If you want conclusive proof that comedy and stadium rock don't mix you only had to glance at the coverage of Live Earth on Saturday. While Madonna stormed it, most of the hotshot comedians who introduced the acts struggled to take control of the vast space. After last week's dismal Di performance it was ironically only Ricky Gervais who got away with it by keeping it short and sweet when he introduced the briliantly wrinkly Spinal Tap (or at least director Rob Reiner, in the guise of Tap rockumentarist Marty DiBergi). And by the way, surely a highlight of the day was the massed ranks of celebrity guitarists joining Tap for a rendition of Big Bottom. Don't ask me who the guests were though – the BBC was screening some pre-recorded nonsense from Tokyo while that piece of rock-comedy history was happening.

As for the other comedians on the day, if I'm brutally honest it is hard to make a sofa-based conclusive judgment about their performances. The transmission of Chris Rock's intro for the Red Hot Chili Peppers was abruptly truncated after he said a mother-upsetting rude word, resulting in a quick cut to a visibly distracted compere Jonathan Ross (what was he up to? checking his bank balance?). Others didn't even get as much coverage as that. While Russell Brand was doing his turn in front of the masses the Beeb was busy making Ross earn his fat cheque in his comfy corporate suite.

Then again, maybe it was a good thing that we saw more of the comics gagging with Ross and Graham Norton offstage rather than gigging onstage. Stand-up and stadium benefits are uneasy bedfellows. The average gagsmith's default setting is world-weary cynicism and this was a day for save-the world sincerity. It made more sense that the Pussycat Dolls and James Blunt rather than Alan Carr and Dara O'Briain earnestly told us to stick long life bulbs in our sockets. If Jimmy Carr (who looked oddly like an oily Roger Federer this weekend) mentioned long life bulbs he'd probably be making a joke about where else we should stick them. Fair play to Eddie Izzard though, at least he has a bit of previous where the eco-case is concerned, having voiced recycling ads.

Comedians are supposed to be society's dissenting voices, so when a weighty establishment figure like Al Gore puts the case for saving the environment it is only natural that comedians should take an opposing stand and they could hardly do it at Wembley (though David Baddiel tried, by calling himself a Climate Change Denier – shame he fluffed his line and Freudianly nearly called himself a Holocaust Denier by mstake). So maybe it was good that the BBC failed to feature the greatest wits of our generation doing their bits onstage. If there is one thing worse than the BBC's coverage of Live Earth it is comedians taking themselves seriously. Or maybe the BBC, in its infinite wisdom, agrees with me that comedians don't work in stadia and that's why they edited them out. Somehow, though, I doubt it.