High temperatures linked to higher homicide rates in Latin American cities

A new study from the SALURBAL-Climate project, published in Environmental Research, examines the link between heat and homicide mortality across 307 cities in seven countries.

• Researchers analyzed daily temperature data and homicide records from 307 cities across seven Latin American countries: Brazil, Chile, Colombia, Costa Rica, El Salvador, Mexico, and Panama.
• Between 2000 and 2019, more than 1.1 million homicides were reported across the 307 cities studied. Of these, 0.61% can be linked to extreme heat exposure.
• High temperatures have been identified as an additional factor within the complex network of factors associated with homicides in Latin America.
• This is the first study to examine the temperature-homicide connection across such a large number of cities in Latin America,  addressing a critical gap as global and regional temperatures continue to rise.

Latin America is currently the most violent region in the world, yet until now, the connection between rising temperatures and homicide deaths has remained largely unexplored. A new study from the SALURBAL-Climate project, published in the journal Environmental Research, provides the first large-scale evidence linking heat and violence across the region.

Led by Sara Lopes de Moraes, PhD, a researcher at the University of São Paulo, the study found that high temperatures are associated with a higher risk of homicide deaths. Over half a percent (0.61%) of all homicides during the study period can be linked to extreme heat.

“Temperature plays a smaller role than structural factors like inequality, weak rule of law, organized crime, poverty, and economic conditions,” said Moraes. “Still, understanding this relationship can help inform strategies to reduce heat-related homicide risk.”

How heat may influence homicide rates

While this study did not directly examine the reasons behind the link, researchers point to two possible explanations. From a biological perspective, the temperature-aggression hypothesis suggests that heat can increase aggressive behavior¹. From a social perspective ^2,3, routine activity theory proposes that hot days bring more people outdoors, where more social interactions—combined with factors like alcohol consumption—can lead to conflict and violence, especially when combined with heat-related irritability and dehydration. Both mechanisms can interact with underlying social factors to trigger homicides.

Policy considerations

As climate change drives up temperatures, addressing the risk of heat-related homicides will become increasingly important. Researchers note that more work is needed to determine the most effective ways to integrate temperature data into routine efforts to prevent violence and homicides. Key strategies to consider include:

• Incorporating heat-related risks into public safety planning and emergency preparedness.
• Developing heat and health action plans that account for the social and behavioral effects of high temperatures.
• Creating heat alert systems to notify law enforcement and support short-term preventive actions in high-risk areas.
• Investing in measures to mitigate high temperatures in cities can be a key strategy that could also help reduce risk factors associated with violence and homicides.
• Strengthen coordination among the health, environment, urban planning, and public safety sectors.

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This study is part of SALURBAL-Climate, a multi-country research partnership generating evidence on the links between climate change and health across Latin America. Contributing institutions include Universidad Nacional de Lanús in Argentina; the University of São Paulo and Federal University of Minas Gerais in Brazil; Universidad Industrial de Santander and Universidad de Los Andes in Colombia; the Instituto Nacional de Salud Pública in Mexico; and the University of California Berkeley, Drexel University’s Urban Health Collaborative, and the University of Michigan School of Public Health in the United States.

This project was funded by the Wellcome Trust (grants 205177/Z/16/Z and 227810/Z/23/Z).

Media Inquires: Carolina Rendón, Communications Specialist, cr3283@drexel.edu

1. Anderson, C. A., Anderson, K. B., Dorr, N., DeNeve, K. M., & Flanagan, M. (2000). Temperature and aggression. In M. P. Zanna (Ed.), Advances in experimental social psychology (Vol. 32, pp. 63-133). Academic Press.
2. Rotton, J., & Cohn, E. G. (2003). Global warming and U.S. crime rates: An application of routine activity theory. Environment and Behavior, 35(6), 802-825.
3. Cohn, E. G. (1990). Weather and crime. The British Journal of Criminology, 30(1), 51-64.