Earth Hour founder Andy Ridley said, "The reaction to Earth Hour has been immense. It is so much more than last year. There appears to be some fatigue to the politics around it... But people are far more motivated this year than they were last year."
Earth Hour began in Sydney in 2007 when 2.2 million people switched off the lights in their homes, offices and businesses to make a point about electricity consumption and carbon pollution.
This year the switch off is being observed from 8.30 pm to 9.30 pm, on Mar 27, 2010.
Major multinational corporations including Google, Coca Cola, Hilton, McDonalds, Canon, HSBC and IKEA have endorsed Earth Hour 2010 and pledged to darken their offices worldwide in support.
WWF Indonesia said around 200 buildings in Jakarta would be taking part in the blackout.
Japan's heritage-listed Hiroshima Peace Memorial will take part, while major companies including Sony, Sharp and Asahi were to switch off across Tokyo.
In Dubai, the world's tallest skyscraper, the Burj Khalifa tower, will also dim its lights.
India first participated in 2009, when Delhi and Mumbai formally pledged to be involved. This year, along with Delhi and Mumbai, Pune, Ahmedabad, Hyderabad, Bangalore, Chennai and Kolkata are all participating.
Qutub Minar, Red Fort, Humanyun's Tomb and Chatrapati Shivaji Terminus to the symbols of modern India - hotels, cinema complexes and shopping malls, all expressed their commitment towards the cause and switched off their lights for that one hour.