Earth Changes
Rising carbon dioxide levels in the atmosphere were strengthening the winds, already dubbed the "Roaring Forties" for their ferocity, and pushing them further south towards Antarctica, researchers from the Australian National University (ANU) said.
"The Southern Ocean winds are now stronger than at any other time in the past 1,000 years," said the study's lead researcher Nerilie Abram of an ocean notorious for having some of the fiercest winds and largest waves on the planet.
"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."
The new research, which was published in the Nature Climate Change journal, explains why Antarctica is not warming as much as other continents.
The westerly winds, which do not touch the eastern parts of Antarctica but circle in the ocean around it, were trapping more of the cold air over the area as they strengthened, with the world's southernmost continent "stealing more of Australia's rainfall", Abram said.
"This is why Antarctica has bucked the trend. Every other continent is warming, and the Arctic is warming fastest of anywhere on earth," she said.
The study's authors analysed ice cores from Antarctica, along with data from tree rings and lakes in South America, using the southern hemisphere's most powerful supercomputer "Raijin", which is based at the ANU.
The research helped to explain why the westerlies were further cooling already cold parts of the continent even as they were also driving "exceptionally quicker" warming in the Antarctic Peninsula, which juts out into their path, Abram said.
The strengthening westerlies drive up the temperature at the peninsula -- the only part of the Antarctica that is hit by the wind -- through the warm, moist air they carry from the Southern Ocean.
This has made the peninsula the fastest-warming place in the southern hemisphere, with scientists concerned about the stability of the ice sheets and sea level rises in the region.
The shift in the westerlies -- approximately 200 kilometres in the 20th century -- was driven by human emissions of carbon dioxide, said research fellow Steven Phipps of the University of New South Wales, who worked on the climate modelling used in the study.
From the 1970s, the shift was exacerbated by the expanding ozone hole caused by human emissions of chlorofluorocarbons (CFCs), Phipps added.
"Even for a mid-range climate scenario, the trend is going to continue in the 21st century," Phipps said, adding that southern Australia was likely to experience more dry winters.
Source: Agence France-Presse
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"In the Southern Hemisphere, autumn is well underway, and sea ice extent is growing rapidly. Antarctic sea ice extent for April 2014 reached 9.00 million square kilometers (3.47 million square miles), the largest ice extent on record by a significant margin. This exceeds the past record for the satellite era by about 320,000 square kilometers (124,000 square miles), which was set in April 2008.
Following near-record levels in March, a slightly higher-than-average rate of increase led to a record April ice extent, compared to the satellite record since 1978. During April, ice extent increased by an average of 112,600 square kilometers (43,500 square miles) per day. Ice extent on April 30 was a record for that day; record levels continue to be set in early May.
Sea ice extent anomalies are highest in the eastern Weddell Sea (south of the South Atlantic Ocean near longitudes 45°W to 10°E) and along a long stretch of coastline south of Australia and the southeastern Indian Ocean (spanning 40°E to 170°E longitude). These areas of unusual ice extent are following similar anomalies seen in March. April also saw significant ice growth in the Bellingshausen and Amundsen Seas, one of the few regions with lower-than-average ice extents in March. Antarctic sea ice has now been significantly above the satellite average level for 16 consecutive months."
"...with climate models we can clearly link this to rising greenhouse gas levels."
I'd say this might point toward a shift toward a possible ice age. What if the vortex grew in strength and then extended out from Antarctica? Also, seems the Acrtic polar vortex was all out of whack this year, bringing a really cold winter to the US, so the weather at the poles is looks like it is changing.