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Imperfect storms

Reuters/Eduardo Munoz

That ridiculous heatwave really was caused by climate change.

Which one? Pick any heat wave, according to a new study, and there’s a greater than 80 percent chance that climate change was behind it.

If you have ever been reprimanded by some insufferable pedant (maybe me) for blaming the record-breaking heat on climate change, prepare to receive some validation. The paper, published this week in the Proceedings of the National Academy of Sciences, suggests you were likely right.

Lead author Noah Diffenbaugh and a team of researchers found that human-caused global warming has nudged up the thermostat on the hottest day, and hottest month, across more than 80 percent of the Earth. They also found we’ve also turned up the volume on the weather, increasing the likelihood of a record dry year in 57 percent of places observed.

Last year, the National Academies published a fat report on attributing extreme weather events to climate change. The report said that, although science can’t deliver an absolute verdict about what caused a specific heatwave or hurricane, it can tell us how much climate change boosted the likelihood or intensity of that event. In other words, science deals in probabilities, not absolute certainties. But as the science improves, with papers like this latest one, those probabilities get higher and higher.