Polar paradox: Warmer planet, larger ice cap.

Nature puzzles over an unforeseen consequence of global warming – an expansion of Antarctic sea ice as the climate warms:

While sea ice at the North Pole has shrunk substantially over the past three decades, scientists have struggled to explain why sea ice near the South Pole has grown in extent over the same period.

“The paradox is that global warming leads to more cooling and more sea ice around Antarctica,” says Richard Bintanja, a climate researcher at the Royal Netherlands Meteorological Institute in Utrecht. Bintanja and his colleagues show that enhanced melting of the Antarctic ice sheet — which is losing mass at a rate of 250 gigatonnes yearly — has probably been the main factor behind the small but statistically significant sea-ice expansion in the region.

There are other plausible explanations for Antarctic sea-ice expansion, however. “The mechanism could be completely true, but this study does not demonstrate that increased melting has made a significant contribution to the increase in sea-ice cover,” says Paul Holland, an ocean modeller at the British Antarctic Survey in Cambridge, UK, who last year co-authored a study showing that the sea-ice expansion is caused in large part by regional wind patterns.

Wind advocates and melting ice advocates are kinda slugging it out on this one. Whoever’s right, the planet’s definitely changing is the thing.