West Australian drought linked to Antarctic snowfall

An ice core from Antarctica has uncovered a link between drought in Western Australia and increased snowfall in Antarctica.

Dr Tas van Ommen, a glaciologist with the Australian Antarctic Division, studied a 750 year old ice core from Law Dome in East Antarctica.

The results of the research by Dr van Ommen and co-author  Vin Morgan have recently been published in Nature Geoscience.

Law Dome

Law Dome, Antarctica. Photo by Tas van Ommen © Commonwealth of Australia

“The ice core shows how much snow fell at Law Dome each year, and we have compared the modern portion of that with meteorological records from Australia,” Dr van Ommen said.

“What we found was amazing. While we were noticing extra moisture in east Antarctica and increasing snowfall, we were seeing dry conditions over south-west Western Australia,” he said.

There has been a 15-20% decline in winter rainfall in south-west Western Australia since the late 1960s, and at the same time there has been a 10% increase in snowfall at Law Dome.

Dr van Ommen said it appears that a change in atmospheric circulation patterns off southern Australia is responsible.

Dr Tas van Ommen collecting ice core

Dr Tas van Ommen collecting an ice core at Law Dome in Antarctica. Photo by Joel Pedro © Commonwealth of Australia

“In the past three decades the strength of persistent high and low pressure systems off southern Australia have increased, directing more warm, moist air south towards the coast of Antarctica and dry, cold air north in winter,” Dr van Ommen said.

“This does not appear to be in the range of natural variability: we can see from the ice core that an event like the increased snowfall at Law Dome would only come along once every 38,000 years without some change in climate patterns and, given the connection we see with Western Australia, it would suggest that the drought is also not a natural event,” he said.

Dr van Ommen said the change may be due to human-induced atmospheric changes; from reductions in ozone and increased carbon dioxide in the atmosphere.

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