The famous Grinnell Glacier (in Glacier Nation Park, Mont.) has undergone a dramatic recession in recent years. The top photo, taken in 1940, shows the very beginnings of Upper Grinnell Lake in the bottom left corner of the glacier. The bottom photo, from 2004, shows hte expansion of the lake due to the melting of the glacier. As global warming continues, the park is expected to lose all of its namesake glaciers by 2030.