They attribute the phenomenon to global warming and loss of the ozone layer over Antarctica.

"This is a very serious situation that we're probably not confronting as full-on as we should," Dr James Risbey of the Center for Dynamical Meteorology and Oceanography at Melbourne's Monash University told Reuters yesterday.

"There has been real added impetus here in Australia to try to study (the wind vortex) because we've been faced with an almost precipitous rainfall decline, particularly in the southwest of Western Australia," Risbey said.

Australia, one of the world's top agricultural supply nations, has just been through its worst drought in 100 years.

Risbey and other Australians are part of an international band of scientists and meteorologists focusing on the vortex as an explanation for declining rainfall.

Rainfall has declined by nearly 20 percent in the past seven years over parts of southwestern Western Australia, through to Victoria and into southern New South Wales state, Risbey said.

At the same time, temperatures have been rising in Australia by about one degree Celsius over the past 50 years, requiring more rain to fall just to keep the status quo.

SPINNING FASTER

Australian scientists from the Bureau of Meteorology, the Commonwealth Scientific and Industrial Research Organization (CSIRO) and Monash University are working with the U.S. Office of Oceanic and Atmospheric Research and the British Antarctic Division on the Antarctic vortex.

Focusing on the vortex for only the past few years, they have quantified increased velocity of the wind spin by measuring pressure differences between high latitudes over the Antarctic continent and mid latitudes in the Southern Ocean near Australia.

A cooling polar area and warming elsewhere is spinning the vortex faster, which in turn pulls winds and pressure belts that deliver Australia's winter and spring rains southward.

Australia's 2002/03 drought, the worst in 100 years and the cause of shortages of a wide variety of some of the world's largest supplies of bulk farm foods, was too extensive to blame on the Antarctic vortex.

But a long-standing drought in the southwest corner of Western Australia state could be a foretaste of more extensive drought yet to come in Australia, Risbey said.

Most worrying is that this could be more or less permanent, scientists say.

Water resource managers were already treating the rainfall decline in southwest Western Australia as permanent. Melbourne was now in a seven-year drought, while New South Wales has had declining rainfall for the past 50 years or so, Risbey said.

"It is consistent with...the polar vortex," he said.

Scientists say Australian agriculture would be able to cope with a 15 percent to 20 percent drop in rainfall, although farmers may not agree.