Live Earth founder Kevin Wall, left, and former U.S. vice president Al Gore chat in New York. Wall, an Emmy-winning concert producer who produced Live 8, hopes Live Earth will change attitudes about global warming and spark a larger movement.

New York ? Live Earth is ambitious by any standard: eight concerts featuring the biggest names in music, playing for a 24-hour period across the globe, all for the cause of global warming.

But like its template – 2006’s Live 8, the global concert devoted to poverty in Africa – the mission of Live Earth is somewhat amorphous. Its aim is to “trigger a global movement to solve the climate crisis.”

Whatever Live Earth’s accomplishment on Saturday, it will be difficult to measure. Former Vice President Al Gore, who partnered with Kevin Wall in founding Live Earth, believes the world needs to rise up as one giant vox populi to influence “a new political reality.”

“The tipping point in the political system will come when the majority of the people are armed with enough knowledge about the crisis and its solutions that they make this cause their own,” Gore said in an interview with The Associated Press. “Then, you will see the entire political system shift dramatically.”

Kevin Wall, an Emmy-winning concert producer who produced Live 8 and founded Live Earth, hopes Live Earth will change attitudes about global warming and jettison a larger movement.

“This concert is not the solution,” Wall said. “This concert is providing, hopefully, that global tipping point to start to get us into empowering people, get them into the tent.”

“Maybe we can make the noise, maybe we can be the town crier, maybe we can say like Paul Revere, ‘The British are coming,'” he added.

Live Earth will send proceeds to the Alliance for Climate Protection, a nonprofit organization chaired by Gore (tickets for the U.S. concert range from $83 to $348). Wall was originally inspired to put on Live Earth after seeing “An Inconvenient Truth,” the Academy Award-winning documentary on Gore’s global warming slideshow.

“The question I kept asking myself is, ‘What can I do?'” Wall said.

Concerts are scheduled for Giants Stadium in East Rutherford, N.J.; London; Johannesburg, South Africa; Rio de Janeiro, Brazil; Shanghai, China; Tokyo; Sydney, Australia; and Hamburg, Germany. A band of scientists will also perform in Antarctica, stretching Live Earth across seven continents.

More than 150 artists will perform, including Madonna, the Police, the Red Hot Chili Peppers and Alicia Keys. Sixty short films and 30 public service announcements have been produced to be broadcast between performances.

Also planned are more than 6,000 parties in 119 countries – ranging from home viewings to museum festivals. The concerts will be broadcast in the U.S. on NBC, Telemundo, the Sundance Channel, Bravo, MSNBC and Universal HD. They also will be broadcast online at LiveEarth.MSN.com and on XM satellite radio.

Live Earth has been organized mindful of lessons learned from Live 8, which was planned just weeks in advance by Bob Geldof to rally support for Africa. Envisioned as a sequel to 1985’s Live Aid (which benefited famine in Ethiopia), Live 8 didn’t charge for tickets and generally kept to a vague message urging help for Africa.

The underlying point of Live 8 was to pressure world leaders who days later met for that year’s G-8 Summit in Gleneagles, Scotland. Some success could be claimed: The G-8 nations committed to increasing aid to Africa from $25 billion annually to $50 billion by 2010. The leaders also endorsed a deal to cancel the debt of 18 of the world’s poorest nations.

Since then, Geldof has created the Web site www.thedatareport.org to audit how faithfully the G-8 nations keep to their Gleneagles promises.

But Geldof has been critical of Live Earth. In May, he told a Dutch newspaper: “Live Earth doesn’t have a final goal.”

At a news conference last week, Gore and Wall mapped out some of their goals for Live Earth. They unveiled a “7 Point Pledge” that concertgoers will be asked to sign. Those who sign it promise to pressure their country to sign treaties to cut global warming pollution, personally reduce carbon dioxide pollution and plant trees, among other things.