Deadly heat coming for healthy people — Harvard research

Venturing outdoors during heatwaves may become deadly for millions of people in a world only slightly warmer than today’s, according to new research that considers the effect of solar radiation, wind, and other factors on the human body.

The study focuses on uncompensable heat, severe enough that even a fit, healthy, hydrated person cannot tolerate it for long. Earlier work largely ignored sunlight and radiation.

The research, published in Communications Earth & Environment, is authored by Yuanchao Fan and Kaighin McColl.

“We incorporated radiative and other effects into a relatively simple model of the human-energy balance and used it to develop future heat stress projections that are considerably more severe than those based on prior approaches.”

In a world 2 degrees Celsius warmer, 24 million farmers would face about eight days of uncompensable heat stress yearly; with 4 degrees of warming, that figure jumps to 127 million.

The hazard also extends into the shade, where models that ignore radiation substantially underestimate risk.

“Climate researchers often rely on heat-stress metrics that focus on weather conditions, while medical researchers study individual responses to heat. Our model bridges this gap.”