Skip to main content

The methane conundrum

News | Published  19 May 2019

A vital biological process versus the perils of climate change.

Producers

In this article we hear from Dr Angela Wright. Angela is Chief Scientific Adviser at Compassion in World Farming (CIWF). Angela is also a Director of the Pasture Fed Livestock Association (PFLA).

In the past, Angela has been a small-scale producer of Norfolk Horn sheep, reared in a manner sympathetic to both organic and pasture-fed principles. Angela tells us more about the relationship between cattle and other ruminants and the environment:

The debate about environmental benefits – or not – of various methods of cattle production is really vexing me from a hard science/basic biology perspective in my day job at CIWF and my PFLA Director role too.

Methane emissions are a sign of the proper-working of the unique function that makes cattle and other ruminants what they are: superb digesters of plant material.

The rougher the forage the harder the rumen bacteria have to work, yet the more ‘value’ they add in the conversion to meat and milk equation. Indeed, this is possibly even more beneficial to the animal as they have a greater supply of protein in the form of the dead bacteria for their own nutrition.

So, it worries me when we look at ways to reduce their methane emissions, because that potentially means we are upsetting this exquisitely-balanced system. Indeed grain is a prime example: cattle fed on grain have lower methane emissions but suffer from rumen acidosis (if anyone has had a stomach ulcer or suffer heartburn regularly will know from a welfare perspective this is bad for the cattle – but apparently better for the environment in methane emission terms). It seems to me anything that significantly reduces methane production is probably not good for the animal.

The carbon cycle and methane

In terms of the carbon cycle and the short-term effect of methane in the environment – eloquently articulated by scientists from Oxford University’s Environmental Change Institute. I agree with the argument that a steady ruminant population does not, in principle, influence climate change processes but in a world afflicted by climate change caused directly by human activities there are real world consequences to the growing global ruminant population. Small island nation states being a prime example – they may simply cease to exist – peoples’ homes and livelihoods gone if global warming can’t be limited/reversed: I have first-hand experience of their concerns from UN meetings such as the Global Pact for the Environment in Nairobi in January this year and can understand why growing global cattle populations cause concern, particularly where this is associated with land use change and grain-feeding. Both substantially increase carbon loss to the environment with grain feeding responsible for loss and degradation of ecosystems and soils as well as air and water pollution.

The science used to support the overall neutral life-cycle of methane only applies to a stable number of ruminants also clearly shows that if there is an increase in population the ‘new’ methane has a harmful effect and contributes to global warming; it also shows that a small percentage reduction in methane (such as the reductions achieved by tinkering with the diet of cattle) has no significant effect in global cooling; however, a huge cut in methane emissions from a significant reduction of global ruminant numbers would make a significant contribution to global cooling. This is before we factor in carbon loss from land use change for grazing ruminants, particularly in South America, and grain-feeding in may parts of the world.

The old rules don’t apply in quite the same way now systems such as the carbon cycle are so completely out of balance and solutions are not simple. Any GHGs left floating around in a reactive state in the atmosphere are harmful, irrespective of source, and these sequestered in soil or bound up in plant material, whether that is grass or trees (or in situ fossil fuels) are not impacting on the reactions taking place in the atmosphere.

Grass-fed beef and lamb production could become climate-neutral when combined with suitable mitigation methods.

However, all is not lost for grass-fed ruminants produced in a climate-responsible way, including cattle. Matthew Jordan (also of Oxford University) suggests their production could become climate-neutral when combined with suitable mitigation methods. The Pasture Fed Livestock Association are an example of a group of producers with a system that delivers other significant benefits such as a net input into the food system, benefitting food security and increased biodiversity from the holistic approaches adopted by their Pasture for Life standards. Indeed other recent reports on sustainable food systems and healthy diets such as Grazed and Confused and the Eat Lancet Report show there is a small niche in a sustainable food system delivering heathy nutrition for pasture-fed meat. The ‘better’ in the eat less and better meat message.

Not all beef and lamb production is equal

We must remember, not all ruminant production is equal and global ruminant populations are rising. Not all pasture-fed ruminants are as climate-responsible as the type of sustainable regenerative approach I am talking about here and exemplified by the PFLA in the UK. Even then, additional global-warming mitigation activities should be incorporated to enhance those of carbon sequestration from grazing. Rewilding areas where appropriate will help, there is no doubt about that; silvopastoralism and afforestation/reforestation are also clearly a big part of the solution and organisations such as the PFLA are part of that suite of solutions. There is no single, one-size-fits-all solution: this is certainly clear from my experience working at a global as well as local policy level.