Climate Change and Human Behavior (Cambridge University Press, 2022) maps out how hotter temperatures and more frequent and severe weather events can directly and indirectly alter the way people think and interact with others.

Leaning on decades of previous research, the authors demonstrate how these impacts at the individual and group levels can escalate to political unrest, civil war, and other forms of violence. They say proactively addressing these challenges now could help buffer some of the long-term costs in the future.

“One of our goals with this book was to outline some of the human costs that are on our doorstep and how core psychological concepts can be used to reduce both the amount of global warming and human violence problems that arise from the climate crisis,” says Iowa State University psychology professor Craig A. Anderson, who wrote the book with Andreas Miles-Novelo, a psychology graduate student.

The authors explain high temperatures cause the brain to divert resources to other parts of the body in an effort to cool down. When this happens, areas of the brain are not running at full capacity, making it harder for someone to process new information, manage emotions, and control impulses. People who are hot also perceive other people as behaving aggressively, which increases the odds of hostile confrontations.

“Heat stress primes people to act more aggressively,” says Anderson. “We can see this play out on a larger scale across geographic regions and over time.”

The authors consistently found that hotter regions in the US and around the world have higher rates of violent crime, even when controlling for other risk factors like poverty and age distribution. Previous research, much of it led by Anderson, also showed a strong connection between hotter stretches of time and violence; murder, rape, and assault rates in the US were higher during hotter days, months, seasons, and years.

The book points to a robust body of developmental research that shows poor pre- and post-natal nutrition is a predictor of being convicted of violent crime as an adult. Stress throughout childhood (e.g., living in poverty or in a violent neighborhood, family separation, economic and housing instability, displacement) also can cause adverse cognitive and emotional outcomes and increase risk factors for violence-prone behaviors.

Read the full article about climate change and violence by Rachel Cramer at Futurity.