People use candles to create the number 60, representing the minutes in an hour, as they mark Earth Hour in La Paz, Bolivia, Saturday March 31, 2012. Earth Hour takes place worldwide at 8:30 p.m. local time and is a global call to turn off lights for 60 minutes, as a symbolic act to raise awareness about climate change and to make people aware of everyday energy use.
Few lights remain switched on for an hour in the financial district of Makati city, east of Manila, Philippines as households observe Earth Hour Saturday March 31, 2012. The Earth Hour is observed in thousands of cities across the globe on every last Saturday of March as part of a global effort to shine a spotlight on climate change.
A child lights a candle during a ceremony to mark Earth Hour at Palace Square in St.Petersburg, Russia, Saturday, March 31, 2012. Earth Hour takes place worldwide at 8.30 p.m. local times and is a global call to turn off lights for 60 minutes in a bid to highlight the global climate change.
Combo of images show before, left, and after pictures of St Stephen's Tower in London Saturday March 31, 2012, during Earth Hour. Earth Hour takes place worldwide at 8.30 p.m. local time and is a global call to turn off lights for 60 minutes in a bid to highlight the global climate change.
Volunteers of the World Wide Fund For Nature (WWF) place candles amongst about 5000 candles to picture the globe prior to 'Earth Hour' in front of the Brandenburg Gate in Berlin, Saturday, March 31, 2012. Earth Hour takes place worldwide at 8.30 p.m. local time and is a global call to turn off lights for 60 minutes in a bid to highlight the global climate change.
The Great Wall of China went dark as the landmark switched off the lights to mark 'Earth Hour' as part of a global effort to shine a spotlight on climate change in north of Beijing, China, Saturday, March 31, 2012.