But what is forgotten is that cattle farming can be climate-positive if it is done right (regenerative grazing) and if we really look at its impact in its full complexity.
One of the main reasons given against beef consumption is methane production. Cattle farming is rightfully associated with it for two reasons.
However, appropriate husbandry, specifically regenerative grazing, can significantly affect the impacts of both of these.
Regenerative grazing mimics the natural movement of herds on pastures. It has a positive impact on carbon sequestration in the soil and natural principles can cope with the methane excreted by the cows' digestive systems. Manure accumulation is even eliminated completely in regenerative grazing.
If we look back in history, we see herds of large herbivores such as bison, elephants, reindeer, buffalo, and even earlier, mammoth, grazing on the grasslands.
All of these herbivores produced large amounts of methane when their digestive tracts anaerobically decomposed cellulose. This amount of methane was not significantly different from the amount of methane that comes from cattle farming today.
In a study in 2012 scientists estimated the biomass of large mammals on Earth during the last ice age at about 1.4 billion tonnes. And, as the Czech scientists report in an article in the journal Vesmir, that's more than the sum of today's human (0.4 billion tonnes) and livestock (0.8 billion tonnes) biomass.
In another study, they compared the methane production of wild buffalo and other herbivores before Europeans arrived in the Americas. They found that methane production then was equivalent to 86% of today's methane production from livestock in the US. Large amounts of methane were produced by the digestive tracts of herbivores long before climate change.
So the problem is not the methane itself, but the environment in which it is produced. The difference between prehistoric natural grazing and today's factory farming is huge. Natural mechanisms can eliminate the negative effect of methane from cellulose digestion. There are two basic natural principles. Either methane can be broken down by chemical reactions in the atmosphere or it can be broken down by soil bacteria.
An example of rotational grazing, which is a useful tool for mimicking the grazing by herds of large herbivores in the past.
A crucial role in the lower atmosphere is played by the hydroxyl radical (OH), which can split methane (CH4) into the methyl radical (CH3) and water (H2O). Further oxidation reactions then result in the conversion of the original methane into the much less harmful carbon dioxide (CO2) and hydrogen (H).
Nobel Prize winner Paul Crutzen coined the term "atmospheric scavenger“ for OH to describe this important scavenging role of OH. The hydroxyl radical is a highly reactive gas with a lifetime of only one second, and its abundance is highly variable in time and place. It is formed by the action of solar UV radiation on ozone in the presence of water vapor. The highest concentrations of OH are found over tropical areas where there is the most sunlight and water vapor.
Historically, the amount of light does not change, but the amount of water vapor does, because the small water cycle is significantly disturbed in man-managed industrial landscapes. The purpose of regenerative grazing is then to regenerate diverse vegetation and promote water absorption in the soil, thereby increasing the capacity and activity of the small water cycle, where plants transpire water vapor which then condenses into rain.
Methanotrophs, bacteria that decompose methane, live in healthy soil. It is their only source of carbon and energy. As a 2018 Polish study showed, the activity of bacteria Methanotrophs in soil with not-till management is 2 to 4 times higher than in cultivated soil.
The highest activity of methane-decomposing bacteria is in healthy soils with a high ratio of moisture and organic matter. Such conditions occur on pastures with lush vegetation, which is also supported by regenerative grazing. It cannot be achieved by continuous grazing of a large area, which often results in overgrazed vegetation. These pastures have a lower proportion of moisture and organic matter.
The Global Methane Budget 2008-2017 provides estimates of methane emissions and decay by source. It indicates that soil breaks down only about 5% of the volume that decomposes in the atmosphere. The future threat is the decreasing potential for methane to decay in the atmosphere due to lower ground moisture and collapsing small water cycles.
Source: Global Carbon Project 2020. Most methane emissions are eliminated in the atmosphere and soil. This will cover naturally occurring methane emissions. However, it is not enough to offset emissions from human activities.
Today, total methane emissions are higher overall than what can decompose in the atmosphere and soil. This is due to emissions from fossil fuel extraction and use, agriculture and landfilling.
The amount of methane emitted directly from cattle farming depends on the method of farming and the type of feed. According to a 2006 IPCC study, emissions from the digestive tract of cattle range from 55-99 CH4 kg/year per livestock unit (LSU) and emissions from manure are 6-11 CH4 kg/LSU/year.
For outdoor grazing, methane emissions from manure are zero because no manure pile is formed and therefore anaerobic decomposition of the feces doesn't occur. The cow manure decomposes in the presence of air, and its decomposition on the land also enriches life both above and in the soil.
A positive effect of regenerative grazing on methane decay in the soil and especially in the atmosphere probably exists, but is very difficult to quantify, so there are no scientific studies on this. However, there are already studies that demonstrate the positive effect of regenerative grazing on the capture of CO2 from the atmosphere and its deposition in the soil as organic matter.
This carbon sequestration process uses the principles of photosynthesis and the symbiosis between plants and soil microbiology. Carbon dioxide is converted by plants into carbon-based sugars during photosynthesis. Plants use most of it for their own construction and transport about 40% through the its roots to bacteria and fungi in the soil, which in return make nutrients available to the plant. This promotes the growth of organic matter, which stores carbon in the soil. This process only works properly and intensively in healthy pastures with a variety of grasses that have deep roots.
In a 2018 study, scientists calculated that through carbon sequestration, regenerative grazing can offset the negative impacts of methane emissions. The researchers estimated the annual sequestration value at 3.6 tonnes of carbon per hectare, or 13 t CO2/ha/year.
In this study, the researchers compared the greenhouse gas emissions of conventionally reared cattle with those of regenerative grazing. Per kilogram of slaughter weight, emissions were lower in the conventional (FL) system because cattle grow faster and to a higher weight under these conditions. However, once they factored in the carbon sequestration value of regenerative grazing (AMP), they came up with a negative value for the emissions.
The carbon footprint per kg of deadweight is 6.12 kg CO2eq for conventional grazing, whereas for regenerative grazing it comes out to a negative value of -6.65 kg CO2eq. Beef from regenerative grazing is thus climate positive and its consumption contributes to combating the cause and effects of climate change.
Source: https://www.sciencedirect.com/science/article/pii/S0308521X17310338
Conventional livestock farming is prevalent in the world and in Europe and is a major burden on the planet. Therefore, recommendations to limit beef consumption to reduce our personal carbon footprint are reasonable. Projects are developing to produce various beef substitutes with a lower carbon footprint.
But none of them are carbon negative like beef from regenerative grazing. In addition to carbon sequestration, this method of farming has many other benefits that plant-based meat does not provide. It contributes to a better ability to retain water in the landscape and an increase in biodiversity in the landscape. There are more insects, birds and other species of flora and fauna on healthy pastures.
In the Carboneg project, we therefore support farmers to switch to regenerative grazing. Next time we will bring you the story of two Czech farmers who discovered this method by themselves years ago and are pioneering it in the Czech Republic.
