Sydney's iconic Harbour Bridge and Opera House temporarily went dark today as nations across the western Pacific turned out the lights for Earth Hour 2010 to call for action on climate change.
The symbolic one-hour switch-off, first held in Sydney in 2007, has become an annual global event and organisers World Wide Fund for Nature (WWF) said they expect this year's to be the biggest so far.
The remote Chatham Islands was the first of more than 100 nations and territories to turn off the power at 8.30 pm local time, in a rolling event around the globe that ends just across the International Dateline in Samoa 24 hours later.
Event co-founder Andy Ridley said that 126 countries and territories had so far signed up, with thousands of special events scheduled, including a lights-out party on Sydney's northern beaches and an Earth Hour 'speed dating' contest.
From a boat on Sydney harbour, one witness said the city was already in darkness hours before the event, low clouds and a near full-moon adding an eery feeling to the nation's largest city.
In the Chatham Islands, diesel generators that supply power locally were switched off. Other early participants included New Zealand, Fiji and Tuvalu, where driving was halted temporarily.
The number of participants is significantly up on 2009, when 88 countries and territories and more than 4,000 towns and cities took part. Organisers have estimated between 500 million and 700 million people were involved last year.
Mr Ridley said he believed the perceived failure of last year's Copenhagen conference on climate change had stimulated interest this time.
"There is real frustration with the politics around climate change," Ridley, WWF's executive director of Earth Hour, he said.
Business had shown strong support, he said, including the world's major hotel chains, which he said are responsible for a significant chunk of global emissions.
Organisers say they do not actively monitor the amount of energy saved as it is insignificant in terms of what the world needs, and the event is purely symbolic anyway.
"What it does, I hope it gives you an hour to think about what you can do and what can be done," Mr Ridley said.
World icons taking part for the first time this year include the presidential Blue House in South Korea and the Forbidden City in Beijing.
In Hiroshima, Japan, the city's peace memorial will go dark, as will the pyramids and the Sphinx in Egypt.
Here in Ireland, Leinster House, Government Buildings and the Four Courts are among the buildings which will be plunged into darkness.
All the bridges over the Seine in Paris are also going to have their lights turned off as will the Eiffel Tower and the Arc de Triomphe. So will the London Eye, Buckingham Palace and London's Tower Bridge. In the United States, more than 30 of the 50 state governors have lent their support.
Some, though, criticised the event.
"To hold a candles-and-champagne party indoors, on the mildest night of the year, for just one hour, shows that the whole thing is green tokenism. Moreover, both candles and champagne emit carbon dioxide," said Viv Forbes, chairman of climate change sceptic group the Carbon Sense Coalition.
Reuters