Australia's Sydney Harbour Bridge and Opera House were plunged into darkness on Saturday for the annual Earth Hour campaign, leading a global effort to raise awareness on climate change.
In a twist to this year's Earth Hour, Dutch astronaut Andre Kuipers will observe from the International Space Station countries around the world turning off the lights for 60 minutes from 8.30 p.m. local time and post photos.
From Sydney's sparkling harbour to Egypt's Tahrir Square and New York's Empire State Building, thousands went dark when the switches were flicked in some 150 countries and territories.
The Pacific island nation of Samoa was the first to make the symbolic gesture, with New Zealand's city landscapes later dramatically darkened as lights on buildings such as Auckland's Sky Tower were cut.
In Australia, where the event was conceived, harbourside buildings went dark, along with most big office buildings as some Sydneysiders picnicked on the harbour foreshore by moonlight.
Japan's Tokyo Tower interrupted its sunset-to-midnight lighting to take part, as organisers said the Earth Hour was an opportunity to pray for last year's earthquake and tsunami disaster.
In Hong Kong, the city's skyscrapers turned out their lights dimming the usually glittering skyline. Tourists and locals snapped pictures, although many were unaware of what was behind the switch-off.
Since it began in Sydney in 2007, Earth Hour has grown to become what environmental group WWF says is the world's largest demonstration of support for action on carbon pollution.
A total of 5,251 cities took part in 2011, as the movement reached 1.8 billion people in 135 countries, it says. Newcomers to the worldwide initiative include Libya and Iraq.
“Earth Hour 2012 is a celebration of people's power — the world's largest mass environmental event in support of the planet,” said chief executive of WWF-Australia Dermot O'Gorman.
“And we're seeing hundreds of millions of people in different countries around the world take actions to go beyond the hour in support of positive actions for climate change and the planet.”
In Beijing, Olympic Park's two landmark monuments, the Bird's Nest and Water Cube, were spending an hour in darkness.
And in Singapore, 32 malls — many located in the glittering Orchard Road shopping belt — and more than 370 companies including luxury brands such as Louis Vuitton and Armani turned off non-essential lighting.
In Taiwan, the presidential office went dim and in the Philippines, more than 1,780 police stations and training centres turned off all non-essential lights and electrical equipment.
In the Indian capital New Delhi, lights at India Gate, Qutub Minar and Humayun's Tomb were switched off.
