Madonna performs during the Live Earth concert at Wembley Stadium in London, July 7, 2007. [Reuters]

They rocked the world, but as the clean-up at nine climate change gigs around the globe begins, many wonder if the galaxy of pop stars did much to change it.

U.S. and British media were generally underwhelmed on Sunday by Live Earth, the mega-concert organized by former U.S. vice president and green campaigner Al Gore, which, though built on the model of Live Aid and Live 8, created a less positive buzz.

In Germany, however, newspapers were more upbeat about Saturday's gigs designed to pressure leaders to sign a new treaty by 2009 that would cut global warming pollution by 90 percent in rich nations and more than half worldwide by 2050.

Several articles examined the green credentials of artists on the day, including Madonna, whose annual "carbon footprint" was estimated at around 100 times the average Briton's.

The News of the World tabloid, Britain's biggest-selling newspaper, detailed estimates of Madonna's carbon emissions from nine houses, a fleet of cars, a private jet and the Confessions tour, calling her a "climate-change catastrophe."

The Sunday Telegraph quoted U.S. reports of her alleged financial links to companies accused of being major polluters.

Her spokeswoman in Britain was not immediately available for comment, but in a statement appearing in the Independent on Sunday, her New York spokeswoman said:

"Madonna's agreeing to sing at the Live Earth Event is merely one of the first steps in her commitment towards being environmentally responsible."

The negative headlines took some gloss off Madonna's widely praised appearance at Wembley Stadium in London, where she sang her specially written anthem "Hey You" before a raunchy performance of three of her biggest hits.

MIXED MESSAGES

The New York Times' online edition on Sunday featured a small picture of the event and a headline linking to "Artsbeat Blog," and in Britain only the Independent on Sunday made anything more than a fleeting reference on its front page.

But in Germany, where Snoop Dogg was among the acts at the Hamburg gig, Live Earth dominated headlines.

"The bottom line is that if nothing else, the issue of climate protection was a lot of fun for two billion people for one day," wrote Bild am Sonntag, Germany's best-selling Sunday newspaper.

Organizers say that in addition to the tens of thousands of fans at the gigs, the television, radio and internet audience could be as large as two billion.

Commentators noted the difficulty in marrying pop music with serious themes like the environment.

"Mixing music and a serious message gives concert a clunky rhythm," was the Washington Post's description of the Wembley gig, arguably the biggest lineup on the day that featured Red Hot Chili Peppers, Metallica and the Foo Fighters.

Performances were interspersed with long gaps, some of them filled by short films on environmental themes.

Many performers were "on message," calling on crowds from Sydney and Tokyo to New York and Rio de Janeiro to cut down on their personal carbon dioxide emissions and recycle.

Yet U.S. comedian Chris Rock expressed the kind of disbelief shared by many on the day that Live Earth would make a lasting difference, even if he was only joking:

"I pray that this event ends global warming the same way that Live Aid ended world hunger," he said in London.