Phys.org - More Powerful Winds (Thanks To Warming) Key To Expanded Antarctic Sea Ice

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Lead author of the report Jan Lieser, a marine glaciologist at the Antarctic Climate & Ecosystems centre, said researchers were confident of the physical driver behind the increase of ice: wind. Dr Lieser said that global warming and, to a lesser extent, the ozone hole, had been found to be the main physical drivers of the increase in westerly winds over the Southern Ocean, what he dubbed a "double whammy from above and below".

He said sea ice is a highly sensitive, easily-movable substance, and if you have strong winds, the sea ice will move around with the wind. He explained that a warmer atmosphere increases convection, producing greater wind speeds in certain bands of the world.

In the Southern Ocean surrounding Antarctica, this warmer atmosphere has manifested itself in stronger westerlies, which are pushing the ice out further than it would normally reach. "We know the sea ice is growing because the westerly winds are intensifying around the continent, and that pushes the sea ice further into the southern ocean," said Dr Lieser.

Paradoxically, warmer sea temperatures are also helping to create more sea ice. The warmer water creates a thinner sheet of ice that is then more easily broken up and moved by the increased wind. This spreads the sheet further and actually results in more ice coverage.

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http://phys.org/news/2014-03-antarctic-sea-ice-arctic.html