Children march while holding candles during Earth Hour in Lima March 31, 2012. Lights started going off around the world on Saturday in a show of support for renewable energy. The banner reads, "Turn off your lights". REUTERS/Enrique Castro-Mendivil (PERU - Tags: ENVIRONMENT SOCIETY)
Chilean volunteers hold up candles during Earth Hour in Valparaiso city, about 121 km (75 miles) northwest of Santiago, March 31, 2012. Lights started going off around the world on Saturday in a show of support for renewable energy. REUTERS/Eliseo Fernandez (CHILE-Tags: - Tags: ENVIRONMENT SOCIETY TPX IMAGES OF THE DAY)
The Brooklyn Bridge is seen before the lights are turned off, in participation with Earth Hour, in New York March 31, 2012. Lights started going off around the world on Saturday in a show of support for renewable energy. REUTERS/Allison Joyce (UNITED STATES - Tags: ENVIRONMENT SOCIETY CITYSPACE)