CNN reports:

As triple-digit heat tests the limits of California’s electrical grid to keep millions of people cool, it is clear the effects of human-caused global warming are already here.

But the extreme heat baking the Western US is a mere preview of what could be coming: A new study finds that in the future, the heat risk facing the country’s biggest cities could be far greater than previously thought.

Without cuts to greenhouse gas emissions, major US cities could see roughly between 13 and 30 times more population-adjusted exposure to extreme heat by 2100 as compared to the beginning of this century, the study found.

The study was published Monday in the journal Proceedings of the National Academy of Sciences, and adds to the abundant evidence that mankind’s ability to halt global warming and adapt to rising temperatures will be two of the defining challenges of this century. [Continue reading…]