How Increasing Heat from Climate Change Impacts Human Psychology

India and Pakistan experienced a record-breaking heatwave last year, with temperatures soaring above 120 degrees Fahrenheit. The average human body can only withstand “wet bulb” temperatures - a combination of heat and humidity - of about 95 degrees Fahrenheit. As a result, thousands of Indian factories have altered working hours to avoid the midday heat. This minimizes fainting and other incidents when workers operate machinery. Meenu Tewari, an urban planner at the University of North Carolina at Chapel Hill, explains that extreme heat can increase aggression, lower cognitive abilities, and reduce productivity.

Decades ago, psychologist Craig Anderson conducted an experiment where students watched videos of couples engaging in dialogue. Then, they would rate the couples’ mutual hostility level. The students were seated in rooms with 5 different temperatures, ranging from 14 to 36 degrees Celsius. Anderson learned that students in uncomfortably warm rooms would often score couples more hostile. These results suggested that heat causes irritability and could lead to violent behaviors. In recent years, the so-called “heat-aggression hypothesis” has been supported by real-world studies. 

Researchers first examined Los Angeles’ crime data from the years 2010 to 2017. They discovered that the violent crime rate increased by 12 percent on days where temperatures fell between 65 degrees and 70 degrees Fahrenheit. Economists Anita Mukherjee of the University of Wisconsin-Madison and Nicholas Sanders of Cornell University analyzed violence rates in Mississippi prisons without air conditioning. The researchers learned that when the temperature exceeds 27 degrees Celsius, the probability of violence rises by a staggering 18 percent. In total, they estimate that extreme heat generates 4,000 violent acts in U.S. prisons each year. Mukherjee remarks that hundreds of correctional facilities across the nation lack proper climate-control systems and ventilation. As temperatures rise, air conditioning has become an increasing necessity for both prisoner and employee safety. 

Heat is found to negatively influence students’ academic performance across the United States. Economist R. Jisung Park of UCLA gathered 4.5 million standardized exams in New York City from 1999 to 2011. He found that students who took the exam on a 32-degree Celsius day are 10 percent less likely to pass compared to others who took the exam on a 24-degree Celsius day. Park and his colleagues then gathered 21 million PSAT scores from 10 million students across the country from 1998 to 2012. They matched each exam with daily temperature data from 3,000 weather stations and information regarding access to climate-control systems. The researchers found that, on average, students without air conditioning scored significantly lower than others. 

The urban planner Meenu Tewari explored the impact of heat on Indian weaving, garment sewing, and steel industries. She notes that industrial air conditioning is often rare in these factories. After gathering 9 years worth of data, Tewari found that when temperatures exceeded 35 degrees Celsius, the production of garment sewing decreased by 8 percent and weaving decreased by 2 percent. The researchers predicted that, if global temperatures increase by 1 degree Celsius, India’s annual output will decrease by 2.1 percent and the value of goods produced will drop by 3 percent. These predicted economic downturns are similar in other countries with rising temperatures and declining factory conditions.

“The physiological effects of heat may be universal, but the way it manifests … is highly unequal,” says economist R. Jisung Park. Poverty-stricken communities will bear the brunt of extreme heat as they lack access to ventilation and air conditioning. For instance, Park discovered that Black and Hispanic students are more likely to attend school without climate-control systems than White students. These temperature differences likely contribute 3 to 7 percent of the PSAT’s racial achievement gap. Further, the United States’ well-documented discriminatory housing practices mean poor residents live in hotter areas of a city. Climate Science, a research and communication organization, remarked that poor neighborhoods have high density, more paved roads, and less “green space”. This means that less wealthy areas absorb more heat and form “urban heat islands” that can raise temperatures by 8 to 11 degrees Celsius. Further, economist Matthew Kahn of the University of Southern California explains that the poorer communities in Los Angeles have a greater correlation between heat and violent crime.  

As millions suffer from the intense heat, world leaders are searching for ways to cool them down. However, experts agree that more air conditioning is not a sustainable solution. The United Nations reports that 17 percent of the global electricity use is from air conditioning. Most energy used to power air conditioning systems are sourced from oil, coal, and natural gas. Even worse, researchers estimate that air conditioning alone will increase energy consumption 33-fold by 2100. As the global population increases, a cycle will form: greater demand for air conditioning, more nonrenewable resources consumed to power these systems, higher temperatures from global warming, and repeat. 

Tewari and other urban planners are instead promoting more sustainable ways of maintaining comfortable temperatures. They suggest creating more “green space” with parks, trees, and other natural shade. Further, companies can construct buildings with paint and materials that better reflect sunlight. Despite this, poor communities with little investment into infrastructure change will continue to overheat. Instead, countries can attempt to “green” their energy grids with solar panels, turbines, and other technology. This would make air conditioning powered by electricity a viable solution for the world’s growing heat problem.

Works cited:

Gupta, S. (2021, August 25). How extreme heat from climate change distorts human behavior. Science News. Retrieved March 17, 2023, from

https://www.sciencenews.org/article/extreme-heat-climate-change-human-behavior-aggression-equity