The global chain of concerts designed to raise awareness on the global warming phenomenon kicked off on Saturday drawing hundreds of thousands of people.

The 24h gigs opened in Sydney with a traditional welcome ceremony by Australian Aboriginal dancers. Al Gore, the man behind the event and America’s former Vice President, appeared in front of the crowd by video, delivering greetings and urging fans to fight against global warming.

The Tokyo concert started with a laser/light show by virtual-reality act Genki Rockets, and also featured Japanese singer Ayaka.

A hologram of Gore delivered the purpose of the global concerts.

"With Live Earth, we hope to connect people through the power of music and engage them with a simple universal message: SOS. Answer the call."

"This is not just about raising awareness but letting every individual out there know that they too can do something about the scourge that is global warming,'' Bloomberg quoted Live Earth promoter Mark Pope as saying in a telephone interview from Sydney. "Music has always been good at promoting issues like this.''

The 45,000 concert attendees who flooded the Aussie Stadium in Sydney will hear sets from rock band Crowded House, American folk singer Jack Johnson, and local performers Missy Higgins and Wolfmother.

Events are also being held in New York, London, Rio de Janeiro, Tokyo, Shanghai, Johannesburg and Hamburg. The full round of concerts will be broadcast live on the Internet and on television aiming to reach an estimated 2 billion people.

Madonna, Metallica, the Police and Kanye West are among the top billed of more than 150 acts due to appear in the planet's biggest show to date and history's most ambitious benefit event, eclipsing Live Aid in 1985 and Live 8 in 2005.