She’d signed up for the cruise thinking it would be a floating party: Boutiques & Business. You Only Have to Unpack Once! Don’t miss the Polar Ice Cap Break Apart, the brochure said, A Once An Epoch Event! They were far too late to see the really large chunks go, like the ice shelf that collapsed into the Weddell Sea back in 2002, a hunk bigger than Luxembourg. But the ads for this cruise promised the collapse of at least one ice bridge, and the one on today’s stop was massive, spanning a river that had cut through a glacier.

New Age sitar music played. Tourists crowded the ship’s railing, snapping pictures of the ice cliffs. Every time a sheet of ice thundered down into the sea they cheered, the slabs so massive that they seemed to fall in slow-mo, giving up geysers of spray. But it was obvious that everyone was really focused on the main event: seeing the bridge itself collapse. Like a New Year’s Eve crowd waiting for the ball to drop, all heads were turned toward it, whooping louder each time a chunk of ice fell from its underside, thinning the arch. The cheers were motivated, she imagined, by the reasons people always cheered at the watershed between new and old—especially a change of fin de siècle—some cheering for the fresh start it seemed to offer, some cheering for the death of the old, some because they’d simply lived to see it happen, some because it—whatever it was—was really happening, some out of mindless exuberance, some out of fear of the unknown, or worry, or nervousness, or any of the other reasons people also laugh or cry….

When the collapse came, there was no countdown. The massive ice arch failed so suddenly and so completely that it was clear that whatever keystone anyone could imagine had only existed in their imaginations, the arch instead standing the way a house of cards stays upright, one side giving way and pulling down the whole opposing cliff, drowning out the crowd and the sitar soundtrack with its roar—a terrifying, earth-deep rumble—though the cruise ship was far enough away that it only gently rode up, then over, the resulting wave.