Why some heatwaves prove deadlier than others


After the 2003 disaster, many European countries created heatwave action plans and began issuing early warnings. Experts say preparing for extreme heat can save lives.

“More people know what to do in response to a heatwave,” said Chloe Brimicombe, a heatwave researcher at the University of Reading in Britain. But some countries are simply better equipped than others: almost 90 per cent of European households, according to US federal statistics.

But technology can’t always help. This year, Palestinians living on the crowded Gaza Strip are living through a searing summer heatwave that has been made worse by power cuts that leave them without electricity for as much as 10 hours a day.

Nearly a third of the US population was under a heat warning last month, with forecasts predicting more extreme heat this month.

People living in poorer communities and the homeless are at higher risk.

During last year’s heatwave in Phoenix, Arizona, 130 of the 339 people who died were homeless, local health officials said.

Some US cities, including Phoenix, have hired ‘heat officers’ to help communities cope by handing out water bottles or guiding people to air-conditioned cooling centres.

“The risk of heat-associated death among our unsheltered neighbours is 200 to 300 times higher than the rest of the population,” Phoenix heat officer David Hondula said.


People who live in warm-weather countries have typically acclimated to high heat. As a person is repeatedly exposed to high temperatures, they develop a lower heart rate and core body temperature over time, improving their tolerance.

So the temperature at which people start to die from heat-related illness varies depending on location, as does the related “Minimum Mortality Temperature (MMT)” when all deaths from natural causes reach their lowest point.

“If you’re living in India, the MMT is much higher than if you’re in the UK,” Huber said.

Recent research also suggests that the MMT of an area can increase as heat rises. For every 1 degree Celsius rise in average summertime temperatures in Spain between 1978 and 2017, for example, scientists found a 0.73 degrees Celsius increase in MMT, a study published in April in Environmental Research Letters journal said.

But with much still unknown about extreme heat and human endurance, scientists are not sure if the changes they are seeing in MMTs over time might also be related to people being more aware of the dangers, or better equipped to deal with them.

“There are several possible explanations, and we still don’t know which is the most important cause,” Huber said.