Crowds began pouring into Wembley Stadium for the London leg of the seven-continent Live Earth concerts today.
The concerts - the brainchild of former US vice president Al Gore - are also taking place in New York, Washington, Sydney, Rio De Janeiro, Johannesburg, Tokyo, Shanghai and Hamburg.
The London concert opened with a supergroup consisting of members of the Foo Fighters, Red Hot Chili Peppers, and Roger Taylor from Queen.
Today's highlight is expected to be Madonna's headline act, where she will sing 'La Isla Bonita' and 'Hung Up', as well as a new song, 'Hey You', written especially for the event.
Other acts in London include newly reformed Genesis, Razorlight, Snow Patrol, the Black Eyed Peas, Duran Duran and James Blunt.
The concert comes just a week after Wembley Stadium played host to the concert for Diana, which also had Duran Duran on the bill - but this time music fans were treated to sunny skies.
The stadium pitch, covered in seating for the Diana concert, was this week full of hundreds of dancing music fans.
Live Earth has come under flak from detractors who believe getting in jet-setting stars, whose concerts and lifestyles generate large carbon footprints, is not the best way to illuminate the problem of global warming.
Organisers say the power used to put on the Wembley concert is being sourced from renewable energy.
Special guests at Wembley include former tennis star Boris Becker, actress Penelope Cruz, 'Extras' and 'The Office' creator Ricky Gervais and 'Doctor Who' star David Tennant.
Here is the set list for today’s Live Earth concert at Wembley:
1.30pm: Opening with Taylor Hawkins from the Foo Fighters, Chad Smith from the Red Hot Chili Peppers and Roger Taylor from Queen.
1.40pm: Genesis, playing 'Turn It On Again', 'No Son of Mine' and 'Land of Confusion'.
2.10pm: Razorlight, playing 'Before I Fall to Pieces', 'Los Angeles Waltz' and 'America'.
2.35pm: Snow Patrol, playing 'Open Your Eyes', 'Shut Your Eyes' and 'Chasing Cars'.
3pm: Damien Rice and David Gray, playing 'Babylon', 'The Blower’s Daughter' and 'Que Sera Sera'.
3.25pm: Kasabian, playing 'Empire', 'Club Foot' and 'LSF'.
3.50pm: Paolo Nutini, playing 'Wonderful World', 'Last Request', 'New Shoes' and 'Jenny Don’t be Hasty'.
4.15pm: Black Eyed Peas, playing 'Let’s Get it Started', 'Don’t Phunk With My Heart', 'Big Girls Don’t Cry' and 'Where is the Love?'
4.40pm: John Legend, playing 'Ordinary People'.
4.45pm; Duran Duran, playing 'Planet Earth', 'Ordinary World', 'Sunrise' and 'Falling Down'.
5.15pm: Red Hot Chili Peppers, playing 'Don’t Stop', 'Dani California', 'So Much I' and 'By the Way'.
5.45pm: Bloc Party, playing 'Hunting for Witches', 'Banquet', 'So Here we Are' and 'The Prayer'.
6.10pm: Corinne Bailey Rae, playing 'I’d Like To, Put Your Records on' and 'Mercy Mercy Me'.
6.30pm: Terra Naomi, playing 'Say It’s Possible'.
6.35pm: Keane, playing 'Everybody’s Changing', 'Somewhere Only We Know' and 'Is It Any Wonder?'
7pm: Metallica, playing 'Enter Sandman' and 'Nothing Else Matters'.
7.30pm: Spinal Tap, playing 'Stonehenge', 'Warmer than Hell' and 'Big Bottom'.
7.55pm: James Blunt, playing 'Same Mistakes' and 'Wisemen'.
8.20pm: Beastie Boys, playing 'Sabotage', 'So What’cha Want', 'Sure Shot', 'Intergalactic' and 'Off the Grid'.
8.50pm: Pussycat Dolls, playing 'Buttons', 'I Don’t Need a Man', 'Feelin’ Good', 'Stickwitu' and 'Don’t Cha'.
9.20pm: Foo Fighters, playing 'Best of You', 'All My Life', 'My Hero', 'Times Like These' and 'Everlong'.
9.50pm: Madonna, playing 'Hey You', 'Ray of Light', 'La Isla Bonita' and 'Hung Up'.