I have just completed the Australian online ‘Climate Change’ series of lectures. One of the contributors to greenhouse gases is farm livestock. I think sheep are being lumped in with cattle here, but it seems unfair and rather one-track minded to me. First off, the cattle whose methane output has been experimentally measured are all necessarily housed, in order to capture the methane given off. Secondly, in order to be housed they must be partially grain fed and partially fermented grass fed ie silage. These lead to abnormal gut flora so the methane output is unlikely to be comparable with outdoor cattle. Thirdly, outdoors the grass and surrounding trees will absorb a percentage of the methane given off, unlike gases collected in a closed shed, which would normally be vented directly into the atmosphere.
So, in order fairly to lump together sheep with cattle, the sheep would also need to be housed, and also fed grain and fermented forage. The same limitations on accuracy apply.
In addition I have observed that sheep produce nothing like the volume of gas that cattle do.
However, the main point I want to make is that these animals have valuable secondary ‘crops’ including skins from cattle and wool and skins from sheep.
Sheep’s wool in particular is surely the most eco friendly fibre around. If we cut back on the number of sheep bred, then wool will become expensive, perhaps on a par with the inevitable increases in costs of fibre made from fossil fuels. The worst culprit for high fossil fuel inputs and water usage is cotton. This crop is the greediest in the world, using enormous amounts of water, fertilisers, pesticides and herbicides in its cultivation, and on top of that are all the processing environmental costs too. People think of lovely natural cotton, but in fact its environmental cost is extreme.
I am positive that wool is the key to low impact fibre production for the future. Chemical and water inputs during cultivation are minimal, and all water used in cleaning the wool prior to processing can be cleaned and returned safely to the environment or reused - and of course the lanolin filtered off is yet another useful product.
Once turned into clothing, washing of woollen products can be less frequent, and the clothing, bed covers, furnishings etc will last far longer than fabrics produced from fossil fuel sources.
When we consider the methane output from these animals we should also take into account bigtime the production of wool, so food and clothing from one animal and one space - quite a bargain.
Incidentally, in these calculations of methane output from living things, I have not yet seen mention of, say, wild herds of bison, horses (domestic and wild) or in particular the SEVEN MILLION human beings living today - a whole lot of methane.
Also posted on Ravelry