Do beef farmed pastures net remove carbon emissions?

Question

This viral image claims that an example beef farm with 130 cattle removes many tons of Carbon from the atmosphere every year. However it does not provide any sources.

This image has been shared many times - e.g. [1], [2], [3], [4] - some of these date back to July 2016.

Is anything in this info-graphic factual? Do the pastures required for cattle farming reduce the amount of carbon emitted to the point where it is a net reduction of carbon?

Answer 1

No.

This is not really an infographic that is truthful. It is 'anecdotal evidence' evidence for one farm, very probably not true for that very farm, and in any case a misleading oversimplification.

Pasture land can sequester some carbon, yes, but how meaningful is that? Carbon is just the element, and the element is not a greenhouse gas (GHG). Carbon dioxide is a GHG, and yes, green pastures do capture some CO₂. But even if true that 112 tons of carbon gas is emitted and 500 tons sequestered annually, what does that translate to in practice if 500 tons of CO₂ are captured but 112 tons of methane released?

For global warming climate change that would be a huge problem as methane is much more warming than CO₂. Up to 34 times worse over a 100 year period. It also leaves out other gasses like N₂O that are also a bigger problem than CO₂. With that line of reasoning one could also argue that killing and eating a cow stops it from producing methane and thus the animal meat eaten by humans is saving the planet!

However, emissions from livestock respiration are part of a rapidly cycling biological system, where the plant matter consumed was itself created through the conversion of atmospheric CO2 into organic compounds.

Since the emitted and absorbed quantities are considered to be equivalent, livestock respiration is not considered to be a net source under the Kyoto Protocol. Indeed, since part of the carbon consumed is stored in the live tissue of the growing animal, a growing global herd could even be considered a carbon sink. The standing stock livestock biomass increased significantly over the last decades (from about 428 million tonnes in 1961 to around 699 million tonnes in 2002). This continuing growth (see Chapter 1) could be considered as a carbon sequestration process (roughly estimated at 1 or 2 million tonnes carbon per year). However, this is more than offset by methane emissions which have increased correspondingly.

The equilibrium of the biological cycle is, however, disrupted in the case of overgrazing or bad management of feedcrops. The resulting land degradation is a sign of decreasing re-absorption of atmospheric CO2 by vegetation re-growth. In certain regions the related net CO2 loss may be significant.

Methane released from enteric fermentation may total 86 million tonnes per year. Globally, livestock are the most important source of anthropogenic methane emissions.

In the United States methane from enteric fermentation totalled 5.5 million tonnes in 2002, again overwhelmingly originating from beef and dairy cattle. This was 71 percent of all agricultural emissions and 19 percent of the country’s total emissions (US-EPA, 2004).
_{–– Food and Agriculture Organization of The United Nations: "Livestock's Long Shadow: Environmental Issues And Options", Rome, 2006.}

Of course, the picture alludes to how coal and oil got into the ground in the first place. Plants and animals are carbon based, when they died and were buried deep enough without immediate decomposition/recycling by other lifeforms the were effectively sequestering carbon out of the atmosphere.

The reality looks a bit different for current farming practices. Only careful management in a less than now common in industrialised intensive farming has the potential to be less damaging for the atmosphere. The style and sheer amount of Western capitalist agroculture for cattle raising has to be reduced or changed significantly otherwise, as no farming practice that conforms to current market demands complies with reducing GHG emmissions.

The US Natural Resources Conservation Service currently advises a rule of thumb that 1 cow needs 2 acres to be fed with grass for a year.

The daily utilization rate for livestock. This is always the same number, .04, or 4%. This figure is used because livestock need to have 4% of their weight in forage each day (2.5- 3% intake, .5 trampling loss and .5-1% buffer). (PDF)

With 130 animals on the example from the claim, that farm is already quite crowded and it will damage the pasture if it is not extremely productive and resilient or other fodder than grass is provided into the mix. Since that's left out from the picture, the numbers are already skewed.

