Daniel Faegre studies glaciers at Glacier National Park. In 1850, the park contained about 150 glaciers. By 1968, only 37 were big enough to be named on park maps. Aerial photography acquired in 1993 showed that the largest glaciers had shrunk by more than two-thirds, and many of the smaller glaciers were no longer large enough to be called glaciers or had disappeared entirely. Today, there are only 26.

"[The glaciers] are shrinking and may be gone within our lifetimes. Temperatures in Glacier Park have increased by 1.6°C in the 20th century. Several computer models indicate that if current warming trends continue, all the glaciers will be gone between 2030 and 2050."

Grinnell Glacier, 1938

Grinnell Glacier, 1998

Next peice of evidence:
Polar Bears

(1938) Photo by Hileman, courtesy Glacier National Park Archives (1998) Photo by Dan Faegre, courtesy USGS