Rainfall was declining, while projections of further declines in rainfall were greater than first expected, Chris Mitchell of the government-backed Commonwealth Scientific and Industrial Research Organisation (CSIRO) told Reuters on Monday.  The region contains Perth, Australia's western capital and fourth biggest city with 1.5 million people, and also grows two of the country's most important crops, wheat and grapes.

The study forecast that rainfall in the area may fall by up to 20 percent by 2030 compared with levels between 1960 and 1990. The number of winter rain days was forecast to decrease by up to 17 percent, with the water run-off into catchments falling by between 5 and 40 percent, it said.

The changes might further increase by about 2085, with rainfall declining by between 5 and 34 percent and the number of winter rain days decreasing by up to 30 percent, it said. Observed temperature increases and winter rainfall decline in the region were unlikely to be due to natural climate variability alone, the study said.

"Our results show that that by 2030 there would be a rise in temperatures in all seasons and a decrease in winter rainfall," CSIRO scientist Bryson Bates said. "It's unlikely the observed warming is a result of natural climate variability alone," added Pandora Hope of the Bureau of Meteorology research centre.

Research would be stepped up into the causes and magnituide of climate change in Western Australia, Bates said. The study was conducted by the Indian Ocean Climate Initiative, a partnership of the state government of Western Australia, the commonwealth government-backed CSIRO, and the national weather bureau.

(Planet Ark, 02/04/2007)