Image 20160321 30921 1k66rlx

To reduce greenhouse gases from cows and sheep, we need to look at the big picture

Livestock ‘digestion’ produces nearly 3 billion tonnes of greenhouse gases each year. Cattle image from www.shutterstock.com

To reduce greenhouse gases from cows and sheep, we need to look at the big picture

Farming livestock – cattle, sheep, goats, pigs and chickens – contributes around 6 billion tonnes of greenhouse gases (carbon dioxide, methane and nitrous oxide) to the atmosphere each year. While estimates vary, this could represent up to 18% of global emissions.

But the livestock sector also offers great benefits. It includes 20 billion animals, supports 1.3 billion farmers and retailers, and contributes up to half of the economic product from agriculture. The consumption of meat, milk and eggs is projected to grow 70% by 2050, mostly in the developing world.

Our study, published in Nature Climate Change, reveals that the global livestock sector can maintain the economic and social benefits it delivers while significantly reducing emissions. In doing so it will help meet the global mitigation challenge.

Livestock around the world

Around 1.6-2.7 billion tonnes of greenhouse gases each year, mostly methane, are produced from livestock digestion. Another 1.3-2.0 billion tonnes of nitrous oxide come from producing feed for livestock. And the final 1.6 billion tonnes comes from land use changes, such as clearing for animal pastures.

Emissions from livestock production vary across the globe. The developing world accounts for 70% of emissions, mainly because of the large numbers of animals used for a variety of purposes beyond production of meat, milk and eggs.

Greenhouse gas emissions from global livestock 1995-2005. Red areas represent more greenhouse gases. Herrero et al 2016 Nature Climate Change

The emissions intensity of producing livestock products (the amount of greenhouse gas that goes into producing a kilogram of protein) also differs significantly between regions. The developed world has lower emission intensities than the developing world due to the use of better feeds and management practices.

There are also large differences between livestock products. Poultry and pork products produce fewer emissions per unit of product than milk, and all these produce less than red meats.

Reducing emissions

It seems likely that emissions from livestock could be reduced by around 2.4 billion tonnes of greenhouse gases each year through technology and management.

Achieving these savings will be dependent on improvements in feeding practices (better pastures, new types of food, more grains and others), improved ways of handling manure, and improved genetics and animal management. Many of these strategies are based on sustainable intensification: producing more livestock protein with fewer resources; and storing carbon in the land.

Much less is known about the costs. This is in part a consequence of uncertainty about technology development and local costs. But we need to make sure the costs of reducing emissions are balanced with the benefits of livestock production.

Policy changes will also be important. Adoption of many practices that reduce gross greenhouse gas emissions has been low (10-30% of producers) due to poor incentives.

Unfavourable credit conditions, lack of markets, and/or systems for rewarding environmental performance are all hurdles. Our analysis highlights that global efforts should take these important areas into account when considering options to maximise return on mitigation investments.

The balancing act of using land

The livestock sector is connected to many other sectors using land and resources, so targeting livestock alone won’t work.

One of the key potential benefits of livestock mitigation is that many of the ways to reduce emissions could spare land, especially if this is associated with a reduction in animal numbers and a switch to fewer but more productive animals.

The spared land could be used directly for increasing food production for humans, for biofuels, or for replanting forests, for example.

All of these require incentives and public and private economic instruments to ensure livestock producers do not lose as a result of changes in practices. We also need to make sure producers don’t expand operations, if it pays to implement profitable practices!

What is certain, is that mitigation efforts in the land use sector need to be coordinated for them to be effective. It will be a game of carrots and sticks to ensure we get this right, and this is an urgent area of continuous research.

Eat less meat?

The elephant in the room is whether we should be looking to transition away from eating meat. We found that, in theory, this practice could mitigate up 5-6 billion tonnes of greenhouse gas emissions in the most extreme scenarios.

But as with many interconnected systems there is rarely an easy answer. In the developing world for instance, where lack of some nutrients and too many of others can occur at the same time, the problem is more complex. The question becomes about who keeps on eating and who should reduce consumption, and which products and where.

These issues are highly localised and therefore require local policy responses and action. With such an interconnected sector contributing 40-50% of agricultural GDP and to significant employment, poorly planned transitions in the global food system could have serious negative consequences in terms of the Sustainable Development Goals.

We can get the best mitigation potential from the livestock sector if we take a wide view of land use and practise change that considers the whole of agriculture and forestry, as well as looking at dietary patterns and how we meet the needs of global nutrition.

Sustainable intensification of livestock can reduce greenhouse gas emissions, but it will require better management, economic incentives and well-designed policies.