I spent the summers of 2007 and 2008 on a glacier in southeast Alaska, with 12 people and 200 huskies. I was working as a dogsled guide, and each morning I'd pull myself from my sleeping bag, slip on my raincoat and boots, and step from my tent into the pale light of the Northern summer, the glacier luminous beneath me in the rising sun. Eight times a day, a distant purr would echo over the mountains, and a line of helicopters grew in the sky until they were right above us, whipping our hair and filling our ears with the sound of engines. I waited by my sled as the passengers disembarked, then led them on a tour, skimming across the ice field in gentle silence before returning to the waiting choppers and preparing for the next run. At night, when the last round of helicopters had disappeared,