Thousands of residents and hundreds of businesses and officials in Australia's biggest city have pledged to switch off their lights for an hour this week to show concern over global warming.

Organizers hope the event will be a dramatic start to a campaign encouraging Australians to conserve energy by turning off lights and other electrical equipment - steps they say could cut Sydney's greenhouse gas emissions by 5 percent a year.

If all goes according to plan, the iconic Sydney Opera House and harbor bridge, along with dozens of skyscrapers and thousands of homes across the city, will go dark at 7:30 pm (0930GMT) on Saturday. Essential lights like aircraft beacons will remain on.

"Earth Hour is an awareness program," wrote Philip McLean, the group executive editor of co-organizer Fairfax Media, in a special section of The Sydney Morning Herald newspaper that invited people to join in.

"It aims to educate the community about the simple measures that can be taken to curb greenhouse gas emissions," he wrote.

The City of Sydney council, New South Wales state government, and businesses big and small have signed on to the event, part-organized by the World Wildlife Fund (WWF). A week ahead of time, more than 30,000 people had registered on a website to take part.

Every weekday, thousands of workers pour out of Sydney's skyscrapers for home, leaving millions of lights and computer screens blazing in empty offices, generating millions of tons of carbon dioxide emissions each year, the WWF says.

If businesses turned off lights, computers, photocopiers and unused appliances, Sydney could cut its greenhouse gas emissions by 5 percent over the next 12 months said WWF's communications director in Australia, Andy Ridley.

Earth Hour is the latest of several environmental initiatives being embraced by Australia, a major consumer of carbon-emitting coal and one of the world's largest per capita producers of greenhouse gas.

Global warming has strengthened into a mainstream political issue, with Prime Minister John Howard's government fighting with the Labor opposition for green credentials while maintaining that the resource-dependent economy must not be harmed by environmental policies.

The government last month announced a plan to phase out incandescent light bulbs and replace them with more energy-efficient fluorescent bulbs.

Source: China Daily/agencies