Above a certain threshold of heat stress, the body’s internal regulation mechanisms are no longer capable of maintaining body temperature at a level required for normal functioning. As a result, there is an increased risk of discomfort, of limitations in physical functions and capabilities, and ultimately also of injuries and heat-related illnesses. The latter illnesses range from mild forms, such as heat rash, heat cramps and heat exhaustion, to potentially fatal heatstroke. If the body temperature rises above 38°C (“heat exhaustion”), physical and cognitive functions are impaired; if it rises above 40.6°C (“heatstroke”), the risk of organ damage, loss of consciousness and, ultimately, death increases sharply (IPCC, 2014a).
Global costs are expected to continue to rise with estimates of as much as $2.4 trillion in lost productivity due to heat-induced decreases in worker capacity by 2030.
By 2030 the equivalent of more than 2 per cent of total working hours worldwide is projected to be lost every year, either because it is too hot to work or because workers have to work at a slower pace.
Heat stress is increasingly becoming an obstacle to economic activity. It reduces the ability of businesses to operate during the hottest hours. Adapting to these new and threatening conditions is costly.
Even if it does prove possible to limit global warming by the end of the century to 1.5°C above preindustrial levels, the accumulated financial loss due to heat stress is expected to reach US$2,400 billion by 2030. If nothing is done now to mitigate climate change, these costs will be much higher as global temperatures increase even further towards the end of the century.