KEY POINTS

  • Past researches found a correlation between global warming and violent crimes
  • Warmer winters have increased violent crime rates
  • In a new study, researchers looked at the effects of future global warming on crime rates
  • The U.S. may see 20,000 to 50,000 additional violent crimes each year in a warming planet

Previous studies have correlated seasonal climate and regional violent crime rates in the continental United States. In a continuously warming planet, how will future climate change affect violent crime rates?

Winter Crimes

When researchers Ryan Harp and Kristopher Karnauskas scoured historical climate data from the NOAA as well as crime data directly from the FBI in 2018, they found that warming winters, in particular, are correlated to jumps in violent crimes such as burglary, murder, larceny, and motor vehicle theft. This is possibly because the calmer weather allowed for more interaction between people.

“During mild winters, more people are out and about, creating the key ingredient for interpersonal crimes: opportunity,” Harp had said when the study came out.

In the past, there were marked declines in such “outdoor” crimes during cold winters, but warmer temperatures appear to be changing the trend. In fact, in certain regions in the United States, the relationship was so tight during the winter that the temperature change alone could explain half of the year by year changes in crime rates. By summertime, the relationship disappeared.

Future Violent Crime Rates

For a new study published in Environmental Research Letters, the team combined empirical models from previous studies with 42 state-of-the-art global climate models to see how future effects of climate change may affect violent crime rates until 2099.

Interestingly, the researchers found that the continental U.S. may expect an additional 2 to 3 million more violent crimes between 2020 to 2099. That means that each year, we could see about 20,000 to 50,000 additional violent crimes. The range, researchers say, strongly depends on how much and how fast the Earth warms.

While there are many factors that can influence violent crime rate in the U.S., the study shows how climate change has quickly become a significant one. In fact, the researchers note that such overlooked social impacts of climate change could cost the nation $5 billion per year.

“We are just beginning to scratch the surface on the myriad ways climate change is impacting people, especially through social systems and health,” Karnauskas said. “We could see a future where results like this impact planning and resource allocation among health, law enforcement, and criminal justice communities."