Leifeng Pagoda, behind the West Lake before (left) and with its lights off (right), during Earth Hour in Hangzhou, Zhejiang province, China, on March 23, 2013. Earth Hour, an hour when everyone around the world is asked to turn off lights from 8.30 p.m. local time, is organized by the World Wide Fund for Nature (WWF), and is meant as a show of support for tougher action to confront climate change. #

A before-after pair of images showing the Empire State building in New York City, lit up and (click to fade) with lights off during Earth Hour. [click image to view transition - javascript required] #

The Bosphorus Bridge that links Istanbul's European and Asian sides, with the European side in the background, before, and during (click to fade) Earth Hour in Istanbul, Turkey, on March 23, 2013. [click image to view transition - javascript required] #

The monument "Mother Motherland" before, and during (click to fade) Earth Hour in Kiev, Ukraine, on March 23, 2013. [click image to view transition - javascript required] #

The lighted Welcome Monument located in central Indonesia's capital city of Jakarta with lights on, and (click to fade) during Earth Hour, on March 23, 2013. [click image to view transition - javascript required] #

The Bank of China Tower, Cheung Kong Centre, The HSBC Building and Standard Charter building, before, and during (click to fade) Earth Hour, on March 23, 2013 in Hong Kong. [click image to view transition - javascript required] #

Vienna's city hall in the evening of March 21, 2013, and during Earth Hour (click to fade) in Austria, on March 23, 2013. [click image to view transition - javascript required] #

The National Library of Belarus before, and (click to fade) after the lights are turned off during Earth Hour in Minsk, on March 23, 2013. [click image to view transition - javascript required] #

The Eiffel Tower, before and after submerging into darkness (click to fade) at 8:30 pm, as part of the Earth Hour switch-off on March 23, 2013 in Paris. [click image to view transition - javascript required] #

The UNESCO World Heritage Cologne Cathedral and the Hohenzollern railway bridge along the river Rhine, before, and during (click to fade) Earth Hour, on March 23, 2013. [click image to view transition - javascript required] #

Buildings illuminate the Hong Kong skyline minutes before and during (click to fade) the annual Earth Hour event where a reported 3,800 buildings and landmarks switched off their lights, on March 23, 2013. [click image to view transition - javascript required] #

A combination picture shows the financial Central District of Hong Kong before, and during (click to fade) Earth Hour, on March 23, 2013. [click image to view transition - javascript required] #

The Chinese National Stadium, also known as the "Bird's Nest", reflected before, and during (click to fade) Earth Hour, at the Olympic Park in Beijing, on March 23, 2013. [click image to view transition - javascript required] #

The ancient Temple of Parthenon atop the Acropolis, before and (click to fade) during Earth Hour in Athens, Greece, on March 23, 2013. [click image to view transition - javascript required] #

The Marina Bay Sands hotel and the ArtScience Museum, before, and during (click to fade) Earth Hour in Singapore, on March 23, 2013. [click image to view transition - javascript required] #

St. Basil's Cathedral, Red Square and the Kremlin before, and (click to fade) during Earth Hour in Moscow, on March 23, 2013. [click image to view transition - javascript required] #

Yintai Center (left) and China World Trade Center Tower III (right) before and during (click to fade) Earth Hour, in Beijing's central business district, on March 23, 2013. [click image to view transition - javascript required] #

The monument "As Bandeiras" before, and during (click to fade) Earth Hour, in Sao Paulo, Brazil, on March 23, 2013. [click image to view transition - javascript required] #

Wat Arun Ratchawaram in Bangkok, Thailand, before, and during (click to fade) Earth Hour, 2013. [click image to view transition - javascript required] #

The downtown Singapore skyline, before and during Earth Hour (click to fade), on March 23, 2013. [click image to view transition - javascript required] #

Lions Gate Bridge before, and during (click to fade) Earth Hour, in Vancouver, British Columbia, on March 23, 2013. The World Wildlife Fund crowned Vancouver the title of Global Earth Hour Capital for 2013. [click image to view transition - javascript required] #

Brandenburg Gate, before and during (click to fade) Earth Hour in Berlin, on March 23, 2013. [click image to view transition - javascript required] #

The city skyline of Frankfurt, Germany, on the banks of Main river before Earth Hour and during (click to fade), on March 23, 2013. [click image to view transition - javascript required] #

The Bund on the banks of the Huangpu River before, and during Earth Hour (click to fade), in Shanghai, on March 23, 2013. [click image to view transition - javascript required] #