Antarctic wind vortex may be strengthened by greenhouse gases

New Scientist : Warming of the air over Antarctica has been slower than in most of the rest of the world. The prevailing explanation is that the winds spinning around the continent have gotten stronger and are keeping out the warmer air. Earlier work ties the strengthening winds to the ozone hole. However, an analysis of ice cores by Nerilie Abram of the Australian National University and her colleagues identifies the 1940s, a period before the growth of the ozone hole, as the point when the wind strength began to grow. Using several historical atmosphere simulations, Abram’s team found a connection between the wind speeds and greenhouse gas emissions. As the wind strength has increased, the size of the vortex has shrunk, exposing the edges of Antarctica to warmer air and shifting rain away from Australia. But the ozone hole is expected to heal, which will weaken the vortex and allow more warming.