I am a scientist who researches climate hazards. This week I have published research on the potential for a catastrophic cyclone-heatwave combo in the global south.
The headline-grabbing 46°C recently experienced by Britain's neighbours in France is indeed unusual, but still falls short of the 50°C recorded in India earlier this summer, and is somewhat temperate relative to the 54°C (129°F) confirmed for both Pakistan (in 2017) and Kuwait (in 2016). People in these hotter climates are better at coping with high temperatures, yet such heat still kills.
Deadly heatwaves are, of course, no stranger to Europeans. The infamous 2003 event claimed as many as 70,000 lives, and 2010 saw more than 50,000 fatalities in western Russia. Fortunately, lessons were learned and authorities are now much better prepared when heat-health alerts are issued.
When the air temperature exceeds 35°C, the body relies on the evaporation of water – mainly through sweating – to keep core temperature at a safe level. This system works until the "wetbulb" temperature reaches 35°C. The wetbulb temperature includes the cooling effect of water evaporating from the thermometer, and so is normally much lower than the normal ("drybulb") temperature reported in weather forecasts.
