The government has already made the unprecedented declaration that farmers will receive no irrigation water from July in Australia's most fertile region if the country's worst drought in a century continues.

Water restrictions have been imposed across the vast island continent and scientist Tim Flannery, named the 2007 Australian of the year for his pioneering environmental work, says the problem will only get worse.

Flannery said the drought meant two of Australia's largest cities, Brisbane and Adelaide -- home to a combined total of almost three million people -- would run out of water by the year's end unless the so-called "Big Dry" ended.

"We could see a catastrophic situation developing here by the end of the year. It's become a huge issue," Flannery told AFP.

"Even a year ago this would have been unthinkable. I think it's the most extreme and the most dangerous situation arising from climate change facing any country in the world right now.

"We have a situation where, if there are no flows in the Murray-Darling (river system), Adelaide, a city of one million people, has only 40 days' worth of water left in storage.

"If we don't get any rain this year Adelaide and Brisbane may be facing diabolical problems."

The drought, which has lasted a decade in parts of the country, has slowed Australia's overall economic growth by an estimated 0.75 percent as crops have fallen 62 percent.

The impact on rural communities has been devastating. Many farmers have been forced off the land and counselling services have reported unusually high levels of suicide in rural areas.

Children have water conservation messages drummed into them from an early age at school and householders face hefty fines, or can even have their water disconnected, if they are found to be wasting the precious resource.

The impact of climate change is also evident off Australia's northeast coast where the Great Barrier Reef -- the world's largest living organism -- has been badly damaged by bleaching linked to rising ocean temperatures.

The government is also concerned that Australia's tourism industry, which earns billions of dollars a year, will be hit by "jet guilt" -- a reluctance by holidaymakers to take the heavily polluting, long-haul plane flights that are the only practical way to reach Down Under.

Authorities are also considering culling some of the million-plus feral camel population after dromedaries "mad with thirst" rampaged through a remote desert community.

Authorities are also considering culling some of the million-plus feral camel population after dromedaries "mad with thirst" rampaged through a remote desert community.

Researchers warn the drought could drive Australia's iconic koalas to extinction within a decade.

The scale of the problem hit home for many Australians in April when Prime Minister John Howard said there would be no water for farms in the Murray-Darling river basin unless the drought broke soon.

Covering more than one million square kilometres (400,000 square miles) in the southeast of Australia, the Murray-Darling basin is the country's largest river system, almost three times bigger than Japan and four times larger than Britain.

It is Australia's rural powerhouse, producing more than 40 percent of the nation's agricultural produce, worth 10 billion dollars (8.3 billion US) a year.

The Murray-Darling supports half the nation's sheep flock, a quarter of the cattle herd and three-quarters of irrigated land.

While Howard acknowledged the situation was "grim," he said there was no definitive proof the drought was caused by climate change.

However, Murray-Darling Basin Commission chief Wendy Craik had no doubts.

"Well, we'll never prove it's climate change until after the event but a lot of farmers have said this drought has the fingerprints of climate change all over it," she said.

Flannery also dismissed climate change sceptics and said he would continue using his position as Australian of the year to push for action on the issue.

"Any scientist working in the field would recognise the issues," said Flannery, whose book on climate change, The Weather Makers, has made the list of New York Times best-sellers.

"I feel that the people of Australia gave me the award because they wanted me to be a voice for them on environmental issues and that's what I'll continue to be."

Victorian farmer Marshall Rodda was unsure about whether global warming was behind the drought that has dried up his land, saying he had more immediate concerns.

"We just want it to rain," he told AFP. "Rain long and rain hard."

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