Is livestock destroying the planet?
We've all heard, seen or read the media hype. Livestock are major contributors to climate change, through their direct emissions and the indirect emissions of the industry producing them. The magazine article 'Livestock and Climate Change' is typical of the misinformed and pseudoscientific claim that grazing herbivores, particularly ruminants, are contributing to a serious environmental disaster.
The result has been a widespread misinformation campaign by government agencies, the UN and NGOs about human diet and health, many claiming that humans need to cut their consumption of meats and increase reliance on 'plant based proteins' as part of a 'plant based diet'. The following BBC article sums up this propaganda campaign:
There are some scientific authors countering this narrative, but they're not as widely covered by the media, because there's little ideological drive to push this counter-argument. If one googles the subject including 'National Post', you'll find the 'cattle are bad' articles vastly outnumber the 'cattle are good' articles. Thankfully, hints at the scientific reality can be found, as this article demonstrates:
So, what is the reality? Well, here's a brief summary.
Are cows a major contributor of greenhouse gasses? A relatively recent claim by some activists is that livestock (and wildlife) emit large quantities of greenhouse gasses and, therefore, are contributing to climate change. The average beef cow emits 100kg of CH4 (methane) each year (mostly through belching, with a small amount coming from the cow’s manure), the equivalent of 2300kg of CO2.
However . . . This claim refers to conventional livestock production, not properly managed livestock production. Herding ruminant herbivores created the great grasslands of the world starting in the Miocene Epoch, creating the deepest and richest topsoil on earth. When wild cattle, wildebeest, impala, bison, etc. live in vast nomadic herds pressured by pack hunting predators and the need to constantly move to find fresh forage, they stimulate enormous photosynthetic storage of atmospheric carbon in the form of soil organic matter.
In conventional livestock management, we replace huge constantly moving nomadic herds tightly bunched in relatively small areas for predator protection with small sedentary herds remaining stationary on relatively large areas, the opposite of their behaviour in the wild. The anti-livestock activists blame livestock for the results of human mismanagement. The animals didn’t choose to change their behaviour, we humans forced them to.
‘Properly Managed Livestock’, on the other hand, are managed to mimic the dense herds and nomadic lifestyle of the wild. The results from proper management are amazing and worth considering.
A beef cow eats about 2.5% of her body weight in dry matter forage (the grass/legumes/etc. minus the water content) each day. That 1200lb beef cow is eating 30lbs of dry forage per day, every day. That’s 10,950lbs or 4966kg of dry matter each year. As a grass plant is 50% carbon, that means the cow is eating 2483kg of pure carbon each year. Only 20% of that is turned into energy and cow, so 80% goes back onto the land as manure. Manure is just pre-composted biomass, with many nutrients produced by rumen microbiology that would be absent in compost. What would take up to 2 years in a composting system is produced in a bit over 70 hours by a cow’s digestive system. In addition, the urine of animals is the main source of phosphorus, one of the three soil macro-nutrients, required for healthy plant growth.
In a healthy, properly managed pasture, with good active soil biology, the manure is broken down and sequestered in the topsoil within 6 weeks. By contrast, it would take years of chemical oxidation for the same manure to volatilise and release the carbon back into the atmosphere, so it’s clear that most of it ends up in the soil. For argument’s sake, let’s assume only 50% ends up in the soil, that’s 993kg of carbon (the equivalent of 3.64 tonnes of CO2) being sequestered just from the cow’s manure.
But that’s not the end of the story; In a properly managed grassland pasture, only about 1/3 of the total biomass production is consumed by the livestock, another 1/3 is trampled onto the soil surface with the final third providing leaf area for regrowth. As animals do not graze evenly, this is just and average, with some areas being more grazed/trampled and others less. Regardless, this then leaves another 1/3 of the above grownd biomass to biologically decay and be deposited in the topsoil. If only 50% ends up in the soil (a gross underestimation), then that’s still another 1243kg of carbon stored in the soil, or 4.56 tonnes of CO2.
This trampling and grazing put the plants back into stage 1 or 2 growth, resulting in the absorption of sunlight and CO2. If the grass isn’t grazed, it enters senescence, produces seed and goes dormant, at which point photosynthesis shuts down and it stops absorbing carbon.
Every 30-45 days or so in central Alberta, the plants can complete the cycle and be exposed to the grazing herbivore for a short period. Exposure to grazing herbivores allows many grasslands to complete 2-4 complete growth cycles in each summer growing season, instead of the single cycle it would complete if left ungrazed.
