Ozone Hole Fix Equals Warmer Antarctica

A full recovery of the stratospheric ozone hole could modify climate change in the Southern Hemisphere and even amplify Antarctic warming, according to scientists from the University of Colorado at Boulder, the National Oceanic and Atmospheric Administration and NASA.

The study authors calculated that when stratospheric ozone levels return to near pre-1969 levels by the end of the 21st century, large-scale atmospheric circulation patterns now shielding the Antarctic interior from warmer air masses to the north will begin to break down during the austral summer. The circulation patterns are collectively known as a positive phase of the Southern Annular Mode, or SAM.

The scientists found that as ozone levels recover, the lower stratosphere over the polar region will absorb more harmful ultraviolet radiation from the sun. This could cause air temperatures roughly 6 to 12 miles above Earth’s surface to rise by as much as 16 degrees Fahrenheit, reducing the strong north-south temperature gradient that currently favors the positive phase of SAM, said the research team.

The supercomputer modeling effort also indicated that ozone hole recovery would weaken the intense westerly winds that currently whip around Antarctica and block air masses from crossing into the continent’s interior. As a result, Antarctica would no longer be isolated from the warming patterns affecting the rest of the world.

The seasonal shift in large-scale circulation patterns could have repercussions for Australia and South America as well. Other studies have shown that the positive phase of SAM is associated with cooler temperatures over much of Australia and increased rainfall over Australia’s southeast coastline.

During late spring and early summer, the positive phase of SAM also is associated with drier conditions in South America’s productive agricultural areas like Argentina, Brazil, Uruguay and Paraguay, said Perlwitz. If ozone recovery induces a shift away from a positive SAM, Australia could experience warmer and drier conditions while South America could get wetter, she said.

Science Daily