Dangerous things, cows.

T.S. Eliot feared and distrusted them, as revealed in his recently rediscovered poem:

Of all the beasts that God allows

In England's green and pleasant land,

I most of all dislike the cows:

Their ways I do not understand.

Henry Ford, the US car magnate, considered cows the most crude and inefficient machines, and spent much of his life campaigning against them: “We don't need cows,” he said.

And now poor David Blunkett has been trampled by an irate cow in the Peak District, bringing the number of people injured by cows in Britain over the past eight years to 481.

But the real threat from cows comes not from their horns, or that creepy rolling thing they do with their eyes just before they charge, but from their digestive systems: cows are flatulating the world towards oblivion. Daisy and Buttercup may look picturesque, and taste delicious with a little Béarnaise sauce, but each cow is a living factory chimney, spewing out pollution at a quite staggering rate.

Cows, according to a recent UN report, release more greenhouse gases, from both ends, than cars, buses, trains, planes and all other forms of human transportation combined. Cattle produce some two thirds of ammonia emissions, which cause acid rain, and are responsible for more than a third of all methane gas released as a result of human activity, mostly though bovine burping. Cattle eructate an estimated 60 million tonnes of methane globally every year, three quarters of all livestock emissions, and methane is 23 times more potent than CO2 as a heat-trapping gas.

The global-warming sins of the 4x4 SUV begin to seem almost mild compared to the malodorous eructations of the average Friesian, particularly when one takes into account the deforestation of land to make way for cattle, the fuel burnt to make fertiliser to grow cattle fodder, and the 16,000 litres of water need to produce a single kilogram of beef.

And the noxious cow-cloud hanging over the globe is about to get much worse. In developing countries, consumption of red meat has risen by a third in the past decade and the production of milk and beef is set to double in the next 30 years.

The UN is unequivocal - animal gases pose a big threat to the world's chemical balance, yet agricultural emissions have been largely overlooked in the global-warming debate. Because cows have formed part of our mental landscape for so long, a cow is seen as “natural” in a way that a Land Rover or a cement works is not.

Industries such as power generation, construction and car manufacture face enormous pressure to reduce emissions, but large-scale farming does not. Billions are being spent on engineering new, less polluting cars, while very little is spent on engineering new, less polluting cows. The UN finances more than 2,000 green projects; only 98 of these are agricultural.

The simplest way to reduce the carbon hoofprint would be to cut global consumption of meat and milk. This is not going to happen: we are simply too wedded to our cheeseburgers and cappuccinos. There has also been talk of a “cow tax” on polluting cattle, which would certainly provoke a stampede among dairy and beef farmers.

Instead, as in the car industry, a combination of technological innovation, government incentive and public pressure should be used to change how cows are farmed.

There have been some remarkable, although seldom reported, scientific breakthroughs in this regard already. Geneticists are working on ways of improving bovine digestion to reduce gas emissions, in a way that would have delighted Henry Ford. In the Netherlands, farms have developed ways to heat manure and trap the methane in it to make electricity for the local grid. In Sweden, food products are labelled so that shoppers can compare the emissions per pound of different meats.

A recent report in The Proceedings of the National Academy of Sciences concluded that if one million cows were treated with a single hormone to increase milk production, the environmental effect would be equivalent to taking 400,000 cars off the road.

Meanwhile, scientists are scrambling to produce synthetic meat in laboratory conditions using cell-culture technology. The Dutch Government is sponsoring a £2million project to try to cultivate pork flesh. Synthetic meat may sound disgusting, but Churchill predicted it in 1936: “Fifty years hence,” he said, “we shall escape the absurdity of growing a whole chicken in order to eat the breast or wing, by growing these parts separately under a suitable medium.”

The most fertile area of investigation is in changing cattle diet to render them less burpy. Groupe Danone (the French yoghurt folk) found that cows emit less methane in the spring. (There is a technique for measuring bovine wind. I shall not describe it. It is very French.)

Spring grasses are higher in omega-3 fatty acids, which seem to help the cow to digest better. Several experimental cattle farms have begun feeding the animals year-round on foods rich in omega-3, such as alfalfa and flax, rather than soy or other traditional fodders. Preliminary results suggest that the cows are healthier, produce more nutritious milk, and emit around 18 per cent less methane.

Government subsidies for greener cows and public awareness of the emissions involved in meat production will all help to transform our relationship with the steak, yet the final hurdle is cultural. Unlike Eliot, Ford and, presumably, the bruised Mr Blunkett, most of us like cows. But the vast global cattle herd needs to be seen as a rapidly expanding part of a delicate global organism - tasty, useful and familiar, but potentially highly damaging.

It is time to wake up and smell the methane.

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