More than 100 of the world's biggest names in music, including Red Hot Chili Peppers, Bon Jovi and Keane, will appear in a series of concerts to highlight the threat of climate change.
Former US vice president Al Gore announced that the 24-hour Live Earth event will feature star-studded concerts in London and six other cities around the world.
The other cities involved will be Shanghai, Johannesburg, Sydney and locations to be announced in Japan, Brazil and the US.
There will even be a concert in Antarctica.
Mr Gore introduced the event flanked by actress Cameron Diaz and rapper Pharrell Williams.
British bands set to perform include Snow Patrol and Bloc Party as well as Irish singer Damien Rice.
"We have to get the message of urgency and hope out," Mr Gore told a Los Angeles press conference.
"In order to solve the climate crisis, we have to reach billions of people. The climate crisis will only be stopped by an unprecedented and sustained global movement."
Other acts among more the performers scheduled to appear include the Foo Fighters, Lenny Kravitz, Sheryl Crow and the Black Eyed Peas. Williams said it would be "the biggest party on earth".
The proceeds will create a foundation to combat climate change led by The Alliance for Climate Protection, currently chaired by Mr Gore. The ex-politician's global warming film, An Inconvenient Truth, is up for two Oscars.
