Suspiciously close timing to the recent wave of Mt. Everest (and other) mountain climbing... and the associated human waste added to the snow. This leads to a change in the albedo, and thus, to greater heat retention. I blame Tenzing Norgay for helping that English dude climb Everest. If it wasn't for those meddling sherpas, the mountains would have gotten away (with keeping the cloaks of snow).
