Change of wind brings ice to Antarctica, as Arctic melts

The mystery of the expansion of sea ice around Antarctica, at the same time global warming is melting swaths of Arctic sea ice, has been solved using data from American military satellites.

Two decades of measurements show that changing wind patterns around Antarctica have caused a small increase in sea ice, the result of cold winds off the continent blowing ice away from the coastline.

"Until now these changes in ice drift were only speculated upon using computer models," said Paul Holland at the British Antarctic Survey. "Our study of direct satellite observations shows the complexity of climate change.

"The Arctic is losing sea ice five times faster than the Antarctic is gaining it, so, on average, the Earth is losing sea ice very quickly. There is no inconsistency between our results and global warming."

The extent of sea ice is of global importance because the bright ice reflects sunlight far more than the ocean that melting uncovers, meaning temperature rises still further. This summer saw a record low in Arctic sea ice since satellite measurements began 30 years ago. Holland said the changing pattern of sea ice at both poles would also affect global ocean circulation, with unknown effects. He said while Antarctic sea ice was growing, the Antarctic ice cap - the glacier and snow pack on the continent - was losing mass, with the fresh water flowing into the ocean.

The research on Antarctic sea ice, published in , revealed large regional variations. In places where warm winds blowing from the tropics towards Antarctica had become stronger, sea ice was being lost rapidly. "In some areas, such as the Bellingshausen Sea, the sea ice is being lost as fast as in the Arctic," said Holland.