Australian heatwave shows man-made climate change, scientists say The extreme heatwave gripping southern Australia forced the suspension of matches at the Australian Open tennis tournament on Thursday, as temperatures soared to 42C in Melbourne and officials warned of escalating risks of bush fires and power outages. Tournament organisers implemented an extreme heat policy and stopped matches played on outer courts, which do not have retractable roofs. Temperatures are forecast to reach 44C in Melbourne, putting pressure on electricity networks struggling to cope with surging demand. Government officials have warned of health risks caused by the extreme heat amid reports of an increase in cardiac arrests. A third day of temperatures over 40C has focused attention on scientists" warnings that heatwaves are one of the clearest examples of man-made climate change and Canberra's recent decision to scrap a carbon tax introduced to curb emissions. An interim report published on Thursday by the Climate Council, a non-governmental group staffed by Australian scientists, found heatwaves in the country are becoming more frequent, lasting longer and the hottest days are becoming hotter. It blames increased greenhouse gas emissions for the intensity of the heatwaves. Australia has always had hot weather. However, climate change is loading the dice toward more extreme hot weather," said Professor Will Steffen, author of the report. The Climate Council was formed following a decision by Prime Minister Tony Abbott's government to scrap a formal state Climate Commission, which was set up to provide reliable information on climate change. Australia's second severe heatwave in a fortnight follows confirmation by the Bureau of Meteorology that 2013 was the hottest year on record. Average temperatures were 1.2C above the long-term average, breaking the previous record set in 2005 by 0.17C. "Rising temperatures in Australia are a signal of climate change that has emerged very clearly from recent analysis," said Peter Stott, head of climate monitoring at the UK Meteorological Office Hadley Centre. Last year's temperatures were a long way outside the envelope of variability that we would expect in the absence of climate change. Climate change is harder to detect unambiguously in regions such as northwest Europe where there is greater natural variability. "Temperatures in the Arctic have risen by more than those in Australia but the signal there is not as clear," added Mr Stott. Sarah Perkins, an expert on Australian climate extremes at the University of New South Wales, pointed out that the latest heatwaves were taking place in the absence of El Niño, the periodic warming of the tropical Pacific Ocean. "We usually expect to see hotter temperatures at higher frequencies during an El Niño phase, yet we've seen hot event after hot event when the modes of climate variability are not conducive to this," she said. When El Niño returns, heatwaves may become more severe - bad news for summertime events such as the Australian Open. "Today, 30 minutes after the match I could not walk," said Ivan Dodig, a Croatian tennis player on Wednesday. I was thinking I could maybe even die here. Extreme heat poses risks to humans and to wildlife. "When average conditions are exceeded over a period of time by continuously high night-time and daytime temperatures, heat stress becomes a critical factor in human survival and infrastructure resilience," said Alasdair Hainsworth, assistant director for weather services at the Australian Bureau of Meteorology. Fire chiefs have warned of the severe danger of bush fires on Friday when winds are due to pick up and temperatures remain extremely high. Authorities in Victoria said on Thursday that 1,000 fires had been reported over the past two days and 40 were still burning. Adelaide, the state capital of South Australia, is forecast to be the hottest city in the world with a temperature of 46C. Electricity demand has reached record levels prompting blackouts in some areas. Ten thousand homes lost power in Melbourne on Wednesday afternoon and the government in Victoria has warned that 100,000 properties may face power cuts in the next two days.