Population exposure to heat is increasing due to climate change, and this trend will continue. Globally, extreme temperature events are observed to be increasing in their frequency, duration, and magnitude. Between 2000 and 2016, the number of people exposed to heat waves increased by around 125 million. In 2015 alone, 175 million additional people were exposed to heat waves compared to average years. Single events can last weeks, occur consecutively, and result in significant excess mortality. In 2003, 70 000 people in Europe died as a result of the June-August event, in 2010, 56 000 excess deaths occurred during a 44-day heatwave in the Russian Federation. Exposure to excessive heat has wide ranging physiological impacts for all humans, often amplifying existing conditions and resulting in premature death and disability. Who is affected? Rising global ambient temperatures affect all populations. However, some populations are more exposed to, or more physiologically or socio-economic