the climate of the much larger eastern area was said to be cooling, some scientists have argued.

Now the issue has apparently been resolved.

In a report published today in the journal Nature, climatologists Eric Geist of the University of Washington and Drew Shindell of NASA's Goddard Institute for Space Studies say that for the first time they combined satellite observations over the entire continent with evidence from more than 100 manned and unmanned weather stations both inland and along the continent's coasts to determine climate trends for the past 50 years.

During an hour-long teleconference Wednesday, the scientists said their data clearly shows that on average the entire Antarctic continent has been gradually warming at least since 1957.

West Antarctica, separated from the far larger eastern part by the towering Transantarctic mountain range, has long evidenced a strong warming trend. And the Antarctic Peninsula, warmer than everywhere else in the western region, is where massive ice shelves have collapsed into the sea as springtime temperatures rise above the melting point there.

But East Antarctica has been a very different story. Here, many scientists have contended that the huge region has been cooling over the past half-century.

A leading scientist who has long collected data supporting that cooling argument conceded, in an e-mail to The Chronicle on Wednesday, that the evidence in the new report "lends confidence" that the new findings on Antarctic temperature trends "are robust."

Andrew Monaghan of the National Center for Atmospheric Research in Boulder, Colo., also was impressed by the new findings and said he's convinced that greenhouse gases - known as "anthropogenic" influences - have played a role in warming Antarctica's climate.

"My opinion is that anthropogenic impacts - through both greenhouse gases and stratospheric ozone - are having a discernible impact on Antarctic climate variability and will continue to do so," Monaghan said.

During Wednesday's teleconference, Shindell said wind patterns across Antarctica make it difficult to pin down the role of greenhouse gases in warming the continent, but human activity in the world's other continents should be added in as an influence pushing Antarctic temperatures up.

"We're almost certain that increases in greenhouse gases on other continents are contributing to this warming in Antarctica," Shindell said.

Scientists have been severely hindered in studying the icy continent's climate trends because most manned weather stations are located along the accessible coasts. But Geist said his team was able to gather valuable satellite data covering the past 25 years. They then combined that data with records from unmanned stations located inland and left by visiting scientists over the years since the International Geophysical Year of 1957-58.

The result, Geist said, was a combined record clearly showing that East Antarctica, too has been warming over the past 50 years - although warming on the continent's western side has been twice as rapid.

While the numbers are complicated, the team's evidence indicates that over the entire Antarctic continent - where year-round temperatures average nearly 50 degrees below zero - the average temperature increase for the past 50 years has been half a degree Celsius, or just under one full degree Fahrenheit, Geist said.

One degree may not seem like much, but a two-degree global increase - universally forecast before the end of this century - would pose major threats to world stability. Scientists predict that food crops would die in some regions and increase in others, and rising sea levels, caused by melting ice, would drown many low-lying coasts and islands, particularly in developing nations where poverty is already endemic.