Extreme heat can be deadly, and as the world warms, the risks to human health are increasing.

Matthews: “History tells us that the impacts of extreme heat are severe, and the projections do paint quite a serious picture of the sort of challenges that may be ahead.”

That’s Tom Matthews of Liverpool John Moores University in the U.K. In a recent study, he found that small increases in global temperatures cause a huge increase in the number of dangerously hot days. These are days when the combined temperature and humidity make it feel like a hundred and five degrees.

Countries across the globe have committed to limiting global warming to 3.6 degrees Fahrenheit.

That will help, but Matthews’ research shows even with warming below that limit, twice as many megacities such as Lagos, Nigeria and Shanghai, China are likely to become heat stressed by mid-century. That could expose more than 350 million additional people to deadly heat.

Matthews: “You’ve got far more frequent hot conditions and you’ve got far more people living in that place to experience those hot conditions.”

So Matthews says the world needs to limit global warming and develop strategies to protect people from the heat.

Reporting credit: Rosie Simon/ChavoBart Digital Media.

Photo: Shanghai, China.