Humans play role in Australia’s “angry” hot summer

Human influences through global warming are likely to have played a role in Australia's recent “angry” hot summer, the hottest in Australia’s observational record, new research has found.

The research led by Centre of Excellence researchers at the University of Melbourne, has shown that global warming increased the chances of Australians experiencing record hot summers such as the summer of 2013, by more than five times.


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This animation shows how the probability of extreme temperatures has changed in Australia over the past century or so. Extremely hot temperatures are more likely while extremely cold temperatures have declined.


Lead author, Dr Sophie Lewis from the University of Melbourne and the ARC Centre of Excellence for Climate Systems Science said the study showed it was possible to say with more than 90 per cent confidence, that human influences on the atmosphere dramatically increased the likelihood of the extreme summer of 2013.

“Our research has shown that due to greenhouse gas emissions, these types of extreme summers will become even more frequent and more severe in the future,” she said.

The study Anthropogenic contributions to Australia’s record summer temperatures of 2013 has been published today in the international scientific journal Geophysical Research Letters.

The study used climate observations and more than 90 climate model simulations of summer temperatures in Australia over the past 100 years.

Professor David Karoly, a co-author on the paper said the observations, coupled with a suite of climate model runs comparing human and natural influences in parallel experiments, indicated we have experienced a very unusual summer at a time when it was not expected.

This map shows how mean temperatures skewed upwards in Australia during the 2012/13 summer.


“This extreme summer is not only remarkable for its record-breaking nature but also because it occurred at a time of weak La Niña to neutral conditions, which generally produce cooler summers,” he said.

“Importantly, our research shows the natural variability of El Niño Southern Oscillation is unlikely to explain the recent record temperatures.”

This analysis of the causes of the record 2013 Australian summer is one of the fastest ever performed worldwide for a significant climate event.

This fast-response analysis was made possible because data from many existing climate models and observations were made available through Centre of Excellence collaborations with CSIRO, the Bureau of Meteorology and the National Computational Infrastructure in Australia.

“The new data resource means scientists are able to work on understanding and addressing the problems of extreme climate events sooner,” Professor Karoly said.

The researchers are now turning their attention to other recent extreme climate events.


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