PHOTOS: When the world switched off lights for an hour

A combination picture shows the India Gate before (bottom) and during the earth hour in New Delhi.

Earth hour, when everyone around the world is asked to turn off lights for an hour from 8.30 pm local time, is meant as a show of support for tougher action to confront climate change.

Photographer: Mansi Thapliyal/Reuters

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The Chicago skyline is seen before (top) and during earth hour in Chicago, Illinois, in this combination picture made March 23, 2013.

Photographer: Jim Young

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A combination picture shows the Chinese National Stadium, also known as the ''Bird's Nest', is seen reflected before (top) and during the earth hour at the Olympic Park in Beijing.

Photographer: Stringer/Reuters

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A combination photo shows the Marina Bay Sands hotel and the Art Science Museum (right), before (top) and during earth hour in Singapore.

Photographer: Natashia Lee/Reuters

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A combination picture shows a general view of the Parliament building and the Sukhbaatar statue before (top) and during the earth hour at Sukhbaatar Square in Ulan Bator.

Photographer: B Rentsendorj/Reuters

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The Angel Independence Monument is seen before (top) and during (bottom) earth hour in Mexico City, in this combination picture.

Photographer: Henry Romero/Reuters

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A combination photograph shows the skyline with the Empire State Building on the right before (top) and during (bottom) earth hour in New York.

Photographer: Carlo Allegri/Reuters

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Earth hour is observed at Berlin's Brandenburg Gate, the Cologne Cathedral and in Frankfurt's city centre (left to right) during (top) and before the lights were switched off

Photographer: Lisi Niesner/Reuters

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A combination picture shows the Sydney Opera House on March 21, 2013 (top) before and during earth hour.

Photographer: Daniel Munoz/Reuters

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A combination picture shows the entrance to the Sydney amusement park 'Luna Park' on March 21, 2013 (top) before and during earth hour.

Photographer: David Gray/Reuters

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Leifeng Pagoda is seen behind the West Lake before (left) and during the earth hour in Hangzhou, Zhejiang province

Photographer: Chance Chan/Reuters

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