THE HELICOPTER LANDED on top of the cliff, its blades chopping the cold air. Stepping out, Gina Moseley breathed deeply and took in the commanding view of Greenland’s barren landscape. To the south, a frozen lake stretched out for miles, eventually giving way to brown and gray plateaus, interrupted by the white flash of glaciers in the distance. In the other direction, some 560 miles beyond the horizon, was the North Pole. The only other human presence was the helicopter pilot and the other passengers: Moseley’s life partner and this story’s photographer, Robbie Shone, and technical climbing spe-cialist Chris Blakeley. The weather was mild, just above freezing—perfect, actually—but Moseley knew that storms could blow up at a moment’s notice, bringing dangerous winds and dense fog. In such a case, they’d have…