By the time I arrived, one November a half-century later, the military was gone. The fort had been dismantled and carted off, though two massive, ruined radar domes still sat in the distance like some post-apocalyptic Epcot attraction. A dozen specially built vehicles called Tundra Buggies crawled along the network of dirt roads the military had built and abandoned. Each was stuffed with tourists, many of whom had paid several thousand dollars a head to fly to Churchill, now billing itself as "The Polar Bear Capital of the World." They were mostly older vacationers, taken out to the tundra every day to get a glimpse of the animals, then deposited back in town to prowl the gift shops along Churchill's main road, buying polar-bear caps and snow hats, polar-bear T-shirts, polar-bear aprons, polar-bear Christmas ornaments, polar-bear magnets, polar-bear boxer shorts, polar-bear light-switch plates, polar-bear wind chimes, polar-bear baby bibs, and pajamas that say "Bearly Awake."

A Tundra Buggy, if it resembles anything at all, resembles a double-wide school bus propped up on monster-truck tires. Three had pulled off the road to watch a lone polar bear splayed flat at the rim of a frozen pond, asleep in the willows. I was behind them in a scaled-down vehicle known as Buggy 1, one of the storied, original rigs of the fleet. Buggy 1 is now operated by a conservation group, Polar Bears International. One of the group's videographers was shooting footage of the bear through an open window while the other staff on board tried to sit perfectly still so as not to rattle his tripod. The cameraman had been filming the bear for a long time, in Super HD, hoping it would stand up or do something alluring. Up ahead, tourists filed onto the rear decks of their buggies, training their Telephoto lenses and little point-and-shoots at the animal. It lifted its head once or twice, but that was it. After a couple of minutes, I noticed that the tourists had turned ninety degrees and were photographing us, aboard Buggy 1, instead.

It was then that Martha Stewart's helicopter came into view. Everyone turned to watch it as it passed, flying low and very far ahead. Two hundred years ago, Arctic explorers described polar bears leaping out of the water and into boats, trying to "resolutely seize and devour" whichever dog or human being was sitting closest to their jaws, unprovoked and absolutely undeterred even if you tried to set the bear on fire. Now Martha Stewart had come to Churchill to shoot a special segment about the bears for her daytime television show on the Hallmark Channel.

Polar Bears International had been working in a loose partnership with Martha Stewart for many months in advance to handle logistics for her shoot. The group was trying to ensure that Martha told the right story about the animals. It isn't enough anymore to gush about how magnificent or cute polar bears are, as the many travel writers and television personalities that came to Churchill over the years had tended to. The stakes were too high now--too urgent. Climate change had put the bear in severe jeopardy. According to a 2007 study by U.S. government scientists, two-thirds of the world's polar bears are likely to be gone by the middle of this century. And, of course, that's only one of many dispiriting prognoses trickling into the news these days. Another recent study predicts that climate change may wipe out one of every ten plant and animal species on the planet during that same time. Another claims seven of every ten could be gone. Tropical birds, butterflies, flying squirrels, coral reefs, koalas--the new reality will rip away at all of them, and more. The projections range from bona fide tragedies to more niggling but genuinely disruptive bummers: tens of millions of people in Bangladesh are likely to be displaced by sea-level rise and flooding; the Forest Service warns of maple syrup shortages in America.