So, we now have 2236kg of carbon being sequestered in topsoil each year by the cow. If we consider the atomic weight of carbon is 12, and the atomic weight of oxygen is 16, that means that 8.2 tonnes of CO2 has been sequestered in grassland topsoil by the cow, each year.
Again, that’s not the whole story. The leafy portion of a healthy grass plant is only 10-25% of the biomass of the plant, depending on species and growing conditions. The root system contains 75-90% of the carbon in the plant and, each time it is grazed it releases a mass of root exudates (carbon in the form of plant sugars) to attract soil biology with nutrients for the plant. The plant trades carbon (food for the microbes) for nutrients it needs to regrow. When the soil biology dies and releases nutrients to the plant, the carbon in the soil biology becomes soil organic matter, sequestered carbon.
So, a 1200lb beef cow has the potential to store over 8.2 tonnes of CO2 in topsoil every year through her direct surface action plus additional carbon stored by stimulating plants to pump carbon into the soil. She only emits the equivalent of 2.3 tonnes while doing so. With 52 million acres of farmland in Alberta, that’s a huge carbon sink in a form that benefits the environment and humans alike. The only thing preventing this outcome is human management of grazing.
This effect is so powerful that when smallpox hit, in the 16th century, the native farming populations of what is now the southern US and northern Mexico, around 90% of the population died. Their croplands were abandoned, turned back to grasslands and the bison moved back in. The increase in carbon absorption of this tragic event was so strong that the Greenland ice core data indicates a measurable global reduction in atmospheric CO2, an effect that lasted for over a century.
In the last few weeks (May 1st, 2019) a study was published by Quantis, an international research firm contracted by General Mills and a regenerative farm called White Oak Pastures. In that study, the Life Cycle Assessment (LCA) on beef raised using Holistically Planned Grazing demonstrated net CO2 emissions of -3.5kg of CO2 equivalent per kg of beef produced. This means they stored the equivalent of 3.5kg CO2 in the soil for every kg of beef produced. Compare this with ‘Beyond Burger’ whose own LCA demonstrated a net emission of 4kg of CO2 per kg of product. The beef is a carbon negative and the plant-based meat is carbon positive.
Again . . . you guessed it, even that is not the whole story. In a healthy soil ecosystem with robust levels of organic matter (biologically derived carbons), a healthy population of methanotrophic bacteria and archaea comes alive. While soil type, moisture levels and climatic region all determine when a soil becomes ‘healthy’ as opposed to ‘degraded’, it seems that somewhere above 4% organic matter, combined with robust soil health practices (covered on a separate page ‘Grass & Soil’), the soil carbon levels reach the point where they are able to sustain a broad variety of soil biology, including methanotrophs and a plethora of other microorganisms.
These methane-oxidizing microorganisms absorb CH4, converting it into other compounds, releasing energy for themselves and other microorganisms. In a healthy regenerating soil ecosystem, these methanotrophs consume more methane than the livestock living above them produce. So now we have 10.5 tonnes of CO2 being turned into soil organics in addition to the carbons added by the plant roots.
So, regardless of your opinion about the strength of CO2 as a forcing agent for climate, or the influence of CH4 as a greenhouse gas, the grazing herbivore (beef, bison, sheep, goat, deer, moose or elk) living on healthy soil ecosystems, are not part of the problem but instead are essential for a stable carbon cycle and healthy ecosystem.
BUT . . . most domestic livestock are not fed on perennial pastures, but in confined feeding operations that feed high energy feeds based on arable cropped monocultures. This is true, but a ‘straw man’ argument. As previously mentioned, no domestic or wild herbivore eats grain or pulse-based rations in their natural environment, it’s humans who have forced this unnatural diet on the animals. This is a management issue. If animals are properly managed in their natural environment, perennial grassland ecosystems, then the problem of emissions from industrialised livestock management ceases to exist.
Feeding humans on a carbohydrate rich, monoculture crop-based diet has the same effect as it does when feeding it to animals. Soil degradation and erosion, destruction of wildlife habitat, release of organic carbons into the atmosphere and a plethora of diet-based autoimmune diseases.
If you want to be healthier and help preserve the natural ecosystem, eat more grass-fed meat raised using regenerative rangeland practices. An omnivorous diet high in range fed animal proteins and fats enables us, the producers, to return more land to perennial grassland ecosystems which support both livestock and wildlife, which themselves contribute to restoring soil ecosystems and biodiverse plant ecosystems which provide sustainable food production for both humans and animals. Done right, just Canada’s current beef production could store 20+ billion tonnes of CO2 in topsoil each year.
I'll let Joel Salatin finish up for me: