Environmental Impacts:

• The 20th century's last two decades were the hottest in 400 years and possibly the warmest for several millennia.
   

• 2007 tied the record for being the hottest year.
   

• Montana’s Glacier National Park now has 27 glaciers, versus 150 in 1910.
   

• In the Northern Hemisphere, thaws come a week earlier in spring and freezes begin a week later.
   

• Ice now covers 15 percent less of the Arctic Ocean than it did 20 years ago.