Earth Hour At The Colosseum In Rome

(credit: TIZIANA FABI/AFP/Getty Images)

A combo photo shows Colosseum in Rome with lights (up) and without lights (down) during Earth Hour Day, a global event organized by the World Wildlife Fund (WWF), on March 26, 2011. Hundreds of landmark buildings and millions of ordinary homes were switching off their lights as the annual "Earth Hour" moved around the globe in what was dubbed the world's largest voluntary action for the environment.

Earth Hour in Mumbai

(credit: SAJJAD HUSSAIN/AFP/Getty Images)

An Indian child holds lighted candles during an Earth Hour campaign in Mumbai on March 26, 2011. Dozens of Indians lit candles to observe Earth Hour and called for voluntary action against climate change.

Earth Hour in Mumbai

(credit: SAJJAD HUSSAIN/AFP/Getty Images)

Indians hold lighted candles during an Earth Hour campaign in Mumbai on March 26, 2011. Dozens of Indians lit candles to observe Earth Hour and called for voluntary action against climate change.

Earth Hour in Islamabad

(credit: FAROOQ NAEEM/AFP/Getty Images)

Pakistani people gather in front of the parliament house where are displayed candles during an Earth Hour in Islamabad on March 26, 2011.

This combination picture shows the Parth

(credit: LOUISA GOULIAMAKI/AFP/Getty Images)

This combination picture shows the Parthenon (R) and Erechteion Temples at the Athens landmark Acropolis before and after the lights were switched off for Earth Hour on March 26, 2011.

Lights Out At Patronas Twin Towers

(credit: SAEED KHAN/AFP/Getty Images)

This combination of images shows Malaysia's iconic land mark Patronas Twin Towers seconds before (L) and after (R) the lights were switched off for Earth Hour in Kuala Lumpur, on March 26, 2011.

Earth Hour 2011 In China

(credit: ChinaFotoPress/Getty Images)

The Tianyi Square is seen before the Earth Hour 2011 power switch off on March 26, 2011 in Ningbo, Zhejiang Province of China.

Earth Hour 2011 In China

(credit: ChinaFotoPress/Getty Images)

Light's out! About 86 Chinese cities joined a WWF worldwide initiative Earth Hour, to call on people to switch off unnecessary lights for one hour tonight, in support for energy-saving efforts and global warming prevention as a shared responsibility.

Earth Hour 2011 In China

(credit: ChinaFotoPress/Getty Images)

This composite photograph shows "Bird's Nest" before and during the Earth Hour 2011 power switch off on March 26, 2011 in Beijing, China.

Earth Hour 2011 In China

(credit: ChinaFotoPress/Getty Images)

This composite photograph shows Xi'an Bell Tower before and during the Earth Hour 2011 power switch off on March 26, 2011 in Xi'an, Shaanxi Province of China.

Earth Hour 2011 In China

(credit: ChinaFotoPress/Getty Images)

This composite photograph shows Swan Lake before and during the Earth Hour 2011 power switch off on March 26, 2011 in Hefei, Anhui Province of China.

Earth Hour 2011 In China

(credit: Feng Li/Getty Images)

This composite photograph shows the Central Business District before and during the Earth Hour 2011 power switch off on March 26, 2011 in Beijing, China.

Earth Hour In Mumbai

An Indian family hold lighted candles during an Earth Hour campaign in Mumbai on March 26, 2011. Dozens of Indians lit candles to observe Earth Hour and called for voluntary action against climate change.

Light Dim At Seoul N Tower

(credit: PARK JI-HWAN/AFP/Getty Images)

This combo of photos shows the Seoul N Tower before (L) and after (R) the lights were turned off for Earth Hour in Seoul on March 26, 2011.

Taipei Marks Earth Hour

(credit: SAM YEH/AFP/Getty Images)

This combo shows the before and after views of the Taipei 101 building as Taipei marks "Earth Hour" on March 26, 2011.

Sydney Dims For Earth Hour

(credit: Lisa Maree Williams/Getty Images)

In this composite image the Sydney Skyline is seen before (top) and after the lights are switched off for Earth Hour on March 26, 2011 in Sydney, Australia.