Trend in US regions where once-brutal winters are now mild raises new concerns over climate change

This article is more than 1 year old

This article is more than 1 year old

Warmer winters are linked to increased crime rates in parts of the United States, a new study has found.

Researchers found that violent crime is almost always more prevalent when temperatures are warmer in the winter months. The trend was especially strong when winters were mild in regions that usually have fierce winters, like the north-east and midwest.

The study has implications for how America reacts to climate change as the promise of a warming climate could therefore lead to rising crime levels.

'It's a ghost page': EPA site's climate change section may be gone for good Read more

Researchers compared crime and climate data from the FBI’s Uniform Crime Reporting program and the National Oceanic Atmospheric Administration, covering 16,000 cities across the north-east, south-east, south central, west and midwest regions for the study published in GeoHealth.

The crime data covered the years 1979 to 2016.

“The relationship between climate, human interaction and crime that we’ve unveiled is something that will have an impact on people’s wellbeing,” said Ryan Harp, the lead author of the study and a doctoral candidate in the department of atmospheric and oceanic sciences at the University of Colorado Boulder.

The explanation is simple enough: warmer temperatures mean more people are out and about, creating the opportunity for crime.

In technical terms, three elements needed for a crime to occur – a motivated offender, a suitable target and the absence of a guardian such as a police officer – are more likely to come together when the weather is decent.

The link between warmer temperatures and crime all but disappears during the summer months, the study found. That finding cast doubt on an alternative theory, known as the temperature aggression hypothesis, which holds that heat causes stress which makes people more likely to commit crimes.