Climate change and crime

Research suggests a complex relationship between climate change and crime. As global temperatures rise, some studies indicate an increase in crime rates, especially violent crimes.^[1] However, the evidence is mixed, with some studies finding only weak or inconsistent correlations. Factors such as temperature volatility,^[2] seasonal variations,^[3] and geographical context^[1] play a role in influencing crime rates. Additionally, environmental crimes, such as illegal waste dumping and unauthorized emissions, can contribute to climate change, creating additional factors that may influence crime patterns.^[4]

Criminologists and researchers have proposed various theories to explain the potential relationship between rising temperatures and crime rates. These theories explore different mechanisms through which temperature might influence crime.

The temperature-aggression theory, also known as the biological theory, suggests that higher temperatures can lead to increased levels of stress and irritability in individuals, potentially resulting in more aggressive behaviors.^[5] According to this theory, as temperatures rise, people may become more prone to frustration and anger, which could contribute to an increase in violent crimes such as assaults and homicides.^[4][5] Several studies have explored this concept, examining whether heat-induced aggression correlates with higher rates of violent crime.^[2][4] One approach to temperature aggression theory involves examining historical data to identify correlations between heat waves or abnormally high temperatures and increased rates of violent crimes.^[2] Researchers look for patterns in crime data across different seasons or during specific weather events to determine whether there is a significant increase in violent crime rates during hotter periods.^[2] In doing so, researchers also consider various variables, such as time of day, location, and demographics, to control for external influences and to gain a clearer understanding of the temperature-aggression link.^[2][6]

The routine activity theory states that crime is more likely to occur when three conditions are met: a motivated offender, a suitable target, and a lack of capable guardianship.^[7] Warmer weather often leads to more outdoor activities and social interactions, creating more opportunities for motivated offenders to find suitable targets where there is little or no guardianship.^[1][8] This theory suggests that during warmer periods, with more people engaging in outdoor activities, there may be an increased likelihood of criminal activities such as theft and burglary.^[1][9] The routine activity theory does not imply that higher temperatures directly cause crime, but it emphasizes that environmental factors, such as weather, can affect human behavior and create conditions conducive to criminal activity.

Geographic locations, urban or rural environments, and community infrastructure can all influence how routine activity theory applies to crime rates.^[8][7] In urban settings, the increased density of people during warmer weather can create more chances for criminal behavior.^[9] In contrast, rural areas might have different patterns due to variations in social interactions and community structures.^[2][9]

Numerous studies have examined the relationship between temperature and crime, yielding varied results:

• A study investigating the "climate change-temperature-crime hypothesis" across 15 U.S. cities over a 14-year period found that most correlations between temperature and crime were insignificant, which the researchers said suggested that other social, economic, or environmental factors might be more influential.^[1]
• One study looked at the impact of temperature and precipitation on crime in St. Louis, Missouri from 1990 to 2009.^[6] The study concluded that increased temperature anomalies lead to an increase in monthly crime rates. In particular, it found a positive correlation between violent crimes, like aggravated assaults, higher temperatures, and a shorter rainy season.^[6] They concluded this relationship was mild but they found a strong positive relationship between the temperature anomalies during El Nino/La Nina cycles and civil conflict.^[6]
• Another study examined annual temperatures and crime rates in the U.S., finding a positive correlation with certain crime types, such as assault and robbery, while other types, like murder, showed no significant relationship.^[10]
• A study by Trujillo and Howley from 2021 in Barranquilla, Colombia, found that higher temperatures significantly increased interpersonal violence, while higher humidity and precipitation were linked to decreased violence.^[11] The study supported the general aggression model and concluded that weather factors were important in urban security policies.^[11]

One study investigated the effects of rainfall fluctuations on dowry-related deaths in India.^[12] The researchers concluded that a one standard deviation decrease in annual rainfall from the local mean is associated with a 7.8% increase in reported dowry deaths.^[12] Wet shocks, or periods of excessive rainfall, reportedly have no significant impact on dowry deaths.^[12] Additionally, the study found a deficit in rainfall is associated with a 32% increase in domestic violence incidents.^[12] They state in their report that this may indicate a possible connection between economic stress due to poor agricultural yields during droughts and higher crime rates, particularly domestic abuse and dowry-related violence.^[12] While dry periods are correlated with increased domestic violence and kidnapping/abduction cases in the study, they do not significantly affect burglary and robbery rates.^[12]

Climate change is said to increase strain by exposing individuals to a range of stressors or stressful conditions conducive to crime.^[13] These strains include extreme weather events, food and freshwater shortages, habitat changes, and forced migration.^[13] These conditions can lead to negative emotions such as anger, frustration, and fear, creating pressure for corrective action, with crime being one possible response.^[13] Robert Agnew’s theoretical model suggests that climate change will likely become a significant driver of crime due to its multifaceted effects on society, including increased strain, reduced social control, weakened social support, and increased opportunities for crime.^[13]

Another perspective on resource scarcity and crime involves the potential of climate change litigation to mitigate conflicts and atrocity crimes.^[14] A law study done by Yvonne Breitwieser-Faria at The University of Queensland stated that successful litigation can address environmental and economic stresses that exacerbate these issues. It concluded that such litigation may help alleviate the conditions that lead to increased crime rates by advancing climate policies and reducing environmental degradation.^[14]

