A new report by Australia's top scientists predicts that the country will be hit by a 10-fold increase in heatwaves and that droughts will almost double in frequency and become more widespread because of climate change.

The scientific projections envisage rainfall continuing to decline in a country that is already one of the hottest and driest in the world. It says that about 50% of the decrease in rainfall in south-western Australia since the 1950s has probably been due to greenhouse gases.

Yesterday, Australia's agriculture minister, Tony Burke, described the report as alarming and said: "Parts of these high-level projections read more like a disaster novel than a scientific report."

The analysis, commissioned by the government as part of a review of public funding to drought-stricken farmers, was published days after another report, by Professor Ross Garnaut, warned that Australia had to adopt a scheme for trading greenhouse gas emissions by 2010 or face the eventual destruction of sites including the Great Barrier Reef, the wetlands of Kakadu and the nation's food bowl, the Murray-Darling Basin.

The prime minister, Kevin Rudd, who swept to victory on a green agenda last November, said the analysis by the Bureau of Meteorology and the Commonwealth Scientific and Industrial Research Organisation was "very disturbing".

The reports will put pressure on him to act swiftly on his pledge for Australia to lead the world in tackling polluters. However, the rising cost of living has dented his government's popularity and his plans for a carbon trading scheme have begun to unnerve voters and industry. Rudd has acknowledged that tough debate lies ahead and has said the government will map out its policy options this month.

Yesterday's report revealed that not only would droughts occur more often but that the area affected would be twice as large as now. The proportion of the country having exceptionally hot years could increase from 5% each year to as much as 95%, according to the projections.

The report says rainfall in Australia has been declining since the 1950s and about half of that decrease is due to climate change. It says the current thresholds for farmers to claim financial assistance are out of date because hotter and drier weather will become the norm.

Burke said it was clear that the cycle of drought was going to be "more regular and deeper than ever before". He added: "If we failed to review drought policy, if we were to continue the neglect and pretend that the climate wasn't changing, we would be leaving our farms out to dry."

Parts of Australia are now in a sixth year of drought, and the report coincided with an announcement that there has been a worsening of the drought in New South Wales. Some 65% of the state is affected, an increase of more than 2.3% on last month, although opinion is divided on whether it can be attributed to climate change.

A plague of locusts is also threatening crops in the state, with farmers on 900 farms reporting finding locust eggs. The government plans to fight the infestation with aerial spraying before the eggs hatch.