Antarctica Heating Up, "Ignored" Satellite Data Show
for National Geographic News
|January 21, 2009|
Temperatures are warming throughout Antarctica, especially in winter and spring, according to new weather station and satellite data.
The evidence contradicts studies showing that only the Antarctic Peninsula was warming while the rest of the continent has cooled.
The previous data has, in a least one case, fueled skepticism about global warming.
The new study also reveals that western Antarctica may actually be warming faster than the Antarctic Peninsula, "the biggest surprise" to study lead author Eric Steig, a climate researcher at the University of Washington.
"We can't say this with confidence, but our results at least hint that that may be the case."
Previous papers had already hinted at warming in eastern Antarctica, Steig said.
The Antarctic Peninsula, the farthest portion of the continent from the South Pole, has warmed faster than any other place in the world in the past 50 years—by some estimates as much as 4.5 degrees Fahrenheit (2.5 degrees Celsius).
Such increases have caused dramatic ice shelf collapses.
(Related: "Antarctica Ice Loss Faster Than Ten Years Ago" [November 4, 2008].)
Steig also emphasized that the huge continent remains a complicated place, with both warming and cooling trends varying with geography and season.
Forest for the Trees
Steig and his team were conducting climate studies from ice cores in western Antarctica and needed up-to-date data for comparison.
With no permanent research stations, the scientists lacked reliable long-term records, Steig said.
"We recognized that to get an idea of what was happening in western Antarctica, we would have to rely on using weather station data from other parts of Antarctica."
Because weather stations are so sparse, past studies relied weighted averages, for the missing areas that are based on temperatures from surrounding locales.
"In our case, we recognized that there was a better way to [connect data] between weather stations in Antarctica, which was to use satellite data," said Steig, whose results appear in this week's issue of the journal Nature.
The team combined spotty weather station records and satellite data between 1957 and 2006.
"In retrospect, it is pretty obvious that ignoring the satellite data, as others had done, was really missing the forest for the trees," Steig said.
The researchers found that the temperature over western Antarctica is rising 0.31 Fahrenheit (0.17 degree Celsius) per decade, with a continental increase of 0.18 Fahrenheit (0.1 degree Celsius).
Worldwide, the temperature has climbed an average of 1.08 Fahrenheit (0.6 degrees Celsius) over the past 50 years, said study co-author Drew Shindell of NASA's Goddard Institute for Space Science.
A hole in the ozone layer over eastern Antarctica drives winds that help keep temperatures down, but that effect is likely to lessen as the layer heals, leading to still more warming, Shindell added.
In 2002, Peter Doran, an earth and environmental scientist at the University of Illinois at Chicago, published results that showed more parts of Antarctica than not were cooling.
But Doran wrote a 2007 op-ed in the New York Times lamenting that his earlier study had been cited by global warming skeptics, including the late Michael Crichton in his 2004 novel State of Fear.
(Get fast facts on global warming.)
Doran also wrote that more weather stations on Antarctica and longer-term data would be needed to demonstrate a clear trend in Antarctica.
This week, Doran called the new Nature paper "an excellent and thorough study by a top-notch group."
"First, they have brought in a combination of data sources and added another decade and a half to what we reported on. The argument for an expanded warming in [western] Antarctica based on this seems reasonable."
Continued satellite measurements, more weather stations, and core samples to reconstruct historic temperatures are all needed to complete the Antarctic climate picture, Steig said.
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