A Hard Day’s Work

Increased heat stress brought on by global warming could drastically cut the amount of work people can safely perform during the hottest months, according to a study in Nature Climate Change.

As the Earth warms up, humidity also increases, the authors say. Such changes “pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress,” they write. People can tolerate temperatures higher than 35 degrees Celsius, but prolonged work in such sweltering conditions can be dangerous.

The researchers calculated how changes in wet-bulb globe temperature — a heat stress indicator that takes humidity into account — would affect humans’ ability to work. If carbon dioxide levels keep rising over the next two centuries, labor capacity during the hottest parts of the year will fall to 63 percent in 2100 and 39 percent in 2200, the team estimates. Cities such as New York and Washington, DC could face conditions “well exceeding heat stress levels of present-day Bahrain,” the authors write.

The team acknowledges that many factors remain unknown, such as the amount of future coal extraction. The study also doesn’t account for the possibility that warmer weather could increase labor capacity in some cases by extending growing seasons for farmers and lowering the number of cold, snowy days. Roberta Kwok | 25 February 2013

Source: Dunne, J.P., R.J. Stouffer, and J.G. John. 2013. Reductions in labour capacity from heat stress under climate warming. Nature Climate Change doi: 10.1038/nclimate1827.

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