Warmer Climates May Contribute to Higher Violence Rates

Sunset over city on hot dayHot climates may produce more aggressive behavior, according to a paper published in the journal Behavioral and Brain Sciences. Drawing upon several previous studies, the study’s authors—led by Paul A. M. Van Lange of Vrije Universiteit in Amsterdam—say climate can change culture, which may alter aggression levels.

Are Southern Regions Less Peaceful?

According to the Federal Bureau of Investigation (FBI), the American South is more violent than other regions of the United States. In 2012, 40.9% of all violent crime occurred in the South, even though only a quarter of the U.S. population resides there.

Northern countries are disproportionately represented in the Global Peace Index (GPI), which relies on indicators of violence. In 2014, the GPI listed Iceland, Denmark, Austria, New Zealand, Switzerland, Finland, Canada, Japan, Belgium, and Norway as the most peaceful countries. Southern nations dominated the list of least peaceful countries. In 2014, Russia, North Korea, Pakistan, the Democratic Republic of the Congo, Central African Republic, Sudan, Somalia, Iraq, South Sudan, Afghanistan, and Syria were listed as the least peaceful nations.

Do Warm Climates Make People Aggressive?

The study notes that, with some exceptions, violence tends to increase with proximity to the equator. Previous researchers have posited several theories. For example, the Routine Activity Theory suggests people spend more time socializing in warm climates, allowing more opportunities for aggression to occur.

The new study suggests an alternative model, called Climate, Aggression, and Self-control in Humans (CLASH). This model suggests lower temperatures and wider variation in seasons force people to focus more on the future, cultivating self-control so they can save resources for times of inclement weather and deprivation.

People who live in warmer climates, by contrast, may be more focused on the present. The researchers say this so-called “fast life” strategy can lead to aggression due to a decrease in self-control and increase in impulsive behavior. Other factors, such as the unpredictability of venomous animals and the infectious diseases that tend to proliferate in warm climates, can intensify this tendency toward aggression.

A 2013 meta-analysis of aggression and geography looked at 60 studies on the correlation. The researchers found a clear association between warmer climates and more aggression with a 14% increase in conflict for each standard deviation in climate.


  1. Baer, D. (2016, July 7). Do hot climates make people more violent? Retrieved from http://www.cnn.com/2016/07/07/health/climate-violence/index.html
  2. Global Peace Index 2014 [PDF]. (2014). New York: Institutes for Economics and Peace.
  3. Hsiang, S. M., Burke, M., & Miguel, E. (2013). Quantifying the influence of climate on human conflict. Science, 341(6151). doi:10.1126/science.1235367
  4. Lange, P. A., Rinderu, M. I., & Bushman, B. J. (2016). Aggression and violence around the world: A model of CLimate, Aggression, and Self-control in Humans (CLASH). Behavioral and Brain Sciences, 1-63. doi:10.1017/s0140525x16000406
  5. Violent crime up, property crime down. (2013, September 16). Retrieved from https://www.fbi.gov/news/stories/2013/september/latest-crime-stats-released/latest-crime-stats-released

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  • Leave a Comment
  • Bery

    July 13th, 2016 at 10:53 AM

    I am not saying that this is not right, but how then do you explain the violence in some of the Mid Atlantic states with our largest cities?
    They are certainly not near the equator

  • Lois

    July 13th, 2016 at 2:41 PM

    There is something about being all hot and sweaty that sometimes leads to hotter tempers I guess for lack of a better descriptor. Maybe it is just more uncomfortable so everyone tends to take out their aggression on other people? Who knows. factor in the heavier drinking that goes on in the summer and for some that could be the recipe for an anger incident.

  • bennett

    July 14th, 2016 at 2:16 PM

    have never heard this theory before, but ok, I will go with it

  • Samuel

    July 15th, 2016 at 7:19 AM

    And I have read a few stories lately about the high rate of suicide in climates that are colder, so maybe there is something that is relevant there about how the weather effects you in different ways.

  • Clara

    July 15th, 2016 at 10:01 AM

    I live in an urban area and yes, when the temps go up outside I think that there are definitely more of us on edge, just not as nice in general to one another as we probably are when it feels a little more comfortable outside.

  • Jon

    July 18th, 2016 at 11:34 AM

    very interesting study- can certainly feel that tempers flare a little more easily in the summer months

  • alec

    July 19th, 2016 at 2:14 PM

    Just more of that vast left wing conspiracy trying to convince us that global warming is a real thing ;)

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