As the old saying goes, as temperatures rise, tempers flare. That adage also applies to the effects of global warming on the human condition.

Researchers at the National Bureau of Economic Research culled through volumes of studies on the effects of climate change and came up with 55 reports they found valid in linking increases in violence with rising global temperatures.

The increases ranged from personal conflicts (domestic violence, road rage, assault, murder, and rapes) to country or group conflicts, including riots, ethnic violence, invasions, gang violence and civil wars. Even the incidence of beanballs in Major League Baseball games was shown to have increased with the outside temperature.

“We find that deviations from moderate temperatures and precipitation patterns systematically increase the risk of conflict, often substantially, with average effects that are highly statistically significant,” the researchers wrote.

In some parts of the world, temperature bumps could lead to serious increases in violence. A 1.8 degrees Fahrenheit rise in Africa could translate into a 20% increase in civil conflict on the continent.

The results were consistent throughout the research. In 19 of the studies, Stanford’s Marshall Burke and his fellow researchers found 24 instances when temperature positively affected conflict. “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 told The Washington Post. “It’s like flipping a coin 24 times and getting heads each time.”

-Noel Brinkerhoff

To Learn More:

There’s a Surprisingly Strong Link Between Climate Change and Violence (by Chris Mooney, Washington Post)

Climate Change and Rising Violence Are Linked, According To 55 Scientific Studies (by Jeff Spross, ThinkProgress)

Climate and Conflict (by Marshall Burke, Solomon M. Hsiang and Edward Miguel, National Bureau of Economic Research) (abstract)

Pentagon Devises Strategy for Responding to “Immediate Risk to National Security”—Climate Change (by Noel Brinkerhoff, AllGov)

U.S. Military Plans Policy Shift in Response to Anticipated National Security Threats Caused by Climate Change (by Noel Brinkerhoff, AllGov)