Australian Heatwave Is Linked Directly to Climate Change

Last year’s searing heat wave that scourged Australia’s already dry landscape was a direct result of human-caused climate change, according to five independent research groups.

The conclusion comes as part of a compilation of new reports from the American Meteorological Society that assesses extreme weather events during 2013 in a number of different places, including Europe, China, Japan, and the Korean Peninsula. In some cases—a South Dakotan blizzard and a mid-autumn Europe cyclone, for example—the researchers were able to rule out human factors. In others, they argue that manmade emissions merely increased the probability of abnormal atmospheric conditions.

But in the case of Australia’s 2013 heat wave, scientists from the five separate groups all reached the same conclusions: had our climate not been operating under the influence of greenhouse gases, it couldn’t have produced such sweltering conditions.

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A series of reports from the American Meteorological Society provides the first direct and causal link between manmade activity and a specific weather event.

Here’s Justin Gillis, writing for The New York Times:

The findings relied on computer analyses of what the climate would have been like in the absence of human-caused greenhouse emissions, a type of research widely acknowledged to be imperfect, and which often produces conflicting findings from different groups. But scientists said the results in this case were strengthened by the unanimity of the papers, written by veteran research teams scattered around the world.

“The evidence in those papers is very strong,” said Martin P. Hoerling, an American scientist with the National Oceanic and Atmospheric Administration who has often been skeptical of claimed links between weather events and global warming.

When those same computer models added back in the impacts of greenhouse gas emissions, they produced an upward swing in the likelihood of high temperatures—exactly what happened in Australia. This finding marks the first direct and causal link scientists have found between human-related activity and a specific weather event.

Until now, scientists have been hesitant to draw any immediate conclusions about the role of greenhouse gases in extreme weather events, making the combined results of these five studies all the more noteworthy.