The World

Does Unusual Weather Cause More Crime?

No rain, no peace.

Photo by Sam Panthanky/AFP/Getty Images

The idea that there’s a relationship between climate change and political instability or warfare is becoming quite a bit more prevalent. But what about crime? Will changing climate and weather patterns have any impact on murders and robberies? One recent study, which focuses on India, is not encouraging.

The working paper, by Lakshmi Iyer of the Harvard Business School and Petia Topalova of the International Monetary Fund, actually sets out to answer an entirely different question—whether there’s a causal relationship between poverty and crime.

Such a relationship might seem obvious, but it’s actually been quite difficult for researchers to pin down in the past. “The idea is very intuitive, but establishing it empirically in a causal way is the hard part,” Iyer tells Slate.

Looking at regional data since the 1980s, the authors found that a “one standard deviation increase in log rainfall is associated with 3.6% lower total crimes per capita. This decrease is primarily driven by decreases in violent interpersonal crimes (4.2% decline), property crimes (2.2% decline) and economic crimes (3.8% decline).”

They then compared the rain data with the income shocks caused by the lifting of India’s trade tariffs during the 1990s, which had a similar impact on crime numbers, indicating that income shocks were the common causal mechanism through both dry weather and economic policy changes that impact crime. In other words, it’s the loss of agricultural productivity and income during dry spells that’s causing people to commit more crimes, not some other endemic factor.

If weather patterns continue to become erratic, it could suggest that governments should expect more crime in response to weather shocks. 

There is a silver lining to the result. “The fact that it’s working through income is actually good news for policymakers, because if you can create policies that compensate for the loss in income, you can avoid a rise in violence crime,” Iyer says. If it were some other factor—for instance, one widely publicized 2001 paper suggested a psychological link between hot weather and violent behavior—governments would have fewer options.

Indeed, as India’s average incomes have increased in recent years, rates of violent crime have decreased. And even with a warming planet, global murder rates have not significantly increased with the exception of a few regions.

Many of climate change’s negative effects may now be unavoidable. But this may be one that it’s possible to prepare for.