This combo of pictures shows Buenos Aires' Planetarium with the lights on (top) and with the lights off (bottom) during the sixth annual Earth Hour on March 31, 2012. Millions of people were expected to switch off their lights for Earth Hour on March 31 in a global effort to raise awareness about climate change that was even to be monitored from space. AFP PHOTO / Alejandro PAGNI
This combo of pictures shows Buenos Aires' Piramide de Mayo with the lights on (L) and with the lights off (R) during the annual Earth Hour event on March 31, 2012. Millions of people were expected to switch off their lights for Earth Hour on March 31 in a global effort to raise awareness about climate change that was even to be monitored from space. AFP PHOTO / Alejandro PAGNI
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)