Professor Breetzke recently co-authored an article that investigated the link between heat and crime in Khayelitsha, Cape Town. He and his co-authors found that when temperatures exceed 25°C, crime in Khayelitsha increased by 32%. This compares to an earlier study from 2019, where a 1°C increase in temperature translated to a 1.5% increase in murder (see the Open Access article published here). Why would this be? If temperatures increase, people mingle more outside, often consuming more alcohol, explaining the increase in crime. What cannot be easily explained is the 'lag effect' of the current study - that crime often continues (up to a week) at a higher rate after the initial warmer weather.  

And it is not only warmer weather that leads to changes in crime. On cold days (days below 7°C), property crime increased by 50%; an increase of 40% was observed for rainy days. This may be due to climogenic strains (strains or stresses brought on by a changing climate), which are explained by Professor Agnew's general strain theory - that people commit crime because of specific stresses they are exposed to. Climate change thus increases stressors, leading to increasing crime rates. But only where people cannot mitigate the warmer (or colder) temperatures. For example, having access to an air-conditioner to reduce the effects of a hot day outside, will minimise the climate-induced stress and crime rates will not increase because of such factors.

So how can this information be used to manage these effects? If we know that an area will experience hot days, police can ensure they have a greater visible presence, such as conducting more patrols, to prevent potential crime. 

This article is mostly derived from the Daily Maverick article here. The journal article details are given below.

Potgieter, A., Fabris-Rotelli, I.N., Breetzke, G., Wright, C.Y. The association between weather and crime in a township setting in South Africa. International Journal of Biometeorology (2022), DOI: 10.1007/s00484-022-02242-0