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The Live Earth global concert series kicked off Saturday with an Australian Aboriginal group dancing and singing a traditional welcome at the first venue in Sydney.

Tribal leaders with white-painted bodies and shaking eucalyptus fronds were the first of more than 150 performers at the nine 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.

Gore invited the crowd — which appeared to be several hundred when the show started at 11:30 a.m. (9:30 p.m. EDT Friday) and scattered throughout the sporting stadium arena — to take Live Earth's seven-point pledge to reduce their personal environmental impact and support policies to reduce greenhouse gas emissions.

"Thank you for coming today and thank you for being the very first to launch this movement to help solve the climate crisis," Gore said, standing before the Capital building in Washington. "Enjoy the show."

The funk, roots act Blue King Brown took the stage shortly afterward — the first official band on the global bill. The worldwide lineup includes Madonna, Metallica, the Police and Kanye West.

Problems and changes to the series continued right down to the last minute, with a ninth concert — in Washington, D.C. — added on Friday and a court battle continuing in Brazil to decide whether the show there could go ahead as planned.

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.

"The last thing the planet needs is a rock concert," The Who's singer Roger Daltrey recently told a British newspaper.

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.

In Johannesburg, four-time Grammy nominee Angelique Kidjo offered a tart response to Daltrey's comment. "Criticism is easy," she said during a news conference Friday that involved performers in the local concert. "And there is a kind of fashion of cynical people around us. You are cynical — what the hell are you doing to change the world? Get your butt out there. Do something."

And it is beyond time to do so, she explained.

"Climate change is visible today, we can see that now. And if you can talk to farmers they will tell you that their crops that they are harvesting are not the same as before. That for me is a wake-up call because if we cannot eat, we cannot sustain ourselves. We don't eat cameras, we don't eat cars, we eat food."

More than 150 artists will perform at the nine concerts. Rolling west through Saturday, the series starts in Sydney, then Tokyo, Shanghai, Johannesburg, Hamburg, London, Rio de Janeiro, New Jersey and Washington.

The biggest names will appear in London and New Jersey, with more modest lineups of mostly local and regional acts in the other places.

Organizers were predicting live broadcasts on cable television and the Internet could reach up to 2 billion people. Scores of short films and public service announcements will be aired giving the audience tips about how to conserve energy and reduce their environmental impact.