Sheep are important. Sheep are amazing. I love sheep. Wonderful multi-functional creatures that provide, in addition to wool, meat, milk, cheese, skins, lanolin, tallow and many other products. Not to mention their enormous cultural, ecological and economic importance. All on four legs. All made from nothing but grass and so very beautiful.
In an earlier post on FSM I spoke about the amount of energy and water needed to in scouring a fleece at home. And it got me thinking. Just what are the environmental impacts of wool?
In our knowledge driven world, we know that all is not as rosy as it should be. The production of wool and the manufacture, use and disposal of the products we derive from it will have environmental impacts.
On the plus side wool is (mostly) a sustainable, renewable and low impact resource. Sheep don’t need massive inputs of artificial stuff, they get by on grass and can live in places that aren’t useful for other forms of agricultural production. Wool can keep us warm. Not just jumpers but also insulating carpets and insulation in our homes, reducing our need for heating energy. Wool is not a highly processed material. Its clipped from the sheep, scoured, organised and spun ready for use. Its reusable, recyclable (see Tom of Hollands great blog on re-purposing and mending) and it’s biodegradable. What else? Wool is also hygroscopic – that’s science for absorbs moisture – so it can keep you and your home low in humidity. Dragging the bottom of the barrel now – but I’m sure there’s more – let me know.
On the other hand the production of wool (more so in intensive systems) can use pesticides, fertilisers and, if housed indoors at any point, feeds. These all require energy, resources and emit greenhouse gases and produce wastes in their production and use. These include the use of organophosphate pesticides in sheep dip. If not managed sustainably overgrazing degrades land.
Wool scouring can use huge amounts of water – although information is difficult to find I have a figure of at least 5 cu litres of water per kilo of fleece. Fleece typically looses about 30 of its weight during scouring. Some of this is lanolin which is collected as a useful co-product but the remainder will be found in the effluent waste water stream. This waste water contains particulates and suspended organic matter (polite way of describing things such as pooh and dandruff) and residual pesticides and insecticides from ectoparasite treatments of the sheep (including organophosphates) and cleaning agents (this is covered really well in this post by Ecotextiles ). As does treatments of wool products for insect resistance and stain resistance.
Dyeing can also involve the use of toxic materials and can cause the pollution of water with heavy metals and other nasties (and natural dyes aren’t entirely off the hook here – some of the chemicals used as mordants are real nasties). And there’s the transport, all that southern hemisphere merino…
Actually putting numbers to the environmental impacts such energy, water, greenhouse gas emissions, land use degradation and toxic impacts of wool is difficult. A recent report (Understanding the Environmental Impacts of Wool) found that there were many problems. Firstly, wool is a secondary product to meat so how do you allocate the impacts between them? Secondly, supply chains are diverse both between and within countries. Thirdly, sheep farming covers a very wide range of geographic and climatic regions. Sheep farming practices are incredibly diverse. As are processing and manufacturing technologies and production efficiencies. And finally, there is very limited data available on wool production globally and very few studies. So, we simply do not have any usable answers to that question yet.
In my other life I recently came across a recent paper by Weidman et al (2015) which examined the environmental impacts of raising sheep in four case studies including one UK hill farm with a flock of Lleyn and Cheviots, one New Zealand flock of Romney and 2 Australian Merino flocks. The UK case housed flock in a barn for one month, the other 3 case studies were 100% pasture.
The study used an environmental assessment method called life cycle assessment (LCA) to estimate the environmental impacts the production of meat and wool from cradle to farm gate. I deal with LCA in my other life so this post is a bit two worlds colliding.
Here’s the science bit – feel free to skip to the punch line if this bores the pants of you.
The biggest problem with LCA studies in systems like sheep is that wool is not, in general, the only product. It is what is known as a co-product. The other dominant product is meat. So how do you separate the environmental impacts of a sheep’s fleece from its meat? Allocation is the thing. The impacts need to be allocated according to a specified ‘thing’. Allocation can be done in many ways. In systems like agriculture the most often used and easiest is by economic output (i.e £/kg). But the results will vary hugely between different markets and over time, so the results will be relatively unstable and difficult to compare. Interestingly this study allocated the burdens using biophysical allocation. Not as complex as it sounds. Impacts were allocated according to the percentage of total protein mass in the meat and the wool. This method produces more stable and reliable results. It’s based on actual sheep biology and not a spreadsheet of funny numbers that changes on a whim driven by a bunch of numpties sat in front of computers buying and selling stuffs they will never see. Clever hey.
In this study the production of a sheep was found to produce green house gas emissions of between 8.5 to 10.5 kg CO2-e per kilogram total (including wool and meat). This includes not just carbon dioxide but also methane – sheep eat grass, they digest grass, they fart – alot – and other greenhouse gases. I’ve played with the results and made some lovely charts showing greenhouse gas emissions as kg of carbon dioxide equivalent (kg CO2 e) and energy as MJ of oil equivalent (MJ oil-e) per sheep for biophysical and economic allocations. These two charts show the difference that allocation method can make.
When allocation was based on biophysical (protein content) the results for wool production are less variable between the four case studies. It would be great to see what a similar study based on the same sheep breed would show.
The UK has the lowest GHG impact and energy demand. This is even more pronounced when using economic allocation. Wool was only 4% of the total value of a sheep for the UK case compared with approx 50% for the Australian cases. As we all know, there is not much value in wool in the UK .
But of course what we don’t have is the rest of the lifecycle for wool. The shipping, scouring, processing in to lovely spinable fibre. I will keep digging and let you know what I find.
Wool is fabulous. Wool is the perfect material – almost. So what can you do to keep things just so? I guess the main thing is know where your fibre and yarn comes from. Can you source sustainably produced, organic fibre and yarns? Shift from imported sheep breeds and play with British breeds. There are now many producers that you can buy direct from. I’ve used Romney Marsh wool top and have my eye on some of Risby Granges Leicester Longwools.
Just look at Louise’s wedding dress! Just look at it!
Can you go even more local? Source fleece and fibre direct from the producer and support your local and regional flock.
Me, the most perfect thing I can do is to get on my bike in June to the farm down the road to get my fleece.
And don’t forget Wool Week is 5th – 11th October