Five teams using different approaches came to the same conclusion – the severe heat wave in Australia through much of 2013 and persisting into this year was “almost certainly a direct consequence of greenhouse gases released by human activity,” says the New York Times. “It is perhaps the most definitive statement climate scientists have made tying a specific weather event to global warming.” Their findings came from computer comparisons of what the climate would have been like with and without greenhouse gases released by human activity, “a type of research widely acknowledged to be imperfect.”
As far as the California drought, the Times said two out of three research groups found no clear evidence climate change had increased the odds of the arid weather. But they generally agreed the effects of the drought were worsened by global warming, it said.
The research, published as a supplement to the Bulletin of the American Meteorological Society is available here.