She also points to this recent science paper that finds a feedback loop. The white fluffy snow that used to cover Greenland reflects sunlight and keeps things cool. When the snow melts, the rock or ice underneath is duller and reflects less light, allowing for greater surface warmth. And more warmth means more snow melt, which means less reflection of sunlight, etc., etc.

via Be Afraid, Very Afraid: Greenland Ice Sheets Cascading into Ocean 50 Years Ahead of Schedule