Parched: Australia faces collapse as climate change kicks in

Geoffrey Lean and Kathy Marks report on the worst heatwave in the country's history

Leaves are falling off trees in the height of summer, railway tracks are buckling, and people are retiring to their beds with deep-frozen hot-water bottles, as much of Australia swelters in its worst-ever heatwave.

On Friday, Melbourne thermometers topped 43C (109.4F) on a third successive day for the first time on record, while even normally mild Tasmania suffered its second-hottest day in a row, as temperatures reached 42.2C. Two days before, Adelaide hit a staggering 45.6C. After a weekend respite, more records are expected to be broken this week.

Ministers are blaming the heat – which follows a record drought – on global warming. Experts worry that Australia, which emits more carbon dioxide per head than any nation on earth, may also be the first to implode under the impact of climate change.

At times last week it seemed as if that was happening already. Chaos ruled in Melbourne on Friday after an electricity substation exploded, shutting down the city's entire train service, trapping people in lifts, and blocking roads as traffic lights failed. Half a million homes and businesses were blacked out, and patients were turned away from hospitals.

More than 20 people have died from the heat, mainly in Adelaide. Trees in Melbourne's parks are dropping leaves to survive, and residents at one of the city's nursing homes have started putting their clothes in the freezer.

"All of this is consistent with climate change, and with what scientists told us would happen," said climate change minister Penny Wong.

Australia, the driest inhabited continent on earth, is regarded as highly vulnerable. A study by the country's blue-chip Commonwealth Scientific and Industrial Research Organisation identified its ecosystems as "potentially the most fragile" on earth in the face of the threat.

Many factors put Australia especially at risk. Its climate is already hot, dry and variable. Its vulnerable agriculture plays an unusually important part in the economy. And most people and industry are concentrated on the coast, making it vulnerable to the rising seas and ferocious storms that come with a warmer world.

Most of the south of the country is gripped by unprecedented 12-year drought. The Australian Alps have had their driest three years ever, and the water from the vast Murray-Darling river system now fails to reach the sea 40 per cent of the time. Harvests have fallen sharply.

It will get worse as global warming increases. Even modest temperature rises, now seen as unavoidable, are expected to increase drought by 70 per cent in New South Wales, cut Melbourne's water supplies by more than a third, and dry up the Murray-Darling system by another 25 per cent.

As Professor David Karoly, of the University of Melbourne, said last week: "The heat is unusual, but it will become much more like the normal experience in 10 to 20 years."