The Great Wall before Earth Hour. ©REUTERS/Jason Lee
The Great Wall during Earth Hour. ©REUTERS/Jason Lee
Hong Kong's central financial district during Earth Hour. ©REUTERS/Siu Chiu
Palacio de los Capitanes during Earth Hour in the Central Place of Antigua, Guatemala. ©REUTERS/Jorge Lopez
People light candles during Earth Hour after lights were turned off in Cali, Colombia. ©REUTERS/Jaime Saldarriaga
Children light a candle while marching during Earth Hour in Lima, Peru. ©REUTERS/Enrique Castro-Mendivil
Combo picture shows Sydney Harbour Bridge and city skyline before and during Earth Hour. ©REUTERS/TIM WIMBORNE
Chilean volunteers hold up candles during Earth Hour in Valparaiso city. ©REUTERS/Eliseo Fernandez
Fire acrobats perform in front of Ivan Vazov national theatre during Earth Hour in Sofia, Bulgaria. ©REUTERS/Stoyan Nenov
The Empire State Building is seen with its lights turned off in participation of Earth Hour in New York, the U.S. ©REUTERS/Allison Joyce
An ice-cream cart is pictured next to the India Gate during Earth Hour in New Delhi, India. ©REUTERS/Parivartan Sharma
People hold candles during Earth Hour after lights were turned off in central Amman, Jordan. ©REUTERS/Ali Jarekji
Students hold candles as they attend Earth Hour in front of the monument Baiterek in Kazakhstan's capital Astana. ©REUTERS
A combination shows the 97-metre monument Baiterek before and during Earth Hour in Kazakhstan's capital Astana. ©REUTERS
Philippine police hold candles as they join the celebration of Earth Hour in Manila's Makati financial district. ©REUTERS/Cheryl Ravelo
A man poses with an iPhone during Earth Hour in the center of Brasilia, Brazil. ©REUTERS/Ueslei Marcelino