When you want to find a solution to a political problem, do you turn to experts, or actors? I ask because Stella McCartney is angry with Gwyneth Paltrow — about a subject neither of them understands. They are arguing about cruelty to animals this time: Gwyneth has been pictured wearing fur. But it could just as easily be global warming, or Darfur, or penguins, or handbags.

Stella is concerned about animals. I am too. But Stella — have people ever crossed your mind? You design clothes for H&M and Adidas. Would that be the same Adidas who has been accused in the European Parliament of handing out contracts to Indonesian factories that use child labour? The same H&M whose Indian supplier recently confirmed that wages paid to garment workers were as little as £1.13 for a nine-hour day? Indeed, you got rich in an industry that is built on making women feel like beach balls, where skeletal models are partly responsible for the epidemic of anorexia and bulimia sweeping the West. And you dare to lecture us about fur?

And, Stella, you are not alone. Sienna Miller is a spokeswoman for the charity Global Cool. Last year she went to Mumbai to tell the natives: "If each one of us does our bit, we will be able to keep global warming from harming our countries." She flew there. She later announced on Radio 4 that, "as an actress" she simply couldn't stop flying, but she will take slightly cooler showers.

Then there is Naomi Campbell, the angry string bean who is also a supermodel. She signed up to front PETA's I'd Rather Go Naked Than Wear Fur campaign, and was duly pictured naked. Then she decided she liked wearing fur after all, and was pictured wearing a fur-lined jacket.

And on the list of imbeciles goes. John Travolta came to London fretting about global warming. "Everyone can do their bit," he said. "But I don't know if it's not too late already."

He should know. He came in on his private jet. He has five of them. He parks them in his garden. The Carbon Trust pointed out that Travolta's carbon footprint is one hundred times that of the average Briton. "Night fever, night fever" — sing it for the planet, not for Travolta. And so on to Chris Martin. He is a celebrated fair trade campaigner who writes fair trade mantras on his hands in Biro and writes songs with lyrics like "Sunlight opened up my eyes ... and tonight rivers will run dry ... hundreds of years in the future ... there could be computers looking for life on earth ... don't fight for the wrong side ... ask, who does this belong to?" (He has also remarked that Nazi Germany might not have existed if Hitler had listened to Bob Marley, and urged Dick Cheney to listen to Radiohead.) This is all wonderful, except he uses a private jet to fly home between gigs and his daughter Apple often joins him on tour. By plane.

Global warming is desperately urgent. Animal cruelty matters. But we need serious people to tell us about it — not skeletal, surgical simpletons who will drop their fair trade pins to the floor on entering Heathrow's Terminal Five.