Samstag, 27. Dezember 2008

fatal flatulence

Digesting the yuletide feast has made me aware of the forgotten frontline in our war on climate change.

Incredibly, 18% of greenhouse gasses are emitted from the business end of our livestock. This is higher than the percentage produced from all forms of transport combined. What's more, methane has 25 times the global warming potential of carbon dioxide, which means just
one cow annually emits the equivalent to driving 10 000 miles in an SUV.

A report in last week's New Scientist makes a number of suggestions.

Our farmyard friends could be vaccinated against the methane producing microbes which currently occupy their rumen (pregastric or 'first' stomach). These microbes have evolved as part of a chain of microorganisms which digest plant matter into first carbon dioxide and hydrogen, and then methane. The idea would be to identify the microbes responsible for methane, and knock them out without harming the others. They're getting close. Localised tests have lowered methane production by 8%, eventually the vaccinations are hoped to achieve 20-30% reductions. "It's very exciting" says one enthusiastic scientist...

Changes in diet could also produce results. Free range livestock typically produce 20% more methane than those reared in sheds because of their diets. The addition of legumes or unsaturated fats respectively could again lower emissions by up to 20% by speeding up the digestive process. Effects on flavour of milk and meat, or wellbeing of animal, are yet to be tested.

Most interesting of the suggested solutions is not tinkering with the gut of the cows and sheep, but getting rid of the cows and sheep all together:

Two Australian biologists say there is a sure-fire way to reduce methane emissions without resorting to complex biotechnology: cut the number of cattle and sheep being reared and meet the demand for meat with marsupials. Kangaroos produce barely any methane (see diagram) as their dominant gut flora are acetogens, not methanogens. These convert the hydrogen into acetate, a fatty acid that can also be used by cattle as an energy source. George Wilson and Melanie Edwards, based at Australian Wildlife Services in Canberra, have calculated that replacing a third of Australia's sheep and cattle with kangaroos would slash cattle emissions and reduce the nation's entire greenhouse gas output by 3 per cent. "It's not a completely wacky idea," says Wilson. "All [Australian] supermarkets already carry kangaroo meat on the shelf. It is a AU$250 million industry." Kangaroo burger anyone?

I've tasted Kangaroo and it's not too bad. Nice and lean. Of course this suggestion enters the dangerous territory of changing habits. Beef loving Europeans are about as likely to start eating Skippy as they are to stop eating meat all together.

Strangely, given that the main photo in the article seems to suggest something along these lines, the most innovative and intriguing possibilty isn't discussed. 'Cow power'
is already a growing industry in some places. It involves capturing the methane from decomposing manure and then using it as biogas. Why wait so long? My suggestion would be to strap a balloon to the back of every cow, sheep and pig in the Shire, plug a tube up it's backside, and tap the methane straight from the source, never even giving it the chance to sullen our atmosphere. Livestock would serve a dual purpose, both filling the stomachs of the rich and hungry, and powering their gas cookers and fridges.

In fact, why stop at the gates of the farm? We could all wear fartbagsTM, each of us going by our daily activities with huge balloons floating above us, emptied every evening into the household biogas burner. Farting would no longer be a social taboo, it would be the sign of good, ecological citizenship. I for one could probably light my flat for the whole of January thanks to this bloated post Christmas period.

Images from New Scientist No2687

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