After the US baked in a searing heatwave and as Russia mourns the deaths of more than 100 flood victims, scientists have produced what they say is groundbreaking research linking climate change to recent extreme weather.
Global warming “significantly” increased the odds of some of last year’s most unusual weather, including the brutal Texas drought and the freakishly warm November in Britain, according to findings released Tuesday alongside the latest “state of the climate” report in the Bulletin of the American Meteorological Society.
It probably also played a part in unusual temperatures across western Europe in 2011, a year that was almost 1.5°C warmer than what could be attributed to weather patterns alone.
But the fingerprint of human-induced climate change was not evident in other weather disasters such as the devastating Bangkok floods late last year, says the peer-reviewed research, which found the rain that caused them was not that extreme.
And it is still too early to be absolutely sure about a link between climate change and the latest US heatwave, which has shattered more than 2,000 temperature records in the space of a week, researchers said, nor the apparently endless stretch of rain behind the UK’s sodden summer.
“We’re not necessarily seeing a clear human influence on every single event we’re looking at,” said the UK Met Office’s Dr Peter Stott, co-editor of the new research that attempts to explain what links, if any, can be made between climate change and volatile recent weather.
Dr Stott said the findings were significant because they were being published within months of extreme weather – something that can sometimes take a decade – and because it allowed scientists to say more about the impact of climate on specific weather events, which most have been reluctant to do.
“This report really is groundbreaking in the sense that we’re applying attribution science to recent extreme weather events,” he told reporters in London.
“In the past you may have heard: ‘Well it isn’t possible to attribute an individual extreme weather event’, and the science really has moved on now.
“The way that it’s moved on is the realization that we can look at how the odds of events have changed ... whether the likelihood of having an extreme weather event has increased or decreased.”
Still, the timeliness of the research comes at the expense of its breadth. It only covers six events: droughts in Texas and east Africa; Thailand’s floods; higher European temperatures; the UK’s warm November and its “big freeze” in the 2010-11 winter.
“The idea here is to apply attribution science at the time when people are asking questions about what’s actually happening,” said Dr Stott. “The idea hopefully is this will become a regular thing, an annual report, but it is stretching the science. We are attempting to do this quickly and therefore we haven’t been able to be comprehensive.”
The scientists found the Texas drought was about 20 times more likely than it would have been in the 1960s with similar weather patterns, while the warm UK November was about 60 times more likely than in the same decade.
While Britain had its second coldest December on record in 2010, the research suggested there had been a reduction in the odds of such a freezing winter.