for National Geographic News
The air over Antarctica has warmed dramatically over the past 30 years, according to a new study of archived data collected by weather balloons floated over the icy continent.
The greatest warmingnearly 1.4ºF (0.75ºC) per decade in the winterhas occurred about 3 miles (5 kilometers) above the surface.
Scientists are hard pressed to explain the temperature spike, which is three times larger than the global average. The rise cannot be explained by the climate models scientists use to predict the effects of global warming from increased greenhouse gases.
"That could point to some mechanism of climate change we don't understand, a failing in these models, or just a result of natural climate variability," said John Turner, a climate scientist with the British Antarctic Survey in Cambridge, England.
Meanwhile, surface temperatures have increased 4.5ºF (2.5ºC) in the last 50 years on the Antarctic Peninsula, the mountainous arm that trails toward the southern tip of South America.
"But the rest of Antarctica has done virtually nothing [at the surface]", Turner said.
Turner is the lead author of the study, which appears in tomorrow's issue of the journal Science.
David Bromwich, a meteorologist with the Byrd Polar Research Center at Ohio State University in Columbus, said there's "no doubt this [warming] is real."
But, he added, the finding only "deepens the mystery of what's going on over Antarctica."
According to Turner, the unexpected warming could affect snowfall across the continent, which might have implications for global sea-level rise.
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