It’s an easy mistake to make.
You feel confident about your food choices when someone tells you something about the food you’re eating that makes you wonder:
Am I making the right choice? Am I eating the right food for me? One that doesn’t cause global warming?
Think beef for now. How many times have you heard it is bad for the planet because cattle release methane?
Let me take all your worries away so you can enjoy eating beef for good.
Why do cattle produce methane?
Let’s start at the basics. Why do cattle produce methane?
Cattle are ruminants and their bellies are full of stomachs and guts. They house vast populations of bacteria that allow cattle to digest grass.
We cannot digest grass so we cannot appreciate how difficult it is. Only certain bacteria can digest grass. They ferment grass. As a by-product of this process, methane is released.
Cattle and methane misconception
Now let’s talk about methane. Methane is a greenhouse gas but it differs from CO2 in many ways.
What are the common misconception and what is the truth?
- Methane is worse than CO2 and causes more warming. True, methane has a higher warming potential. That’s what scientists talk about when a single molecule of gas in the air causes warming. However, methane has a short lifespan (12 years). It contrasts with a lifespan of CO2 – up to 200 years. CO2 also tends to accumulate whereas methane breaks down into CO2 in the atmosphere within 12 years (IPCC report). When broken down, methane has the same warming potential as CO2.
- Cattle are the biggest contributors of methane emissions on our planet. That’s incorrect. Nature is the largest source of methane (41%): wetlands, lakes, termites, oceans and permafrost1. Methane from all agricultural activities contributes to only 33% of all methane emissions of the planet. This number includes a large proportion of methane emissions from handling waste and manures. The other portions of global methane emissions are from producing fossil fuels (19%) and from land fires (6%).
- Methane emissions contribute largely to global warming. Not completely correct as the majority of the planet’s yearly methane emissions (98%) are sequestered by the atmosphere and soils1. From this amount, 92% of methane turns into CO2 in the atmosphere.
- Cattle speed up global warming. Not true either. Cattle are naturally recycling carbon from the atmosphere through the plant back in the atmosphere. No new CO2 (or new carbon) is being created. It works like this: grass takes up CO2 from the air and creates sugars (carbohydrates) in its body. The cattle eat grass. Bacteria in their stomach break grasses’ sugar apart (the same carbon that came from the air originally), releasing some of this carbon as methane (CH4). Methane breaks down into CO2 in the atmosphere which the plants use again. So it is the same carbon changing forms. From CO2 in the air -> C in plant -> methane CH4 -> CO2 in the air. This contrasts with “New” carbon that is being released when we are burning fossil fuels. Carbon was stored away in fossil fuels for millions of years keeping CO2 in the atmosphere low as a result. Now that we are releasing these age-old stores, we are adding brand new (or rather millions of years old) carbon into the atmosphere as CO2.
As you can appreciate, the methane story you’ve heard is not as simple as it is portrayed.
Let’s delve into grass fed versus grain fed cattle and which one is the best for the environment.
Grass fed versus grain fed – which is better for the environment?
Which cow do you think will produce more methane? One which eats only grass or one which eats only grain?
The answer lies in the ease with which these food categories can be digested. Grass is harder to digest than grain. There will be more fermentation from bacteria. And more fermentation equals what?
Correct, more methane. On the other hand, grain is easier to digest, so it creates less methane.
But we need to think beyond just comparing methane in different groups of cattle managements. What goes into making a grain fed beef animal?
It is an incredible amount of grain. A single animal needs 1 tonne of barley, 30 kg rapeseed, 23 kg sugar beet and 14 kg soya (AHDB). If we think in terms of fertilizers and pesticides that were needed to produce this grain, it equals to 40 kg of fertilizers and 0.5 l of pesticides (Pesticide usage report 2018).
How many tractor runs did the farmers have to do to grow this grain? Fertilizers were spread in 2 tractor runs and pesticides in 5 tractor runs. Plus ploughing, preparing a seedbed, seeding and harvesting. That is 11 tractor runs altogether.
Now think about keeping that cattle in a barn. You need to prepare their feed. Crack or mill the barley and other grains and mix it with grass silage. Then spread it for the cattle every day. Then, you need to clean their shed regularly, using a tractor again. And once you have a pile of manure, you need to spread it on the fields (using a tractor again).
