Australia Faces Future Of Heatwaves And Drought
Leigh Dayton, Science writer
18jan07


EVIDENCE from fossil corals collected in the Indian Ocean west of Sumatra suggest that Australia and Indonesia may face a future of scorching heat waves and severe long-running droughts.

This will be all thanks to the intensification of Asia's monsoon rains, according to Australian, Indonesian, US and Chinese researchers who reported their findings overnight in the journal Nature.

“This is a good example of the big connections through the global climate system,” project leader Mike Gagan said.

“You can't change one thing without changing another,” said Dr Gagan, a paleoclimatologist at the Australian National University in Canberra.

Geochemists Jonathan Overpeck and Julie Cole, of the University of Arizona in Tucson, say the report is sobering.

“Rural livelihoods and natural resources will thus be at greater risk as drought undercuts regional food supplies and stokes wildfires that also generate exceedingly poor air quality in the region,” they wrote in an accompanying piece in Nature.

Along with team mates - including former ANU doctoral student Nerilie Abram, now with the British Antarctic Survey in Cambridge - Dr Gagan reconstructed 6500 years of past climate, presevered in the coral like a marine version of tree rings.

When combined with recent climate records, the results revealed a complex link between monsoons, droughts and even the El Nino/Southern Oscillation (ENSO) and a similar flip-flopping system called the Indian Ocean Dipole (IOD).

The group discovered that when monsoons were strong, they drove powerful winds across the Indian Ocean, cooling the surface water and thus increasing the drought-inducing effects of the Dipole.

What cranked up monsoons were periods of increased heating of the land.

“They were from natural causes in the past and potentially unnatural causes in the future,” explained Dr Gagan, pointing to increased solar radiation and global warming.

Moreover, he said when an El Nino coincided with a “dipole event” the result was a “very bad” drought for Indonesia and southwestern Western Australia, Victoria and western NSW. ”Even Canberra dries out.”

Dr Gagan added that while past events occurred over a thousand years or so, future changes could be abrupt, making adaptation difficult.

“We could see some dramatic changes within a human lifetime,” he predicted. “It's astonishing, but it's all connected.”


Original article: The Australian
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