The helicopter took off from Ilulissat airport and headed west, up and over the coastal ridge to the ice cap that covers Greenland. The airstrip is so close to the coast that icebergs float only a few hundred feet from the runway. We flew about 60 miles inland. Although I had flown over the ice cap for hours, I wanted to step outside and feel the impact of climate change on my feet. When I stepped outside, my foot sank in the slush. The entire ice cap is melting. Instead of solid snow and ice, rivers and lakes are in a process of continuous transformation to fresh water. I didn't feel curiosity or excitement. I felt a sense of dread and instability. Like most glaciers in the world, on the southwest coast of Greenland the glaciers are thinning at the edge of the ocean. As they retreat, the calving fronts where icebergs are made may also disappear. Right now, scientists say that these vast rivers of water on top of the glacier are finding their way down into the ice cap and creating huge rivers beneath flowing to the sea; convection routes for fresh water that will eventually contribute to rapid sea level rise. The greatest story in the history of the world is unfolding in our time, and at least one political party in the United States denies it is even happening.