Winds in the Southern Ocean are now stronger than at any other time in the past 1,000 years and are responsible for leaving Antarctica colder and Australia recording more droughts, a new study has found.
Researchers have found rising levels of carbon dioxide in the atmosphere are strengthening the stormy Southern Ocean winds which deliver rain to southern Australia, but pushing them further south towards Antarctica.
Lead researcher Nerilie Abram, from the Australian National University (ANU) Research School of Earth Sciences, said the findings explained the mystery over why Antarctica was not warming as much as the Arctic, and why Australia faces more droughts.
"With greenhouse warming, Antarctica is actually stealing more of Australia's rainfall. It's not good news - 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," Abram said.
While most of Antarctica is remaining cold, rapid increases in summer ice melt, glacier retreat and ice shelf collapses are being observed in Antarctic Peninsula, where the stronger winds passing through Drake Passage are making the climate warm exceptionally quickly.
By analysing ice cores from Antarctica, along with data from tree rings and lakes in South America, Abram and colleagues were able to extend the history of the westerly winds back over the last millennium.
"The Southern Ocean winds are now stronger than at any other time in the past 1,000 years," Abram 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," Abram said.
"Strengthening of these westerly winds helps us to explain why large parts of the Antarctic continent are not yet showing evidence of climate warming," said co-author Dr Robert Mulvaney, from the British Antarctic Survey.
The study was published in the journal Nature Climate Change