Solving the mystery of why rainfall has declined so much in Australia's most heavily populated region - its eastern coastline - will be the focus of a major new research effort at UNSW.

Two of the nation's top climate scientists, Professor Matthew England and Professor Andy Pitman, are joining forces in a bid to understand the phenomenon in the hope of being able to predict whether worse, or better, is to come.

"Virtually the whole of the eastern coastline, from Cairns in the north down to Melbourne, has seen an incredible decline in rainfall in recent decades," says Professor England, who with Professor Pitman will jointly head the new UNSW Climate Change Research Centre.

"Compared with the relatively wet years of the 1950s, rainfall over the last 10 years has fallen by 300 to 400mm on average. Places that used to receive 1,300 or 1,400mm now only get 1,000mm.

"The consequences are painfully apparent for about half of the nation's population, especially in the major urban water supply problems now facing Brisbane, Sydney and Melbourne.

"We recently had a round-table of Australia's leading climate-change researchers and this emerged as the biggest unknown issue among the many major changes in rainfall patterns across Australia in recent decades."

The continent's south-west and Tasmania have become drier as a result of rain-bearing low-pressure systems shifting further south, by about five degrees in latitude.

It is thought that higher evaporation rates from the Indian Ocean to the north-west of the continent, combined with air pollution from Asia - mainly China - explain why the western deserts have received more rain. Likewise, parts of northern Australia have become wetter as a result of greater ocean evaporation. [see graphic]

"But we all agreed that the east coast issue is the key one we urgently need to understand better, especially if we want to predict what's going to happen in the future."

Professor Pitman, who has resigned from Macquarie University to join the UNSW initiative, notes that climate of New South Wales has been relatively poorly explored, and the project hopes to tackle that problem in particular.

"A major effort has been under way in Australia for many decades to understand the greenhouse effect, natural climate variability and other related processes, including changes in land-cover," Professor Pitman says.

"But this effort has been focussed on the southern states - mainly Victoria - and on south-west Western Australia, due to a major Western Australian government initiative.

"The vital role the northern monsoon plays in Australian climate has also been carefully researched by CSIRO, the Bureau of Meteorology and various university groups.

"Caught in the middle, our understanding of the climate of NSW has major gaps. For example, we do not know in detail the mechanisms that cause climate variability over NSW, nor why the rain-bearing low-pressure systems that re-fill our coastal dams, vary greatly year-by-year.

"We do not know why we are in such a severe drought, nor if this is natural or significantly enhanced through human activities via global warming.

"The initiative that UNSW has launched provides a world-class team of scientists who will provide a focus, a critical mass, to build our understanding of NSW climate.

"Through its strong national and international links to the world's leading climate groups, the UNSW team will provide a catalyst to accelerate climate research in NSW and re-position the State as a national leader in climate science."


Media contact:
UNSW Faculty of Science, Bob Beale 0411 705 435