A combination picture shows the Sydney skyline before (top) and after the lights were turned off for Earth Hour March 28, 2009. [Agencies]

Lights went out at tourism landmarks and homes across the globe on Saturday for Earth Hour 2009, a global event designed to highlight the threat from climate change.

From the Sydney Opera House and Harbour Bridge to the Eiffel Tower in Paris and London's Houses of Parliament, lights were dimmed as part of a campaign to encourage people to cut energy use and curb greenhouse gas emissions from fossil fuels.

Organizers said the action showed millions of people wanted governments to work out a strong new U.N. deal to fight global warming by the end of 2009, even though the global economic crisis has raised worries about the costs.

"We have been dreaming of a new climate deal for a long time," Kim Carstensen, head of a global climate initiative at the conservation group WWF, said in a candle-lit bar in the German city of Bonn, which hosts U.N. climate talks between March 29 and April 8.

"Now we're no longer so alone with our dream. We're sharing it with all these people switching off their lights," he said.

The UN Climate Panel says greenhouse gas emissions are warming the planet and will lead to more floods, droughts, heatwaves, rising sea levels and animal and plant extinctions.

World emissions have risen by about 70 percent since the 1970s.

Australia first held Earth Hour in 2007 and it went global in 2008, attracting 50 million people, organizers say. WWF, which started the event, is hoping one billion people from nearly 90 countries will take part.