Launching weather balloons has been a nearly daily habit at some Antarctic research facilities since 1957. Carrying radiosondes--instruments that measure atmospheric conditions such as temperature and wind speed--the balloons travel as high as 12 miles or more. A new analysis of the past 30 years of records from nine research stations, including Amundsen-Scott at the South Pole, reveals that the air above the entirety of Antarctica has warmed by as much as 0.70 degree Celsius per decade during the winter months.

John Turner of the British Antarctic Survey and his colleagues report in today's issue of Science that this warming trend is consistent across data from multiple stations run by multiple countries using multiple types of instruments. Previous studies had shown that Antarctica's surface temperatures had warmed by roughly 2.5 degrees C over the last half century, but this study provides the most complete look at atmospheric trends to date.

"The rapid surface warming of the Antarctic Peninsula and the enhanced global warming signal over the whole continent shows the complexity of climate change," Turner says. "Greenhouse gases could be having a bigger impact in Antarctica than across the rest of the world and we don't understand why."

This warming has implications for snowfall on the continent as well as the melting of land-based ice reserves, potentially leading to global sea-level rise, the researchers warn. Although they cannot ascribe a particular cause to the warming, they ruled out several other potential explanations, including heat transfer from other regions (there was no observed change in wind patterns) and solar radiation changes (the sun is either at or below the horizon throughout the winter months in question).

And although current computer models fail to predict this warming trend, the scientists argue that the data is consistent with what would be expected as a result of increasing greenhouse gases. "Our next step," Turner says, "is to try to improve the models."