High temperatures are linked to slightly increased rates of police violence

An analysis of Mapping Police Violence data found that police violence in the U.S. tended to be slightly higher when average monthly temperatures exceeded 20.3°C (68.5°F). In areas with over 5 million people and in areas with less than 50mm of precipitation, each additional 1°C increase in the monthly average temperature above this threshold was associated with a roughly 2% increase in the rate of deaths caused by police violence. The paper was published in PLOS ONE.

Climate studies over the past few decades have indicated that our planet is rapidly warming. In 2024, global average surface temperatures exceeded 1.5°C above pre-industrial levels for the first time on record. These climate shifts have resulted in increasingly frequent periods of very hot daily temperatures.

In humans, exposure to high air temperatures—specifically temperatures above comfortable levels to which the body is adapted—produces physical discomfort, fatigue, and irritability. When people are overheated, they may find it harder to concentrate, make decisions, or control emotional reactions. Heat can also disturb sleep, and poor sleep can further worsen mood and self-control. Consequently, several studies suggest that very hot weather is associated with higher levels of aggression, conflict, and violence.

High temperatures may increase stress because the body has to work harder to regulate its internal temperature. As a result, people may become less patient and more likely to react impulsively in frustrating situations. Heat can also reduce productivity, especially in jobs that require physical effort or sustained attention. Vulnerable groups, such as older adults, children, and people with underlying health conditions, may be especially affected by extreme heat. In extreme cases, exposure to high air temperatures can even lead to death.

Study author Jiacheng Zou and his colleagues investigated the relationship between heat exposure and the risk of police violence in the U.S. They noted that while previous studies have reported links between exposure to high temperatures and general violence, few have focused specifically on police violence. In this context, police violence refers to incidents in which an on-duty or off-duty law enforcement officer uses lethal force against a civilian, resulting in death, regardless of whether the killing is legally considered justified.

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The study authors analyzed data about deaths caused by police violence from the Mapping Police Violence (MPV) website. The MPV is one of the most comprehensive databases of victims of police-related fatalities in the continental United States. It integrates 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.

The researchers analyzed 13,381 records from this database detailing incidents that occurred between January 2013 and the end of 2024. They collected meteorological data for that same period from the climate monitoring database of the National Centers for Environmental Information, a division of the National Oceanic and Atmospheric Administration (NOAA). This climate database compiles raw meteorological observation data from multiple monitoring stations across the U.S. Using this information, the authors calculated the monthly average temperatures and precipitation for each U.S. county.

The results showed that police violence becomes more frequent when average monthly temperatures exceed 20.3°C or fall below −3.2°C. The increase in the frequency of police violence was more pronounced at increasingly higher temperatures than it was under very low temperatures.

In areas with over 5 million people, each additional 1°C increase in the monthly average temperature (above the 20.3°C threshold) was associated with a 2.01% increase in the rate of deaths caused by police violence. Meanwhile, in areas with less than 50mm of monthly precipitation, each additional 1°C rise in temperature was associated with a 2.06% increase in police-related deaths. The researchers also noted that the association between high temperatures and the risk of death caused by police violence was particularly notable in the year 2024.

“Our research reveals the linkage between temperature variation and the risk of police violence, highlighting the urgent need for targeted intervention strategies in the practices of police law enforcement, particularly under the high-temperature environmental conditions,” the study authors concluded.

The study sheds light on how human behavior changes under high environmental temperatures. However, it should be noted that the behavior of police officers is influenced by a complex range of factors that go well beyond environmental conditions, including the behavior of the civilians involved and the specific, escalating developments that lead to a violent event. These granular, individual-level factors could not be fully captured in the study, yet they remain highly relevant for the accurate framing and interpretation of these findings.

The paper, “Higher temperatures are associated with increased risk of police violence: A nationwide county-level study in the United States, 2013–2024,” was authored by Jiacheng Zou, Kun Hou, Xia Xu, and Zhen Wang.