Australias killer bushfires have their origins in Indian Ocean

March 25th, 2009 - 1:21 pm ICT by ANI  

Sydney, March 25 (ANI): Climate experts have uncovered a link between the Indian Ocean Dipole (IOD) and the killer bushfires in Australia.

Found by Dr Wenju Cai and Tim Cowan, of CSIROs Marine and Atmospheric Research, the link indicates that a weather pattern centred on the Indian Ocean may provide an early warning system for major bushfires in southern Australia.

According to a report by ABC News, 11 of 16 major bushfires in Victoria since 1950 have been preceded by what is known as a positive IOD event.

Cai said that an unprecedented three consecutive positive IOD events preceded Februarys devastating Black Saturday bushfires.

The IOD refers to temperature fluctuations in the east and western Indian Ocean.

In its negative phase, the IOD brings cool water to the ocean west of Australia and warm water to the north, leading to winds that bring rain-bearing air over the continent.

In the positive phase, water temperatures are reversed and less rainfall travels to Australia, particularly to Victoria where the negative IOD provides winter and spring rains.

As part of their research, Cai and Cowan recorded changes in the IOD using Argo floats, robotic devices that measure the subsurface ocean temperature.

They found the IOD was in an unprecedented positive state for three consecutive years leading up to 2009.

They said that this preconditioned the environment to the extent that it was almost inevitable the bushfires, which claimed more than 200 lives, would occur.

If you look at the accumulative soil moisture in Victoria, its unprecedented, its never been so dry, said Cai.

The researchers also found an IOD link to the Ash Wednesday bushfires of February 1983, with a positive event reducing rainfall during the winter of 1982.

According to Cai and Cowan, climate change projections show the frequency of positive IOD events will increase in the future.

Almost all climate models say under climate change we are going to have an Indian Ocean warming pattern, said Cai.

That means it has to be manifested in either more frequent positive IOD events or higher intensity positive IODs, he added. (ANI)

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