56 Studies Confirm: Global warming to increase road rage & fights at baseball games! Is WaPo’s Chris Mooney serious?! Is Mooney serious? Includes charts on ‘retaliatory beanballs’ by MLB pitchers! ‘There’s a surprisingly strong link between climate change and violence’
'For 1 degree Celsius of warming, he'd expect about a 1 percent increase in interpersonal conflicts, a category that includes crimes like assault and robbery but also road rage and fights at baseball games.'
Mooney: 'For instance, one of the studies cited in the new meta-analysis is a 2011 paper published in Psychological Science (discussed in more depth here) showing a relationship between hot temperature days and the number of retaliatory beanballs thrown by Major League Baseball pitchers. The figure below shows their results in more detail:

The study's lead author Richard Larrick, a professor at Duke's Fuqua School of Business, explained in an e-mail the psychological research linking heat with shows of aggression.
[More on WaPo's Chris Mooney's statistical silliness: http://wmbriggs.com/blog/?s=mooney
It is important to emphasize the strength of this conclusion: It emerges from multiple studies, the vast majority of which point to the same takeaway conclusion. For example, across 19 studies, Burke and his colleagues found 24 separate estimates of the relationship between temperature changes and various kinds of conflict outcomes, and in every case, that relationship was positive. “The probability of getting 24 positive values if there was in fact no relationship between temperature and conflict … is less than 1 in 100 million,” Burke said in an e-mail. “It’s like flipping a coin 24 times and getting heads each time.”
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Temperature-violence relationship is not deterministic. In their meta-analysis, Burke and his colleagues liken the situation to “the rise in car accident rates during rainy days” — the rain ups the risk of accidents overall, but each accident is still contingent on the individual situation and choices (and mistakes) of the drivers involved.
Similarly, warmer temperatures seem to shift the overall background risk for violent conflict — but whether someone commits a violent act remains dependent upon the specific circumstances and the individual.
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It is important to underscore that the temperature-violence relationship is not deterministic. In their meta-analysis, Burke and his colleagues liken the situation to “the rise in car accident rates during rainy days” — the rain ups the risk of accidents overall, but each accident is still contingent on the individual situation and choices (and mistakes) of the drivers involved.
Similarly, warmer temperatures seem to shift the overall background risk for violent conflict — but whether someone commits a violent act remains dependent upon the specific circumstances and the individual.
So the relationship is statistical — but that doesn’t make it any less real. “We believe there is overwhelming evidence of a strong relationship between changes in temperature in particular, and various types of human conflicts,” says Burke.