"If you want to save the planet, let me see you jumping up and down!" said Madonna as she opened her headline set.

It's often easy to scoff at celebrities at such events, and Saturday's was no exception. Whenever a great act was about to take the stage, the crowd would descend into a patient hush for another speech. Celebrities delivering nuggets of environmentalism included Boris Becker, Kyle MacLachlan and Ioan Gruffud, as well as Chris Moyles and Russell Brand.

In Pictures: Live Earth at Wembley Stadium

Chris Rock added to the sense that some lacked understanding of the scientific claims they were making with this statement: "Global warming means that every day in Jamaica, a little kid bursts into flames."

It was always going to be a challenge to present a soundbitefriendly take on such a highly complex topic.

The organisers achieved this aim admirably, with the 70,000-strong crowd experiencing a feeling of purpose that went beyond their love of music.

Still, unless they happen to be genuine wholemeal-dress-wearing tree-huggers, young people will seldom get as fired up about caring for the environment as they will about the imminent prospect of seeing Razorlight, the Red Hot Chili Peppers or Madonna.

The stadium was dramatically plunged into darkness before Madonna took the stage as actor Terence Stamp urged the crowd: "Let's not be endarkened by this. Let's be enlightened by this."

As well as being hammy and dull, Stamp's monologue arguably went against the spirit of environmentalism by inventing the verb "to endarken", rather than recycling one of the many perfectly serviceable words already in circulation.

By Madonna's standards, it was an inauspicious start. Hey You, the song she wrote specially for the event, was simply not up to scratch. Ray Of Light, however, was a reminder of just how powerful a performer she is.

The undoubted high point of her performance was the result of an inspired decision to perform a gypsy-tinged version of La Isla Bonita accompanied by the charismatic Eugene Hutz of Gogol Bordello and The Gypsy Kings' Sergey Ryabtsev.

Madonna remains full of surprises, helping to ensure that even in this age of ever-improving festivals, Live Earth has taken the art to a new level.

BEST OF THE REST

Red Hot Chili Peppers
Anthony Keidis and chums created genuine fist-pumping euphoria with the intense, uplifting By The Way. Bass player Flea poked gentle fun at some of the day's worthy platitudes by announcing: "I'm going to tell you the most important thing you've ever heard. Oh no, I've forgotten."

Corinne Bailey Rae
That her appearance heralded a burst of glorious sunshine didn't seem like coincidence. Bailey Rae's happiness was infectious. The highlight of her set was when she joined forces with John Legend for a tender rendition of Marvin Gaye's environmentally themed Mercy Mercy Me.

Metallica
The percentage of the crowd who'd come to see them must have been in single figures, but Metallica are purpose-built for to rock stadiums. Their brief set captivated the thousands, especially the overblown pomp of ballad Nothing Else Matters.

Spinal Tap
This group may have begun as a joke, but their set struck the perfect balance between comedy and singalongability. They created an unprecedented spectacle by bringing on stage the bass players from almost every other group to perform Big Bottom, a track written to celebrate large ladies.

Beastie Boys
The veteran experimental rappers steered clear of their oddball new material in favour of party-rocking hits like Intergalactic and So Watcha Want, working the crowd brilliantly.