Tribal leaders with white-painted bodies and shaking eucalyptus fronds were the first of more than 150 performers at the eight concert, 24-hour series to raise awareness about climate change.

The performance was immediately followed by a video greeting from former Vice President Al Gore, whose campaign to force global warming onto the international political agenda inspired the event.

Meanwhile, a ninth venue was added Friday to the global concert series whose worldwide lineup includes Madonna, Metallica, the Police and Kanye West.

The biggest names will appear at Live Earth concerts in London and the United States, with more modest lineups of mostly local and regional acts in Australia, Japan, China, South Africa, Brazil and Germany.

Live Earth was inspired and is backed by Gore's campaign to force global warming onto the international political agenda by generating a groundswell of public concern.

But critics say that it lacks achievable goals, and that bringing in jet-setting rock stars in fuel-guzzling airliners to plug in to amplifier stacks and cranking up the sound may send mixed messages about energy conservation.

Organizers say the concerts will be as green as possible, with a tally of energy use being kept. Proceeds from ticket sales will go toward distributing power-efficient light bulbs and other measures that will offset the shows' greenhouse gas emissions, they say.

More than 150 artists will perform at the eight concerts. Other venues are in Tokyo, Shanghai, Johannesburg and Hamburg.

But organizers were predicting live broadcasts on cable television and the Internet could reach up to 2 billion people.