An analysis of mapping police violence data found that police violence in the United States tends to increase slightly when average monthly temperatures exceed 20.3°C (68.5°F). In areas with a population of more than 5 million and rainfall of less than 50 mm, each additional 1°C increase in average monthly temperature above this threshold was associated with an approximately 2% increase in death rates due to police violence. The paper was published in pro swan.
Climate research over the past several decades shows that the Earth is rapidly warming. In 2024, the world’s average surface temperature will exceed 1.5 degrees Celsius above pre-industrial levels for the first time on record. These climate changes are causing increasingly frequent periods of very high daily temperatures.
In humans, exposure to high temperatures, especially temperatures above the comfort level to which the body is adapted, causes physical discomfort, fatigue, and irritability. When people become overheated, they may have difficulty concentrating, making decisions, and controlling their emotional responses. Heat can also disrupt sleep, and sleep deprivation can further worsen mood and self-control. As a result, some studies suggest that very hot climates are associated with higher levels of aggression, conflict, and violence.
High temperatures can increase stress because your body has to work harder to regulate your internal temperature. As a result, people have less patience and are more likely to react impulsively in frustrating situations. Heat can also reduce productivity, especially in jobs that require physical effort or constant attention. Vulnerable groups such as the elderly, children, and people with underlying health conditions may be particularly affected by extreme heat. In extreme cases, exposure to high temperatures can even lead to death.
Study author Jiacheng Zou and colleagues investigated the relationship between high temperature exposure and the risk of police violence in the United States. Although previous research has reported an association between high temperature exposure and violence in general, he noted that few studies have focused specifically on police violence. In this context, police violence refers to incidents in which on-duty or off-duty law enforcement officers use deadly force against civilians, resulting in death, regardless of whether the killing is considered legally justified.
The study authors analyzed data on police violence deaths from the Mapping Police Violence (MPV) website. MPV is one of the most comprehensive databases of victims of police-related fatalities in the continental United States. It consolidates data on deaths caused by police officers using firearms, batons, chokeholds, stun guns, or other methods from 2013 to the present, capturing both incident details and demographic information.
Researchers analyzed 13,381 records in this database detailing incidents that occurred between January 2013 and the end of 2024. The researchers collected weather data for the same period from the climate monitoring database of the National Center for Environmental Information, a division of the National Oceanic and Atmospheric Administration (NOAA). This climate database is a compilation of raw weather observations from multiple stations across the United States. Using this information, the authors calculated the average monthly temperature and precipitation for each U.S. county.
The results showed that police violence became more frequent when the average monthly temperature was above 20.3°C or below -3.2°C. The increase in the frequency of police violence was more pronounced when temperatures rose than when temperatures were very cold.
In areas with a population of more than 5 million people, each additional 1°C increase in average monthly temperature (above the baseline of 20.3°C) was associated with a 2.01% increase in the death rate due to police violence. On the other hand, in areas with monthly rainfall of less than 50 mm, the number of police-related deaths increased by 2.06% for every 1°C increase in temperature. The researchers also noted that the association between high temperatures and the risk of death from police violence became especially pronounced in 2024.
“Our study reveals an association between temperature changes and the risk of police violence and highlights the urgent need for targeted intervention strategies in police law enforcement operations, especially under hot environmental conditions,” the study authors concluded.
This study reveals how human behavior changes under high environmental temperatures. However, it must be noted that police officer behavior is influenced by a complex range of factors that go far beyond environmental conditions, such as the behavior of the civilians involved and the particular escalating developments that lead to violent incidents. Although these fine-grained, individual-level factors could not be fully captured in the study, they are nevertheless still highly relevant for accurately framing and interpreting these results.
The paper, “Rising temperatures are associated with increased risk of police violence: A national county-level study in the United States from 2013 to 2024,” was authored by Jiacheng Zou, Kun Hou, Xia Xu, and Zhen Wang.