Environmental crimes, such as illegal waste dumping, deforestation, and unauthorized emissions of pollutants, contribute to climate change by accelerating global warming.^[15] This environmental degradation can indirectly lead to an increase in violent crime rates.^[4] Nicolette Pellegrino, an environmental law professor, suggests that rising temperatures and natural disasters— consequences of climate change—are associated with a higher incidence of violent crimes.^[4] She states that this connection could be due to several factors. Natural disasters can lead to increased social disruption, economic instability, and resource scarcity, all of which may contribute to heightened stress and conflict within communities, potentially leading to a rise in violent crime.^[4] The resulting environmental degradation might push vulnerable communities toward poverty and instability, potentially contributing to conditions that foster violent crime.^[4]

To address the link between environmental crimes and climate change, some strategies have been proposed. These include advocacy and education to raise public awareness about the impact of climate change on violent crime rates.^[4] Organizations like Greenpeace and initiatives such as Earth Day work to promote sustainability and educate people about climate change.^[4] Increasing sanctions for regulated or criminal activities contributing to climate change and holding individuals accountable for environmental wrongdoing are among the suggested solutions.^[4] The study by The University of Queensland mentioned above notes that legal actions can advance climate policy, reduce environmental degradation, and lower the risk factors associated with violent crimes.^[14]

Geographic variations can play a role in the relationship between climate change and crime, as different regions may exhibit unique crime patterns.^[10][16] Factors such as climate, urbanization, and socioeconomic conditions can influence how weather-related changes affect crime rates.^[16]

A study focusing on North Bay, Ontario, a smaller urban area with a population of about 50,000, examined the impact of weather variables on crime rates in a smaller urban area.^[16] The study found that temperature influenced the distribution of thefts, while assaults were positively correlated with temperature.^[16] Break and enters were more influenced by calendar events, and domestic disputes were more frequent on weekends.^[16] This highlights the importance of considering all sizes of urban areas and suburban areas when studying the relationship between weather and crime.

Socioeconomic conditions can play a role in crime patterns and how communities are effected by climate change.^[16] Regions with higher poverty rates or greater economic instability may experience more crime, which could also be exacerbated by climate change's impact on local economies since people in poverty are often more affected by climate change due to limited resources, reduced access to essential services, and greater vulnerability to extreme weather events, which can exacerbate these existing socioeconomic inequalities.^[16][17] Additionally, climate change can lead to resource scarcity, disrupted agricultural practices, and increased migration, all of which can contribute to heightened social tensions and crime.^[4]

Seasonal variations also influence crime patterns.^[3] Changes in weather and temperature across seasons can lead to shifts in social behavior, which may influence the occurrence and types of crime.^[3] As climate change causes more extreme weather fluctuations within the seasons, crime rates are also exhibiting greater variations.^[3]

Warmer weather is often associated with more people spending time outdoors, engaging in recreational activities, attending events, or simply socializing in public spaces.^[2] This increased social activity can lead to a rise in crime rates due to the greater potential for interactions between motivated offenders and suitable targets.^[2][3]

A study in Cleveland, Ohio, examined the impact of maximum daily temperature on outdoor violent crime, finding a strong positive correlation between high temperatures and violent crimes occurring outdoors.^[2] This study supported and proposed the routine activity theory as an explanation, suggesting that as temperatures rise, there is a greater chance for criminal behavior due to increased outdoor activity and interactions.^[2]

Seasonal variations with climate change can also manifest as sudden temperature anomalies, where temperatures deviate significantly from the seasonal norm.^[3] A study that explored sudden temperature anomalies in 28 U.S. cities from 2015 to 2021 found that upward temperature swings correlated with increased robbery and homicide, especially during winter months.^[8] The researchers conducting this study suggested that unexpected warmer weather during typically colder seasons can lead to a spike in violent crimes.^[8][3]

Different seasons are associated with unique crime patterns.^[3] During summer months, when temperatures are typically higher, outdoor activities increase, potentially leading to more crime.^[2][3] Crimes like theft, robbery, and assault tend to rise during warmer periods, possibly due to the increased opportunities for crime as more people are outside and engaging in social activities.^[10][2][3]

Conversely, colder seasons can lead to a reduction in outdoor activities, which might result in lower crime rates for certain types of crimes.^[3] However, as noted in the study of 28 U.S. cities, sudden upward temperature anomalies during winter can disrupt this trend, leading to a rise in violent crime rates.^[8]

A study published in the International Journal of Offender Therapy and Comparative Criminology used a retrospective approach to examine the seasonal fluctuations of property crime in two Canadian cities, Vancouver, British Columbia, and Ottawa, Ontario.^[18] The study found that cities with greater weather variations, such as Ottawa, experience more pronounced increases in property offenses during the summer months.^[18] In contrast, Vancouver, which has a relatively mild and consistent climate, was reported to have less distinct seasonal variations in property crime.^[18]

The impact of seasonal variations on crime can also vary depending on the type of crime.^[9] Property crimes, such as burglary and theft, might increase during warmer seasons when people are more likely to leave their homes unattended.^[3] On the other hand, violent crimes like assault and homicide could see an uptick due to increased social interactions and the potential for confrontations.^[2][8]

One study disaggregated property crime into specific types to examine how weather and temporal variables uniquely impact different offenses.^[18] In Vancouver, warmer temperatures and rainfall were associated with increased theft from vehicles.^[18] In Ottawa, higher temperatures and longer daylight hours were linked to increases in commercial and residential break and enters, but not with robbery or theft of vehicles.^[18]