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Antarctic snow linked to WA dry

Stuart Gary

Story Added : 08th February 2010

Scientists have discovered a link between the ongoing drought in the south western corner of Australia and increased snowfall in parts of Antarctica.

Dr Tas van Ommen of the Australian Antarctic Division (AAD) says ice core samples taken from Law Dome in East Antarctica show an unusual and consistent increase in snowfall since the late 1960s.

Reporting in Nature Geoscience van Ommen says, "after examining 750 years worth of samples, the increase is well above the normal sort of variability one expects."

The work was part of efforts to better understand Antarctica's climate history.

van Ommen and AAD colleague Dr Vin Morgan found the cause was a pattern of atmospheric circulation that brings warm, moist air from the Tasman Sea near New Zealand to East Antarctica.

He says "further research found this same pattern was part of a larger flow recirculating dry, cool air from the Antarctic to south western Australia."

And a check of Western Australian climate records showed a very strong correlation.

"The more it snowed at Law Dome, the more intense the drought became in the south west of Western Australia."

van Ommen says "the cause appears to be what's called the 'wave three pattern' in the high latitude atmosphere which is associated with the three southern hemisphere ocean basins, the Pacific, Atlantic and Indian.

"But as to why the wave three pattern has strengthened over the last 30 years, that's still a mystery," says van Ommen.

Climate change

Climate change models that factor in increases in CO2 emissions and ozone depletion appear to produce a similar result, a finding backed up by climatologist Tim Cowan of the CSIRO.

"Not only has the paper established a nice link between the snowfall and drought, but the climate models show increases in greenhouse gases and an ozone reduction can account for about half the rainfall decline in Western Australia's southwest," says Cowan.

"We have seen a real step change in rainfall levels in Western Australia's south west, which is very dramatic and concerning."

Cowan says, "based on climate models projections for future, there's a high probability that south west Western Australia will get even dryer.

Story Added by ABC.
Date Added : 08th February 2010

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