Bet Against the Seven Horsemen of the Apocalypse

The Ringwraiths from The Lord of The Rings: The Fellowship of The Ring, 2001. CLICK AHEAD for the seven biggest challenges to sustainability.0xA0Photographer: Warner Bros./Everett Collection

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August 8, 2014 at 10:03 AM UTC

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You know they're out there.

Even people still squeamish about one or another global mega-risk must, deep in their seats of reason, twitch at the thought of these things taking a toll: