Earth Hour 2012: Before and After

Chillon Castle During Earth Hour

Photograph by Jean-Christophe Bott, Keystone/AP

Chillon Castle sits dark during Earth Hour, which always occurs in late March.

Earth Hour is timed to occur during the spring and autumn equinoxes in the Northern and Southern Hemispheres, respectively.

That means that sunsets will occur at roughly the same time around the globe—"thereby ensuring the greatest visual impact for a global 'lights out' event," according to the Earth Hour website. (See Earth Hour pictures from 2011.)

Published March 22, 2013

Tianjin Eye Ferris Wheel Before Earth Hour

Photograph by Wang Qingyan, Imaginechina/AP

The Tianjin Eye Ferris Wheel glimmers before Earth Hour in Tianjin, China.

A total of 124 Chinese cities joined urban centers around the world in turning off the lights of their landmark buildings in 2012.

Published March 22, 2013

Tianjin Eye Ferris Wheel During Earth Hour

Photograph by Wang Qingyan, Imaginechina/AP

The Tianjin Eye Ferris wheel is seen after the lights were turned off to mark Earth Hour in Tianjin, China.

That year, Earth Hour launched I Will If You Will, a platform to incentivize and inspire individuals to share their commitment to the planet with others, according to the Earth Hour website.

Published March 22, 2013

Great Wall of China Before Earth Hour

Photograph by Vincent Thian, AP

The Great Wall of China is lit up shortly before the lights go off to mark Earth Hour.

In a WWF survey conducted after Earth Hour 2009, 80 million U.S. citizens said they had participated, WWF spokesperson Leslie Aun said in 2010. (Read more about Earth Hour 2010.)

"Cities and businesses are the ones you're always hearing about, because they have the skyscrapers and the big marquees. But Earth Hour has always been an event about families and individuals as well," Aun said.

Published March 22, 2013

Great Wall of China During Earth Hour

Photograph by Vincent Thian, AP

The Great Wall of China darkens during Earth Hour. Those participating in Earth Hour should only turn off the non-essential lights for one hour—not lights that affect public safety, according to organizers.

Published March 22, 2013

Prambanan Temple Before Earth Hour

Photograph by Gembong Nusantara, AP

Lights illuminate the 9th-century Hindu temple of Prambanan in Java, Indonesia.

In 2012, Earth Hour created the Earth Hour City Challenge, which rewards pioneering cities that are "leading the way towards a fully sustainable future," according to the website. More than 70 percent of the of the world's carbon dioxide emissions—a major greenhouse gas—is generated by cities.

Published March 22, 2013

Prambanan Temple During Earth Hour

Photograph by Gembong Nusantara, AP

The Hindu temple of Prambanan sits dark during Earth Hour.

On the eve of the 2013 Earth Hour, UN Secretary General Ban Ki-moon said in a statement, "We participate with an undimmed determination to take action on climate change. Everyone has a role to play.

"Governments need to provide the political will, businesses can contribute solutions, and civil society, especially young people, can mobilize global action."

Published March 22, 2013

See Pictures of Earth Hour 2011

Photograph by Felipe Dana, AP

Published March 22, 2013