Photos: Cities dim for 'Earth Hour'
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SYDNEY, AUSTRALIA - MARCH 31: Volunteers help light a candle mural on the forecourt of the Opera House representing WWF and 60+ before 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 Mark Metcalfe/Getty Images for WWF Australia)
