Sydney first major city to mark Earth Hour 2009

The floodlit cream shells of the famed Opera House dimmed Saturday as Sydney became the world's first major city to plunge itself into darkness for the second worldwide Earth Hour, a global campaign to highlight the threat of climate change.

From the Great Pyramids to the Acropolis, the London Eye to the Las Vegas strip, nearly 4,000 cities and towns in 88 countries planned to join in the World Wildlife Fund-sponsored event, a time zone-by-time zone plan to dim nonessential lights between 8:30 p.m. and 9:30 p.m.

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. (quote:AP)