Five minutes past midnight in Svalbard: The wild world is awake and clattering. At the edge of a sheltered estuary in the Adventdalen, a valley on a cluster of islands halfway between Norway and the North Pole, a flock of arctic terns soar and wheel in the perpetual daylight. They're agitated. A pair of glaucous gulls—chick snatchers, egg stealers, the Arctic's formidable winged predators—are approaching from the east. The terns put up a fierce defense. They flash their red beaks at the gulls and turn themselves into a cloud of sharpness.
The gambit works. The gulls bypass the terns and circle inland, passing over a pair of ground-nesting eiders, a kennel of sled dogs, and a solitary reindeer feeding on the tundra.
It's a typical summer night in Svalbard, an entirely atypical refuge in the high Arctic that abounds with an extraordinary array of wildlife. Few places in the circumpolar region can match its biodensity. Polar bears thrive here. Roughly half the estimated 3,000 bears in the Barents Sea population raise their young on the archipelago's isolated islands, and humans are warned not to venture beyond town without a rifle as protection against Ursus maritimus. Seabirds migrate to Svalbard in the millions. Five species of seals and 12 kinds of whales feed in the waters off its coast. Atlantic walruses prosper on the rich clam beds along the shallow shelf of the Barents Sea. On the open tundra of Svalbard's plateaus and valleys, reindeer forage and arctic fox hunt free from predators.
To the human eye, the terrain is stark, austere, unforgiving. More than half the landmass is encased in glacial ice. Less than 10 percent offers enough light and soil to support vegetation. On a summer climb up the rocky slopes of Nordenskiöldfjellet (Mount Nordenskiöld), I counted only seven different plant species in five hours—and those clung to a tenuous existence, hunkering between sheltering plates of broken rock like hermits in a desert.
Years ago when Norwegian archaeologist Povl Simonsen considered the limits of human survival in the far north, he spoke of the "edge of the possible." For most of its history, Svalbard has existed beyond that edge. Ancient civilization never got a toehold here. The Vikings didn't colonize it. The Inuit stayed away. Even today, as tourists enjoy daily air service from Oslo, just 2,500 people live here year-round, many working in Svalbard's coal mines. Winter brings perpetual darkness.
But for a select number of species, Svalbard acts as an extraordinary cradle of life. And the secret to the place isn't bound up in the land. Svalbard is ruled by water, light, and temperature.
Up here the biotic machine is fueled by the Gulf Stream, which sweeps up the East Coast of the United States. If you rode the Gulf Stream's main branch, the North Atlantic Current, all the way north, you'd end up in the West Spitsbergen Current off the coast of Svalbard. There the warm, salty current (though at 42°F, "warm" is a relative term) keeps the water mostly ice free and nurtures massive plankton blooms every spring. The plankton lure whales and great schools of capelin and polar cod, which provide food for seabirds and seals. The abundance of seals, in turn, keeps Svalbard's polar bears fed. Adult bears consume a huge amount of seal blubber, primarily from ringed seals and bearded seals. That food produces the energy necessary to keep the bears' massive bodies (males commonly weigh up to 1,300 pounds, females about half that) moving over a home range that can vary from 60 square miles up to 144,000.
The energy-rich waters off the coast also draw an annual infusion of seabirds. Every May and June, when the ice retreats and the tundra clears of snow, upwards of three million birds flock to Svalbard. They're vast in number but not variety. Only about 28 species are considered common or abundant, and only one—the Svalbard rock ptarmigan—has what it takes to survive on land year-round. The birds migrate up here for the safe breeding and the nonstop feasting. A quirk of geology makes the whole thing work. In places, Svalbar