How dangerous is extreme heat to humans?

The media reporting around heat waves that have hammered the northern hemisphere has been unequivocal: the simultaneous record-breaking heat has "pushed the limits of human survival."

Tropical forests nearing critical temperatures thresholds

Global warming is driving leafy tropical canopies close to temperatures where they can no longer transform sunlight and CO2 into energy, threatening total collapse if the thermometer keeps climbing, according to a study Thursday.

July was the planet's hottest month on record—so far

A sizzling month marked by record heat waves, major wildfires, melting sea ice and a burgeoning El Niño will go down in the books as the hottest July on record—at least until next year, federal officials said Monday.

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