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Ocean Winds Keep Australia Dry and Antarctica Cold

New research has explained why Antarctica is not warming as much as other continents, and why southern Australia is recording more droughts.

A study published in Nature Climate Change has found that rising levels of carbon dioxide in the atmosphere are strengthening the stormy Southern Ocean winds that deliver rain to southern Australia, but pushing them further south towards Antarctica.

Dr Nerilie Abram of the Australian National University says the findings explain why Antarctica is not warming as much as the Arctic, and why Australia is facing more droughts. “With greenhouse warming, Antarctica is actually stealing more of Australia’s rainfall. As greenhouse gases continue to rise we’ll get fewer storms chased up into Australia,” Abram said.

“As the westerly winds are getting tighter they’re actually trapping more of the cold air over Antarctica. This is why Antarctica has bucked the trend. Every other continent is warming, and the Arctic is warming fastest of anywhere on Earth.”

While most of Antarctica is remaining cold, rapid increases in summer ice melt, glacier retreat and ice shelf collapses are being observed on the Antarctic Peninsula, where the stronger winds passing through Drake Passage are making the climate warm exceptionally quickly.

Until this study, Antarctic climate observations were available only from the middle of the last century. By analysing ice cores from Antarctica, along with data from tree rings and lakes in South America, Abram and her colleagues were able to extend the history of the westerly winds over the past millennium.

“The Southern Ocean winds are now stronger than at any other time in the past 1000 years,” she said. “The strengthening of these winds has been particularly prominent over the past 70 years, and by combining our observations with climate models we can clearly link this to rising greenhouse gas levels.”