This is the best summary I could come up with:

Life-threatening periods of high heat and humidity will spread rapidly across the world with only a small increase in global temperatures, a study has found, which could cause a sharp acceleration in the number of deaths resulting from the climate crisis.

The study used a limit based on experiments on people showing that when combined heat and humidity, as measured by so-called wet bulb temperature, passes 31.5C, the body is no longer able to cool itself.

The research analysed data from thousands of weather stations across the world to show that 4% had already experienced at least one six-hour period of this extreme heat stress since 1970, with the frequency of such events doubling by 2020.

However, these have been confined to date to hot places, including the Gulf in the Middle East, the Red Sea and the North Indian Plain, where people expect extreme heat.

Dr Colin Raymond, at the University of California, Los Angeles, who was not part of the study team, said: “Many areas are only slightly below the non-compensable heat level now, so as the planet continues to warm, the total increase in exposure will be exponential.

They said there was “a real risk” of widespread exposure with “hundreds of millions of people” affected before they were sufficiently heat-adapted to avoid attendant increases in deaths and illness.

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