Photos: Cities dim for 'Earth Hour'
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SYDNEY, AUSTRALIA - MARCH 31: The sails of the Opera House and the Sydney Harbour Bridge in darkness as the lights are switched off for Earth Hour on March 31, 2012 in Sydney, Australia. Earth Hour encourages individuals around the world to turn off their lights for one hour at 20:30 local time on March 31, 2012 to take a stand against climate change. (Photo by Marianna Massey/Getty Images for WWF Australia)
