Sydney, the home of Earth Hour, is preparing to celebrate the global environmental movement's second anniversary. In 2007, more than two million Australians took part in the symbolic event to draw attention to climate change. Organizers say more than 3,400 towns and cities in 88 countries will participate in this year's Earth Hour.
Scotland's Edinburgh Castle, the Bird's Nest stadium in Beijing and the pyramids in Egypt will join the Sydney Opera House in dimming their lights as part of Earth Hour.
The global event has been endorsed by the Secretary-General of the United Nations. Ban Ki-moon has said it was the biggest climate change demonstration ever attempted. Mr. Ban urged people everywhere to pressure their governments to take decisive action to cut carbon pollution.
Organizers are hoping that up to a billion people from small villages in Namibia to sprawling cities in Asia will participate in an international effort to cut greenhouse gas emissions, which many scientists blame for a warming climate.
One of the architects of Earth Hour, Andy Ridley from the conservation group World Wildlife Fund (WWF), says the current financial meltdown should not be used as an excuse to delay environmental reforms.
"The global economic crisis has proved that we are a global community, so when America goes bad, we all go bad and climate change is going to be on a scale that is way, way beyond our global economic crisis at the moment and we need to put in place the measures to a) slow that down and ideally halt it, b) be ready for economies that will have to change.  So, the longer we procrastinate the more we pay the penalty so we need to move quickly," he said.
Earth Hour was started by environmentalists in Sydney in 2007. It encourages households, businesses and governments to switch off all non-essential lights for 60 minutes in a show of unified concern for the health and future of the planet.
In two years, the event has become a large global movement and its aim is to create an enormous wave of public pressure that will influence delegates at a meeting in Copenhagen later this year, which hopes to establish a new U.N. climate treaty.
However, critics of Earth Hour have insisted it is simply a symbolic gesture that will not affect significant environmental change.
The event will officially begin on the international dateline in the remote Chatham Islands south-east of New Zealand and will conclude in Hawaii.