People in more than 120 countries and regions have switched off their lights to mark the fourth annual Earth Hour. Organizers hope the event will re-energize efforts to strike a binding pact on curbing carbon emissions.

The Forbidden City joined the Earth Hour Action Saturday night.

At 8:30 P.M., Beijing time, the 600-year-old imperial palace turned off its lights.

In Hong Kong, its iconic skyline dimmed, after more than two thousand and four hundred buildings and companies joined the action.

Landmarks along Victoria Bay including the International Finance Center, the HSBC Building, and Hong Kong Convention and Exhibition Center, turned off their outdoor lights.

Elsewhere in the world, New Zealand switch off the lights at its parliamentary buildings in Wellington and the Sky City Tower in central Auckland.

The renowned white-shelled roof of the Sydney Opera House soon followed, together with thousands of buildings and countless homes across Australia.

The event continued throughout the world, as places who signed up to join the climate action, turned off their lights at 8:30 P.M. local time.

Andy Ridley, Earth Hour Founder, said, "It crosses all boundaries. So, it doesn't matter where you're from, what culture you're from, where you are geographically or economically, this is a one big problem that we all share and we are all part of the solution."

Citizens from more than 4,000 cities and towns across every continent switched off their lights for Earth Hour, the greatest display of collective action on climate change. The Earth Hour Action warns of the shortage of natural resources and tries to encourage people to live a low carbon lifestyle.

The north gate of the Forbidden City is seen before the "Earth Hour" in Beijing, capital of China, March 27, 2010. [Xinhua]