Beware the Heat Wave

A heat wave signals more than hot temperatures.  It means a surge in violent crime.

Rising temperatures increase the rates of homicides, sexual offences and assaults. Riots and uprisings also tend to take place during summer.  This is borne out by research conducted in a number of countries.  Twitter online hate speech also increases during hot weather, according to a recent study on climate impacts.

There are a couple of theories about this.  One is that hot temperatures make us uncomfortable, frustrated and therefore more aggressive.  Academic research points to a heat-related change in our serotonin levels as a possible explanation.  Testosterone also rises in hot weather, which offers a theory for the increase in sexual violence.  There may also be a connection in impaired cognition and mood.

People celebrating beach party

But all this doesn’t explain why violent crime rises in areas that are normally cold and where an increase in temperature doesn’t necessarily become uncomfortable. (ie Finland)

A second theory kicks in:  Warmer days lead to altered routines and activities.  People tend to party, gather and increase social contacts, leading to settings where there is more likelihood of conflict.  Inhibitions melt away.

Frustrated driver in traffic jam on hot day

Other factors apply.  For instance, a study of U.S. cities found a strong correlation between temperature and homicides especially in areas where there are socioeconomic inequalities.

The seasonality of crime has been suspected for centuries, and known for almost 200 years.   In 1831 Adolphe Quetelet, a Belgian statistician and social scientist showed there’s a seasonal pattern to different types of crime.  His discoveries led to criminology as a science.

Keep Calm and Read a Book

The outlook is that as climate change makes summers hotter and heat waves more common, we’ll be dealing with a rising tide of violent crimes.

I feel a story coming on….

Further reading: