Involvement in the effort has exploded since last year's Earth Hour, which drew participation from 400 cities after Sydney held a solo event in 2007. Interest has spiked ahead of planned negotiations on a new global warming treaty in Copenhagen, Denmark, this December. The last global accord, the Kyoto Protocol, is set to expire in 2012.
Despite the boost in interest from the Copenhagen negotiations, organizers initially worried enthusiasm for this year's event would wane with the world's attention focused largely on the global economic crisis, Earth Hour executive director Andy Ridley told The Associated Press. Strangely enough, he said, it's seemed to have the opposite effect.
"Earth Hour has always been a positive campaign; it's always around street parties, not street protests, it's the idea of hope not despair. And I think that's something that's been incredibly important this year because there is so much despair around," he said. "On the other side of it, there's savings in cutting your power usage and being more sustainable and more efficient."
In Australia, people attended candlelit speed-dating events and gathered at outdoor concerts as the hour of darkness rolled through the country. Sydney's glittering harbor was bathed in shadows as lights dimmed on the steel arch of the city's iconic Harbour Bridge and the nearby Opera House.
Earlier Saturday, the Chatham Islands, a group of small islands about 500 miles (800 kilometers) east of New Zealand, officially kicked off Earth Hour by switching off its diesel generators. Soon after, the lights of Auckland's Sky Tower, the tallest man-made structure in New Zealand, blinked off.
Forty-four New Zealand towns and cities participated in the event, and more than 60,000 people showed up for an Earth Hour-themed hot air ballooning festival in the city of Hamilton.
At Scott Base in Antarctica, New Zealand's 26-member winter team resorted to minimum safety lighting and switched off appliances and computers.
China was participating in the campaign for the first time, with Beijing turning off the lights at its Bird's Nest Stadium and Water Cube, the most prominent venues for the Olympics, according to WWF. Shanghai was also cutting lights in all government buildings and other structures on its waterfront, while Hong Kong, Baoding, Changchun, Dalian, Nanjing and Guangzhou were also participating, WWF said.
However, the official WWF Earth Hour Web site appeared to be blocked in Beijing, Shanghai and Tianjin on Saturday afternoon. While China rarely gives reasons for blocking Web sites, the campaign coincided with the 50th anniversary of the suppression of an uprising in Tibet that forced the Dalai Lama to go into exile.
