How hot is too hot for humans?

As my fellow Floridians know, the only way to survive a humid summer day is to find air conditioning, fast. Humidity makes us uncomfortable because we sweat in order to cool off, but this cooling is less efficient when it’s humid. Past a certain threshold of heat and humidity, our bodies can no longer cool off by sweating, and the results can be lethal. A recent study by Coffel et al. suggests that, by the end of the century, climate change may expose millions of people to life-threatening heat stress.

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Are we headed for a sixth mass extinction?

A mass extinction is an event in which the world very rapidly loses a large number of its living species. You’ve probably heard of the mass extinction that occurred sixty-five million years ago, when an asteroid crashed near Mexico and led to the extinction of the dinosaurs. There have been four other mass extinctions in the last 500 million years, and each has resulted in the loss of at least 60% of living species. In a recent study, Professor Daniel Rothman at the Massachusetts Institute of Technology argues that human activities – specifically our inundating the atmosphere with carbon – may result in a sixth mass extinction.

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