So a conventional beef adds more new carbon in the atmosphere from burning fossil fuels. Grass fed beef produces more methane but doesn’t use all those fossil fuels so it more than offsets the emission difference. Plus, it can do something more amazing.
Grass fed cattle can reduce global warming.
How can grass fed cattle reduce global warming
Sounds unbelievable? The reason is that cattle can stimulate grasslands to pump CO2 from the air into the soil and store it there for good.
As a soil carbon, it now holds water and prevents floods and droughts.
How does it work? Just as before, the plant takes CO2 from the atmosphere. A grass plant puts 30% of this carbon into its leaves, 30% into its roots and 30-40% it injects into the soil. Plants cannot move around so they have devised a trading system with bacteria. Plant injects carbon (sugars in fact) into its root zone to attract bacteria that will bring it minerals and nutrients for growth. The plant is trading what it can give – carbon-rich sugars – for what it can’t get (minerals) since it is immobile.
Periodic grazing with long rest stimulates the grass to inject more carbon in the soil and keep re-growing more often. Into taller, greener plants. The taller and greener they are, the more CO2 they can harvest via their leaves. The more CO2 can be harvested, the more carbon can be stored in the soil.
This system works only when there is no overgrazing. In peak growing period that means letting cattle graze an area only for 24 hrs since the plants are regrowing so quickly. Why is it important? As soon as the cattle graze plants when they are recovering from just being grazed, they weaken them and break the system of carbon storage in the soil.
Not all 100% grass fed beef systems are equal. Only a few of them work to sequester carbon by moving their animals over grasslands every day.
Those grazing systems that do sequester carbon can inject an incredible amount of CO2 into the soil. Let me give you an example. At a sequestering rate of 2.5 t C/ha/year2, our herd of 150 cattle can sequester whopping 1,404 t CO2 from the air in the soil. That is equivalent to lifestyle emissions of 140 people.
You can follow my calculations for more details:
- 150 cattle running on 550 acres. 550 acres = 222 ha
- Rate of sequestering is 2.5 t of C per ha2, so that is 2.5 x 222 = 555 t C. To put this amount of carbon into an equivalent amount of CO2, we have to multiply by -3.666 (IPCC). 555 x -3.666 = -2,034.63 t CO2 sequestered
- The methane emissions of cattle in CO2 equivalent terms are 12.14 kg CO2/kg of beef3. Our cow deadweight is about 350 kg. So 12.14 x 350 = 4.2 t CO2 per cow. We have 150 cattle, so that is 4.2 x 150 = +630 t CO2.
- When we take away cattle’s emissions from our sequestering rate, we conclude 2,034.63 – 630 = -1,404.63 t CO2/year
This means that a beef cow from such herd sequesters -9.3 t CO2 every year. This is equivalent to yearly emissions of your lifestyle (+10 t CO2/year).
Now you can see how such a way of keeping cattle can become the solution for our future.
No more guilt from eating beef
You understand that the methane story is not as simple as media have you believe. And that by choosing 100% grass fed beef you are not doing any harm to the planet. You are just cycling the same carbon without releasing a new one as is the case of conventional beef.
And if you seek to buy beef from cattle that are managed in a way that sequesters CO2 from the atmosphere in the soil – you are completely offsetting your carbon emissions. Without buying an electric car.
Eat beef and enjoy.
- 1.Saunois M, Stavert AR, Poulter B, et al. The Global Methane Budget 2000&#8211;2017. August 2019. doi:10.5194/essd-2019-128
- 2.Teague WR. FORAGES AND PASTURES SYMPOSIUM: COVER CROPS IN LIVESTOCK PRODUCTION: WHOLE-SYSTEM APPROACH: Managing grazing to restore soil health and farm livelihoods1. Journal of Animal Science. February 2018:1519-1530. doi:10.1093/jas/skx060
- 3.Audsley E. An assessment of greenhouse gas emissions from the UK food system and the scope for reduction by 2050: how low can we go. Godalming, UK: WWF UK and Food Climate Research Network. 2010.