Working in high levels of heat and humidity is difficult as it is, but now people working outside are expected to suffer additional productivity loss due to rising global temperatures triggered by global warming.

The productivity loss due to high levels of heat exposure could be as high as $280–311 billion per year, most of which is due to the people engaged in heavy manual labour (agriculture and construction) in low and middle-income countries.

An estimate shows that in the last two decades (2001–2020), an average of 228 billion hours (±27 billion hours/year) of heavy labour have been lost per year due to heat exposure considering a 12hr workday. The losses peaked in 2016 (274 billion hrs/year) and 2019 (270 billion hrs/year).

Qatar and Bahrain are the worst affected countries with more than 300 hrs/person/year labour losses (per capita loss). In terms of cumulative losses, India shows the highest heat exposure impacts on heavy labour (>101 billion hrs lost/year), despite its modest average per-capita labour losses (162 lost hrs/person/year).

An additional 1°C of global warming relative to the present could occur as early as 2037, and another 2°C of warming could occur as early as 2051. This could severely hamper the degree to which the workforce could adapt and will likely impact the productivity and health of the workers.