The end of winter: A search for vanishing snow and ice around the Northern Hemisphere

Greenland is the last leg of a 10,000-mile tour I've taken of the Northern Hemisphere's snow line, documenting how climate change has melted snow and ice.

I've been sitting on the back of a dogsled for three hours now, nestled between a bag of frozen seal blubber, a rifle and three duffel bags as we cruise over the second largest ice mass in the world. Two sleds behind us carry more passengers from Pirhuk Greenland Mountain Guides' annual dogsled expedition into the Arctic Circle. The trip began in the morning, on the outskirts of Kulusuk, a small island on Greenland's remote southeast coast. Discussion then revolved around what had been an unusually warm winter and whether or not the sea ice would be thick enough to sled over. Most of our journey would be on fjords and bays, and if the ice didn't freeze solid we would likely have to turn back.