[global warming]

Global warming facts:

April 22, 1970:
Millions of Americans observed the first Earth Day.

March 28, 1979:
America's worst commercial nuclear accident occurred inside the Three Mile Island plant near Middletown, Pennsylvania.

April 26, 1986:
The world's worst nuclear accident occurred in Chernobyl, in the Soviet Union.

March 24, 1989:
The supertanker Exxon Valdez ran aground on a reef in Alaska's Prince William Sound and began leaking 11 million gallons of crude oil.

December 3, 1992:
The Greek tanker Aegean Sea spilled 21.5 million gallons of crude oil when it ran aground off northwestern Spain.

March 4, 2002:

The European Union's 15 members ratified the Kyoto Protocol on global warming, but failed to set pollutant-emission levels to meet the accord's targets.

May 14, 2008:
The Interior Department declared the polar bear a threatened species because of the loss of Arctic sea ice.