The effect of last year's Earth Hour was infectious. This year 26 major world cities and more than 300 other cities and towns have signed up to participate.
New Zealand and Fiji kicked off the event this year. In Christchurch, New Zealand, more than 100 businesses and thousands of homes were plunged into darkness, computers and televisions were switched off and dinners delayed for the hour from 8 to 9 p.m. Suva, Fiji, in the same time zone, also turned off its lights.
Auckland's Langham Hotel switched from electric lights to candles as it joined the effort to reduce the use of electricity, which when generated creates greenhouse gases that contribute to global warming.
Australians had their own unique ways to mark the blackout as the clock struck 8 across the nation; one bar was offering free beers to customers who arrived with a black balloon to signify their carbon footprint; staff at beach bar donned solar-powered caps; a bed and breakfast offered candlelight cooking lessons; a children's hospital hosted a pajama party for its patients.
Following Australia, lights will go out in major Asian cities including Manila and Bangkok before moving to Europe and North America as the clock ticks on. One of the last major cities to participate will be San Francisco -- home to the soon-to-be dimmed Golden Gate Bridge.
Organizers see the event as a way to encourage the world to conserve energy. While all lights in participating cities are unlikely to be cut, it is the symbolic darkening of monuments, businesses and individual homes they are most eagerly anticipating.
Even popular search engine Google put its support behind Earth Hour, with a completely black page and the words: "We've turned the lights out. Now it's your turn."
"Earth Hour is a call to action," Sydney's Lord Mayor Clover Moore said at the official launch ceremony. "People have now responded and it's time to introduce some significant long-term changes."
Australians have embraced Earth Hour and other environmental initiatives. The nation of around 21 million people is ranked as the world's worst greenhouse gas emitter per capita, largely because of its heavy reliance on coal-fired power stations. New Prime Minister Kevin Rudd has made the environment one of his priorities, signing the Kyoto Protocol on fighting global warming soon after taking office late last year.