People keep cool at Brighton Beach on January 14, 2014 in
Melbourne, Australia. (Photo by Craig Sillitoe/Getty
Hotter days and longer heatwaves will occur in Australia
more frequently and earlier in the year, a report says.
And it will be decades before extreme temperatures stop
rising due to the effects of human-induced climate change,
one of the co-authors of the Australian Heatwaves report,
Professor Will Stefan of the Climate Council, says.
Heatwaves are occurring up to two weeks earlier than
previously recorded, are lasting longer and the number of
record hot days has doubled in the last 50 years, the report
Scientists define a heatwave as more than three consecutive
days where the temperature is in the top 10 per cent of days
for that time of year, as well as being hotter than the
During the past decade there were three times as many hot-day
records as there were cold, Prof Stefan said.
"That's virtually impossible to happen on the grounds of
natural variability alone," he told reporters.
"What's behind this? The physics is really, really clear. The
amount of greenhouse gases in the atmosphere is going up."
Co-author and heatwave expert Dr Sarah Perkins said "it is
clear" heatwaves are becoming more savage and are lasting
"This summer and last summer have been characterised by
extreme temperatures a lot of which have been record
breaking," she said.
Extended heatwaves will have significant negative impacts on
health and infrastructure, co-author Professor Lesley Hughes
"Heatwaves have been dubbed the silent killer," she said.
About 1000 people in Australia, generally elderly or
children, die each year due to heatwaves.
In the 2003 European heatwave about 70,000 people died and in
Russia in 2010 more than 50,000 were killed by extreme heat.
Heatwaves also damage infrastructure, Prof Hughes said.
Roads can melt, train and tram tracks can buckle and
over-stretched electricity networks can black out.
The final report is due out in late February.