Scientists have a hunch rising temperatures due to human activity are making fire and flood more likely

Scientists are reluctant to link ­individual weather events to global warming, because natural variability will always throw up extreme events. However, they say that climate change loads the dice, and can make severe episodes more likely.

Some studies have started to say how much global warming contributed to severe weather. Experts at the UK Met Office and Oxford University used computer models to say man-made climate change made the killer European heatwave in 2003 about twice as likely. In principle, the technique could be repeated with any extreme storm, drought or flood – which could pave the way for lawsuits from those affected.

Bob Brown, a senator who leads the Australian Greens, said the bushfires showed what climate change could mean for Australia.

"Global warming is predicted to make this sort of event happen 25%, 50% more," he told Sky News. "It's a sobering reminder of the need for this nation and the whole world to act and put at a priority our need to tackle climate change."

Models suggest global warming could bring temperature rises as high as 6C for Australia this century, if global emissions continue unabated, with rainfall decreasing in the southern states and increasing further north. As if to demonstrate that, Queensland, in the north, is currently experiencing widespread flooding after rainfall of historic proportions.

More than 60% of Queensland has been declared a disaster zone in the worst floods for more than 30 years. Some 3,000 homes have been affected, and the main highway between Cairns and Townsville has been cut off.

Roger Stone, a climate expert at the University of Southern Queensland, said: "It certainly fits the climate change models, but I have to add the proviso that it's very difficult, even with extreme conditions like this, to always attribute it to climate change."

The fires and floods come as politicians gear up to negotiate a new global deal to combat climate change, to replace the Kyoto protocol. Australia plans a comprehensive carbon trading scheme, but green campaigners last year accused Kevin Rudd's government of a "betrayal" when it pledged to reduce emissions by a modest 5-15% by 2020.

Professor Mark Adams, from the Bushfire Cooperative Research Centre, said the extreme weather conditions that led to the bushfires are likely to occur more often.

"The weather and climatic conditions recently don't augur well for the future. Bushfires are an important and going to be ever-present part of the landscape," he said.

Australia is in the grip of the worst drought in a century, which has stretched for more than seven years in some areas and has forced restrictions on water use in the country's big cities.

A government-commissioned report on climate change last year warned that exceptionally hot years, which used to occur once every 22 years, would occur every one or two years, virtually making drought a permanent part of the Australian environment.