(Agencies)
Updated: 2008-02-19 22:45

SYDNEY - Twenty-four cities around the world will fall into shadow next month as homes and businesses turn off the lights to raise awareness about global warming, organisers said Tuesday.

The Sydney Opera House shines at night as the city turns off its lights to mark "Earth Hour" in 2007. [Agencies]

The "Earth Hour" initiative started in Australia's biggest city Sydney last year when an estimated 2.2 million people flicked the switch -- leaving the Sydney Opera House bathed in moonlight and the Harbour Bridge blacked out.

Organiser Andy Ridley said Sydney's 60-minutes of darkness generated huge interest around the world and 23 other cities from the Asia Pacific, North America, Europe and the Middle East had now signed up to be part of the 2008 event.

The eight latest cities to join "Earth Hour" are Atlanta, San Francisco and Phoenix in the US; Thailand's capital Bangkok; Ottawa, Vancouver and Montreal in Canada and Dublin in Ireland.

They join Australian cities Sydney, Perth, Melbourne, Canberra, Brisbane, Adelaide; Denmark's Copenhagen, Aarhus, Aalborg and Odense; the Philippine capital Manila, Fiji's biggest city Suva, Christchurch in New Zealand; Chicago; Tel Aviv and Toronto.

Ridley said he expected the "Earth Hour" concept, which is managed by the conservation group WWF, to extend beyond the borders of these countries on the scheduled start time of 8:00 pm local time on Saturday March 29.

"I think it already has become much bigger," he said.

"The idea was that anyone could do it, whether they were in a small village in France or a city like Sydney."

Ridley said the Sydney event, in which residents were asked to switch off lights and appliances for one hour, had raised awareness about the problem of global warming while reducing greenhouse gas emissions by conserving energy.

"I know that on the night we thought we might be able to cut energy use in the city by five percent but it ended up being 10.1 percent," he said.

He said he hoped Earth Hour provided a "very big visual message" to politicians that climate change must be addressed quickly.

"The problem is massive but we do make a difference when we all take action," he said.