Heat stress linked to climate change means that workers, particularly those with outdoor jobs, work and earn less. One-fifth of worker output could be lost.

When temperatures topped 35 degrees Celsius (95 F) for a few days in Europe last week, collective complaints of heat exhaustion could be heard loudly among outdoor and office workers alike.

But, across equatorial nations in sub-Saharan Africa and southern Asia, rising temperatures are forcing people to work amid severe heat stress for much of the year.

Global heating and declining productivity

Low-income workers employed in agriculture or construction who primarily work outdoors are especially vulnerable to heat stress. The overt health consequences are heat exhaustion, heat stroke and sometimes death. But researchers are increasingly tracking the link between heat stress and declining productivity as part of the economic case for climate action.

In South Africa, per capita GDP will decline up to 20% by 2100 because of heat stress if warming occurs at the top-line prediction of 3.5 degrees Celsius (6.3 degrees Fahrenheit), according to a 2020 study co-authored by researchers at the Venice-based Euro-Mediterranean Center on Climate Change (CMCC).