Methane from cattle

You might have heard that there is no point in doing anything about reducing emissions from energy because cows emit far more greenhouse gas than people. Like many such statements there is a kernel of truth, but not much more.

It starts with methane, which is what natural gas is composed of. Methane is a potent greenhouse gas, perhaps twenty times more potent than carbon dioxide, but usually does not last in the atmosphere for longer than a year. In 1745 there were about 1000 parts per billion in the air, and today there are around 1850 parts per billion, so atmospheric methane has risen quite dramatically and the rise has coincided with the industrial revolution and massive population growth, both of people and cattle.

Methane gets into the air from the earth’s crust, volcanic action, the action of microbes, and from the enteric fermentation of cattle, sheep and goats.  Termites produce methane and as the ice at the poles melt pockets of methane which have been trapped under ice for thousands of years, are released into the atmosphere. Methane is also released from human industrial activities such as coal mining, wastewater treatment, natural gas and petroleum production. Although methane with its global warming potential of 21, is more invidious than carbon dioxide, it is in itself much shorter lasting and when burnt or degraded produces carbon dioxide. Methane also adversely affects the ozone layer.

Nature produces about 40% of the atmospheric methane released each year and the rest is down to human activities, which include cattle farming. It is hard to know what the global contribution of cattle is to methane production but in the United States, they estimate that 20% of US methane emissions are as a result of cattle.

Of course Americans are great meat eaters and it is likely that in the world as a whole significantly less than 20% of the methane produced is produced by cattle. In the United Kingdom, for example, 4.5% of greenhouse gas is apparently produced from cattle sheep and goats.

Cattle produce most of the methane by belching and only a relatively small amount by flatulence.

It follows then that we can reduce methane production by eating less meat and cheese and drinking less milk. We all probably eat too much meat, in any event.

Research at the University of Reading and the University of Aberystwyth’s Institute of Biological and Rural Sciences shows that ruminants will produce less methane if their diet is adjusted, the reductions ranging from 20% to 33% using different natural foods, but it is not clear whether the meat and milk production would be less with a different diet, and if it is there would simply be more cattle with each of them producing fewer belches. Overall methane production may stay the same.

The United Nations says that animal greenhouse gas emissions should be taxed, just as human greenhouse gas emissions should be taxed. It will be a confident government that taxes meat, anywhere in the world.

A better option would be for people to eat less meat.

 

One Response

  1. In fairness George Monbiot (left wing vegan activist) has debunked the greenhouse gas theory regarding animal methane emissions.

    You can find his piece on the Guardian website – http://www.guardian.co.uk

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