How extreme heat from climate change distorts human behavior

Nearly ten years ago, Meenu Tewari was visiting a weaving company in Surat, western India, on a hot summer’s afternoon. Tewari is an urban planner who visits manufacturing enterprises often to gain insight into their operations. But she was perplexed after her factory floor visit that day.

The University of North Carolina at Chapel Hill’s Tewari claims that “there were no workers there… only machines.”

The missing workers weren’t far away; they were napping under a nearby awning for shade. Tewari’s guide informed her that the intense heat had been causing workers to trip or even pass out in close proximity to the hazardous apparatus. In order to provide employees with time to relax during the noon heat, the corporation had implemented an earlier start and later finish schedule.

Human beings aren’t designed to withstand heat above wet bulb temperatures, which are approximately 35° Celsius or 95° Fahrenheit. Wet bulb temperatures are a combination of heat and humidity. A growing body of research indicates that when people’s bodies are taxed by heat, it affects not only how well they perform on different tasks but also how well they cope in general. Extreme heat has been associated by researchers with increased hostility, decreased cognitive function, and, as Tewari and colleagues demonstrated, decreased productivity.

A few decades ago, for example, social psychologist Craig Anderson and colleagues played four film recordings of couples having conversations to undergraduate students. Three of the clips showed the couple’s tension building, while one had a neutral tone. The undergraduate students viewed the clips while seated in separate rooms with thermostats set to a range of five degrees, from a cool 14°C to a scorching 36°C. Next, the researchers had the students rate how hostile the couples were to each other. Current Iowa State University in Ames researcher Anderson discovered that students in uncomfortable heated rooms rated every couple—including the neutral one—as more antagonistic than those in pleasant circumstances. Remarkably, kids in extremely cold rooms also received high scores.