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New studies by CSIRO Oceanographers have shown greenhouse warming is likely to be greater than expected in the Southern Hemisphere.
Until now simulations of global climate change have consistently shown that warming in the Southern Hemisphere will be one third of the warming of the Northern Hemisphere.
The oceans act like a heat bank, or a thermal flywheel, that absorbs energy and so can slow down the rate of global warming.
"Theoretical work, new ocean observations and new modelling studies are all telling us that we have previously greatly overestimated the ability of the southern ocean to slow the warming process," said Dr Trevor McDougall, senior principal research scientist at CSIRO's Division of Oceanography.
The new studies have shown that the capacity of the oceans to delay global warming in the Southern Hemisphere is only half the capacity used in the present computer models to predict climate change.
"This means the Southern Hemisphere could become warmer far more quickly under an enhanced Greenhouse Effect than our current climate models indicate," said Dr McDougall.
The ocean contains many highly energetic eddies of approximately 100 kilometres in diameter, and the new work recognises that these eddies not only mix heat in the ocean, but they also cause movement towards the southern pole in the upper 1,000 metres of the ocean.
Due to the limitations of current computers, the ocean models used for climate research cannot directly include these eddy effects.
In ground-breaking work, Dr Trevor McDougall and his team has developed a more realistic method of modelling the effects of ocean eddies. The method has also reduced greatly the impact of several long-standing and well-known deficiencies of ocean models.
Dr McDougall said this work demonstrates that Australia cannot afford to act solely on the results of Northern Hemisphere scientific climate change programs.
It also points to the need to increase observations of ocean processes in the southern hemisphere, particularly in the coastal zone and Australia's Exclusive Economic Zone (EEZ).
The latest ocean modelling, funded by CSIRO and the Federal Government's National Greenhouse Research Program, was undertaken by Drs McDougall and Peter McIntosh, of the CSIRO's Division of Oceanography, Anthony Hirst of the Division of Atmospheric Research and Matthew England of the University of New South Wales School of Mathematics and was recently presented to an international conference of oceanographers in Hawaii.
For further information please contact:
Dr Trevor McDougall
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