Stolen from The Guardian, with apologies to them, especially their science editor Tim Radford:

Scientists fume at call to avoid turkey

An Australian gastro-enterologist set the world of science fuming yesterday when he urged people to avoid flatulence-producing turkey and plum pudding at Christmas, to help save the ozone layer.

Terry Bolin of Sydney's Prince of Wales Hospital said:"There has been no real measurement of emissions from humans as a contribution to the ozone problem. But it probably does, because it's the hydrogen and carbon dioxide and methane that you produce that have an impact." The average person "emitted" a litre a day, he said.

But Dr Jeremy Leggett of Greenpeace said the real dangers of methane "lie not with farting Australians" but with bacterial digestive processes which have stored millions of tonnes of methane in frozen bogs under the tundra. "As the world warms, these will be released in quantities that will boost global warming and add to ozone depletion."

Professor Rodney Taylor of the British Digestive Foundation spoilt it all by pointing out that methane was produced by a high-fibre diet. Vegetarians were more likely to add to the methane crisis. "Just to put it into perspective," he said, "the average cow produces 500 litres of methane a day"

Professor Tom Wigley of the climate research unit at the University of East Anglia hit back. "Methane doesn't destroy ozone," he said. "Methane increases the amount of ozone. And so the more you fart - if you can get it up there into the stratosphere - the better it is for the ozone layer. "I did a little calculation on the greenhouse effect of extra farts over Christmas. If a billion people - which is about the Christian world - fart an extra two litres of methane a day for seven days over Christmas, that would produce one hundredth of a teragram of methane." A teragram is a million million grams.

"That's quite a lot of methane. But present emissions are about 500 teragrams so we are talking about an increment of only one fifty-thousandth. I worked out what the temperature effect would be. It would be about a hundred-thousandth of a degree Celsius. From a climate point of view, don't worry about farting. For the ozone layer, fart as much as you possibly can," Professor Wigley said.