Chicago plans to join more than 20 other cities and shut off exterior lights on public buildings for an hour in an effort to raise environmental awareness.

The voluntary hour of energy conservation is to occur worldwide on March 29 from 8 p.m. to 9 p.m. as part of Earth Hour 2008, sponsored by the World Wildlife Fund, the Chicago Tribune reported Saturday.

It's "a symbolic gesture to remind us that we all share the responsibility of global warming," Chicago Mayor Richard Daley said Friday.

Exterior lights also will turn off for the hour on Chicago landmarks such as the Merchandise Mart, Sears Tower and the John Hancock Center, said a World Wildlife Fund statement.

Other participating cities include Toronto, Manila, Bangkok, Copenhagen, Melbourne and Tel Aviv.

Copyright 2008 by United Press International

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