The visit by Chinese Premier Wen Jiabao to Australia in early April brought back memories for CSIRO climate modeller, Wenju Cai, of the earliest exchanges between the two countries.

The 1983 accession of Bob Hawke as Australian Prime Minister proved to be a milestone in the life and times of Cai, as he is known to colleagues at CSIRO. A student at Amoy University in southern China, and with a passable grasp of English, Cai was among a group of students benefited from the Prime Minister drive to establish trade and cultural relations. In the first phase of cultural relations, Cai was invited to be included in the initial exchange of students, after acting as a translator for a collaboration program between the two countries,

It was a significant step for Cai, and for Australian science, the beneficiary of his climate modeling expertise. Twenty years on, Cai, from CSIRO Marine and Atmospheric Research, leads the Climate and Water component of the Water for a Healthy Country Flagship and also contributes to the Wealth from Oceans Flagship.

Cai and his colleagues are studying Australia-wide and Regional influences of climate change, with emphasis in three key areas:

• (a) development of foundational knowledge of Australia's climate baselines,

• (b) climate change impacts on Australia-wide baselines, and

• (c) predictability on seasonal and long-term time scales.

This research builds on and applies the mulit-institutional climate work already underway within CSIRO and partner organisations. The emphasis is on the application of fundamental climate science understanding and prediction to:

• Facilitate improved urban water supply systems

• Assist dryland grazing and agricultural practice; and

• Maximize opportunities for ecological systems management.
   

It is envisaged that as the Flagship grows the Australia-wide Climate and Water will expand to include

• Impact of extreme events on water system, and

• Impact on catchment stream flow and water quality.

Cai has contributed to the substantial advance of climate knowledge through his work here and overseas with agencies in Japan, Canada and the United States. He is lead author on some 40 science publications, and contributed to many more.

He has helped coordinate research in the Perth-based Indian Ocean Climate Initiative and the South East Australia Climate project, centred on the Murray Darling catchment and supported by the Murray - Darling Basin Commission, the Victorian Government, Land and Water Australia and CSIRO.

Wealth from Oceans Flagship

"I think of the influences on Australian climate as being like a three-headed dog.

"In the Pacific there is the El Nino Southern Oscillation, in the Indian Ocean a feature with similar characteristics to El Nino called the Indian Ocean Dipole and the Southern Annular Mode or Antarctic Oscillation.

"Between them, they control the circulation patterns in the ocean basins around Australia – vast eddy-like super gyres driven by the wind systems and that in turn have a bearing on the coastal systems of Australia," he said.

Papers by Cai in 2005 and 2006 and published in the Geophysical Research Letter provide an insight into two outcomes of this research –

• A link between ozone depletion over the Antarctic and an intensification of the super-gyre leading to a 20 per cent increase in the strength of the East Australian Current

• Warming of the western Tasman Sea east of Tasmania where temperatures recorded for more than 50 years at an offshore station near Maria Island have risen nearly two degrees, and will continue.

"Warming in the latitude around 40°S east of Tasmania is the greatest anywhere in the Southern Hemisphere and we believe that is the result of changes in ocean circulation," Cai says.

Those oceanic changes, when coupled with shifts in wind and pressure systems are influencing rainfall patterns across Australia. Water supply systems were established based on a set of climate baselines (annual total rainfall and the associated inflows) at a time when rainfall was higher than the present level, with water allocation strategies assuming stationary climate baselines. Climate variability and change over the past decades have overturned that assumption.

Science plans for the South East Australia Climate project will be detailed at the first science workshop in Melbourne on April 19 and 20 – a chance to get an insight into the research of Cai and his team.

Contact: Dr Wenju Cai, CSIRO Marine and Atmospheric Research
03 9239 4419 Wenju.Cai@csiro.au

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