Here's one possible consequence of global warming you weren't expecting: A controversial new study predicts that as temperatures rise, so will crime rates. By 2099, rising heat could have caused 22,000 additional murders, according to the research. Published this month in the Journal of Environmental Economics and Management, the study examines historical crime and temperature data to demonstrate that hotter temperatures could cause an increase in all sorts of crimes.
The study author, Matthew Ranson, an economist at consulting firm Abt Associates, writes in the study abstract that his results prove that temperature has a strong impact on criminal behavior.
Between 2010 and 2099, climate change will cause an additional 22,000 murders, 180,000 cases of rape, 1.2 million aggravated assaults, 2.3 million simple assaults, 260,000 robberies, 1.3 million burglaries, 2.2 million cases of larceny, and 580,000 cases of vehicle theft in the United States.
Although in percentage terms, the increase doesn't seem gigantic — 2.2 percent for murder, for example, over a very long period of time — the actual human cost is staggering when you look at the raw numbers. Not to mention the social cost of these additional crimes, which could run as high as $115 billion.
To reach his conclusion, Ranson combined data from the FBI Uniform Crime Reporting database with data from the U.S. National Climatic Data Center’s Global Historical Climatology Network Daily, which has figures on 2997 U.S. counties over a 30-year period. He also used climate projections from 15 global circulation models.
So, what exactly is it about warmer temperatures which might bring out the criminal in us? Well, according to Ranson, it depends on the type of crime.
[P]roperty crimes, especially burglary and larceny, initially tend to increase as the weather warms but then level off once temperatures reach about 50 degrees. This suggests that cold weather may create obstacles to committing these types of crimes—Ranson cites closed windows, for example—obstacles that disappear when it's warmer outside.
By contrast, the relationship between violent crime and temperature appears to be highly linear—as temperatures keep rising, so does the number of crimes. According to Ranson, this pattern supports the idea that "warmer temperatures increase the frequency of social interactions, some small percentage of which result in violence." In other words, you're more likely to mug someone if it's warm enough to leave your house.
In the research, Ranson draws on previous studies that have linked high temperatures with increased aggression.
However, other experts warn against taking his findings too literally. Andrew Holland, Senior Fellow for energy and climate at the American Security Project, told told Mother Jones that while Ranson's study was an "interesting mathematical exercise," he's not sure it's any more than that.
"Just like any war has many reasons for starting, any crime has many factors that go into it," Holland told Mother Jones. "You can't convince me that any one rape was solely because of the temperature."
Still, Ranson's theory is interesting — and, perhaps, could be an additional reason why governments worldwide should begin addressing the issue of climate change more vigorously.