Alpine habitat near the Denali Park entrance has retreated up the mountains in places more than 200 feet in the last 20 years from increased shrubby willow. Loss of habitat from slumping permafrost has also affected sheep habitat.  There are square miles of once fine, firm alpine tundra that is now muddy, slumping, unwalkable mess.  I am talking about glacier cirques frozen since the end of the ice age.  No sign of this happening steadily over the last hundred years either.  It is something new.  Caribou are also greatly affected, as evidenced by their new trails they create to skirt the lands they once roamed widely. There is indisputable evidence of the habitat loss all over up here. Those that express doubts are simply willfully blind to it, or speaking out of self interest (or tribal politics).