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Researchers have developed a threshold at which heat waves turn deadly

By 2100, 74% of global population will experience more than 20 days of "deadly heat"

CNN  — 

Deadly heat waves are going to be a much bigger problem in the coming decades, becoming more frequent and occurring over a much greater portion of the planet because of climate change, according to a study published last summer in Nature Climate Change.

Extreme heat waves, such as the several torching the Northern Hemisphere this week are frequently cited as one of the most direct effects of man-made climate change.

The study says, by the year 2100, three out of four people on Earth could be subject to at least 20 days per year of heat and humidity associated with deadly heat waves, if greenhouse emissions continue to rise at their current rates.

Currently, that number is about one in three people.

Even if humans aggressively cut back on fossil fuel emissions, such as outlined in the Paris climate agreement, rising temperatures and humidity levels will combine to increase the intensity and frequency of deadly heat waves, the study said. President Donald Trump recently announced he would be pulling the United States out of the Paris Agreemen