Warmer Winters May Mean To More Violent Crime, Says CU Boulder Study

Nov 23, 2018

As global temperatures continue to rise, parts of the U.S. may see an uptick in violent crime rates. A new study from the University of Colorado Boulder indicates a rise in crimes such as assault, robbery, rape and larceny during warmer winters. Data from more than 16,000 cities across the U.S. was compared with climate date over regions, as opposed to just states.

Similar studies on violent crime rates have been done before, by economists, criminologists, and psychologists, but not climatologists. Ryan Harp, lead author of the study and a Ph.D. candidate at the University of Colorado and the Cooperative Institute for Research in Environmental Sciences, says what makes their research unique is a zoomed-out comparison of weather and crime data from regions around the U.S.

“Milder, more pleasant weather leads to more people leaving their homes, going out and about,” Harp said, “and you’re increasing the chances that a perpetrator and a victim will cross paths without a guardian present.”

Harp’s conclusion is based on the routine activities theory. It says that crime is driven by a combination of three ingredients; a motivated offender, a suitable target, and the absence of a guardian who could prevent a violation. So pleasant weather may increase the chances of all three factors converging; lousy weather may decrease it.

The study was led by CIRES, is a partnership between CU Boulder and the National Oceanic and Atmospheric Administration.

The study was published in the journal GeoHealth.