Theories propose that temperature is positively associated with homicide rates. Research, however, has found different relationships in locations with distinct climates and socioeconomic conditions. This study explores this heterogeneity using a diverse sample of 108 countries from 1990 to 2018 to test whether rising mean temperatures have contributed to homicide trends. Results describe an association that depends on temperature and development levels. We find a negative quadratic relationship in which predicted homicide rates decline until a mild temperature (18 °C; 64.5 °F) but rise exponentially thereafter. This relationship, however, is moderated by economic development. Wealthier countries, which have the resources to adapt to changing climatic conditions, tend not to experience increased homicide rates as temperatures rise. By contrast, there is a positive temperature-homicide association in poorer and warmer countries concentrated in the Global South. These countries typically have higher baseline homicide rates and fewer resources to mitigate the effects of rising temperatures.
Santos et al. (2025) studied this question.