Myth No. 1: That cattle produce new loads of carbon to the atmosphere
Myth status: Simply not true
All of the carbon atoms that ever get into a cow – or any other ruminant animal for that matter – come from the atmosphere in the first place. They get into the cow’s body because the cow eats grass and grass gets its carbon by photosynthesis from the atmosphere. The carbon in a plant comes from the ‘sky’ not from the ground.
Any carbon the cow gives out – whether in the form of carbon dioxide or methane – is just a return of carbon to the atmosphere again. And the important thing is that this carbon had to be in the atmosphere before the cow was ever born, otherwise its mother could have never existed, could have never produced milk, and could have never protected the calf when it was young.
This is a completely different situation from the carbon put into the atmosphere by a coal burning power station or a motor vehicle. This carbon comes from deep in the ground where it has been sequestered for millions of years. The power station burns the carbon and dumps the new carbon dioxide in the air. The power station cannot re-use its carbon dioxide waste product. The cow can recycle its carbon dioxide by simply eating the next blade of grass!
You can stand at the top of the chimney stack of a power station and have an argument about whether this new carbon dioxide is warming the earth. You cannot stand in a yard of sheep or cattle and have the same argument.
Myth No. 2: That methane is an unusual, bizarre or dangerous gas
Myth status: Not true
Natural and organic methane coming from natural and organic processes – such as the decomposition of plant material in any environment – is a natural process which has been taking place on a vast scale for millions of years. Organic methane from cows is an entirely natural process, not man made at all. After a period in the atmosphere the carbon atom in a methane molecule undergoes a chemical change to become a carbon atom in a carbon dioxide molecule – exactly the same gas as it was before the whole process of photosynthesis started.
The chemical formula for this change in state from methane to carbon dioxide is:
CH4 + 2O2 = CO2 + 2H2O + energy (mostly heat) released
Some of the organic methane released by cattle and other livestock is consumed by living organisms as their energy source. These are the methanotropic bacteria. In some circumstances the amount of methane consumed by the methanotropic bacteria in any particular landscape can be greater than the amount of methane produced by a herd of cattle grazing the same area of landscape.
Myth No. 3: Methane is a more potent greenhouse gas than carbon dioxide
Myth status: True but, so what?
Depending on how you do the maths, and what assumptions are made in the formulas, methane can generally be regarded as a more potent greenhouse gas than carbon dioxide. The figure generally used by the IPCC is that it is 25 times more potent. The ‘so what’, however, is that the methane has always existed in the biosphere. It is a natural and organic gas. It has always existed in large quantities due to the action the cellulous in plants being broken down by bacteria. As the methane is constantly being produced, it is also constantly being converted to carbon dioxide or consumed by methanotropic bacteria.
The organic methane produced by ruminant animals has been a natural feature of the atmosphere since long before the Industrial Revolution.
Myth No. 4: That taking cattle out of the landscape reduces methane production
Myth status: Not true
Methane is an inevitable consequence of the sun shining on the earth and the water cycle, plant growth and animal life the solar energy drives. If cattle are taken out of a landscape, huge amounts of methane are still produced because something else breaks down the cellulous that the cattle would have eaten. Methane will be produced by whatever eats and digest the cellulous. Methane is produced in huge quantities in rain forests, wetlands and waterways where there are no cattle present.
Ultimately it is the sun that drives the production of methane in the plant and animal kingdom.
Myth No. 5: Methane will be reduced if we can just feed the cattle different food
Myth status: True in the first instance, but meaningless
A cow fed on easily palatable feed – not tough cellulous – will produce less methane per day than the same cow fed on tough rangeland cellulous. But this becomes meaningless because, if the cow does not eat the tough cellulous in the rangeland situation, something else will.
If tough cellulous is left to stand in a rangeland area, large amounts of it will be eaten by something else – such as bacteria, other animals and insects. The digestion of the cellulous in these other life forms will produce methane. It is estimated that around 80 per cent of Australia’s entire methane production comes small insects in the landscape called termites. What the cattle don’t eat, the termites will.
Trying to reduce methane production from a landscape in this way only results in a situation similar to cost shifting in a business accounting system.
Should Meat be on the Menu? by David Mason-Jones is available from August 1. Click here for details.
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