Up to half a million people worldwide die every year as a result of extreme heat, according to a report published by reinsurer Swiss Re on Thursday. +Get the most important news from Switzerland in your inbox That is more than earthquakes, floods and hurricanes combined. Heat stress leads to exhaustion, heat stroke and organ failure or aggravates cardiovascular and respiratory diseases. Elderly people and pregnant women are particularly at risk. And there is evidence that the severity, frequency and duration of extreme heatwaves are increasing.