A look at how the environment initative was recognized
People hold candles as they gather outside the Galileo Galilei planetarium to observe Earth Hour in Buenos Aires, March 29.
Students and visitors hold torches as they observe Earth Hour outside Fleming College's Frost Campus for Environmental Studies in Lindsay, Ont.
Candles placed by participants to create the number 60, representing the minutes in an hour, marking Earth Hour in La Paz, Bolivia.
People hold candles as they watch a performance during Earth Hour in Sao Paulo.
Saudis gather in a park during celebrations to mark the worldwide Earth Hour in Riyadh, Saudi Arabia.
The "Puente Nuevo" (New Bridge) is seen during Earth Hour in Ronda, near Malaga, Spain.
The UNESCO World Heritage Cologne Cathedral and the Hohenzollern railway bridge along the river Rhine are seen during Earth Hour.
The Old Bridge is pictured during Earth Hour in Mostar.
The lights are turned off at the Kremlin during the worldwide Earth Hour in Moscow.
Times Square is pictured during Earth Hour in New York.