This effect isn't really news:

Overgrazing of pasturelands is one of the major problems facing the Oklahoma farmer today. Aside from soil erosion on cultivated land, excessive pasturing of prairie and woodland is perhaps our greatest agricultural menace. Greater runoff from grazing land as the vegetation is destroyed added to water lost from tilled soil has increased the flood problem not only in Oklahoma but throughout the country.
_{–– Charles Clinton Smith: "The Effect of Overgrazing and Erosion Upon the Biota of the Mixed-Grass Prairie of Oklahoma", Ecology, Vol. 21, No. 3 (Jul., 1940), pp. 381-397.}

The USDA has calculated the effect of reconversion from crop fields to grasslands in the most optimal conditions on highly productive land in the North-Eastern US. These calculations should indicate that the numbers used in the claim are most probable what on Skeptics constitutes original research' that unfortunately erred along the way:

Decades of plowing have depleted organic C stocks in many agricultural soils. Conversion of plowed fields to pasture has the potential to reverse this process, recapturing organic matter that was lost under more intensive cropping systems. Temperate pastures in the northeast USA are highly productive and could act as significant C sinks. However, such pastures have relatively high biomass removal as hay or through consumption by grazing animals. In addition, the ability to sequester C decreases over time as previously depleted stocks are replenished and the soil returns to equilibrium conditions. The objective of this research was to use eddy covariance systems to quantify CO2 fluxes over two fields in central Pennsylvania that had been managed as pastures for at least 35 yr. Net ecosystem exchange measurements averaged over 8 site-years suggested that the pastures were acting as small net C sinks of 19 g C m⁻² yr⁻¹ (positive values indicate uptake). However, when biomass removal and manure deposition were included to calculate net biome productivity, the pastures were a net source of −81 g C m−2 yr−1 (negative values indicate loss to the atmosphere). Manure generated from the hay that was consumed off site averaged 18 g C m⁻² yr⁻¹. Returning that manure to the pastures would have only partially replenished the lost C, and the pastures would have remained net C sources. Heavy use of the biomass produced on these mature pastures prevented them from acting as C sinks.
_{–– R. Howard Skinner (USDA-ARS): "High Biomass Removal Limits Carbon Sequestration Potential of Mature Temperate Pastures", Journal of Environmental Quality, July 2008.}

And even in scientific studies arguing for re-calculating the CO2-sink effect of grasslands has to admit:

Grazing pressure is a factor that affects C sequestration although it was not included in this study. … This question does not have a simple answer if we consider that our study was focused on a regional scale. It is clear that C losses may be high in grazing areas of high cattle density. Intensive and frequent grazing imposes an increased C removal from roots to allow subsequent vegetation regrowth. For example, a meta-analysis investigation (Zhou et al., 2017) that comprised 115 cases suggests an additional carbon loss due to intensive grazing of about 21%. Very high stocking rates (N4–5 heads/ha) explain such losses. …
Although animal densities were heterogeneously distributed […] in this study we assumed that those densities were low enough to prevent any significant loss of belowground C. So, we desisted from applying any uncertain coefficient to account for carbon losses due to grazing intensity. …
Change of C stock due to land conversion was not specifically consid- ered in this research methods, but some aspects deserve a comment. There is meaningful question that has not still been completely an- swered. Do forests always sequester more C than grasslands as IPCC guidelines assumed? In a global meta-analysis that involved 385 studies on land-use change in the tropics Don et al. (2010) tend to confirm this assumption.
They showed that the highest SOC losses were caused by conversion of primary forest into cropland (−25%) and perennial crops (−30%), and forest conversion into grassland also reduced SOC stocks by 12%. …
Although management practices were not analyzed in this study, in line with scientific evidence (Conant et al., 2017) we also believe that management is a factor that can significantly improve carbon sequestra- tion. But provided that our knowledge about how grazing lands are managed in different sites of world is limited, we have to accept that figures on C sequestration due to management interventions remain uncertain (Smith et al., 2007).
_{–– E.F. Viglizzo et al.: "Reassessing the role of grazing lands in carbon-balance estimations: Meta-analysis and review", Science of the Total Environment, 661 (2019) 531–542.}

Cattle raising currently and globally emits much more than it captures in the long run. Only grass fed beef can be sustainable in the sense of 'less damaging'; and only on suitable land that is not forested now. As soon as you feed grains to cattle in mass the calculation fails. And the optimistic calculation from the claim only could work if the pasture would be growing topsoil with carbon incorporated into it in more stable forms. When organic matter recycling, or erosion and other forms of topsoil loss enter the picture, again, the calculation fails.

Cattle dominate livestock related emissions, contributing around 65% of the total, buffaloes and small ruminants add a further 9% and 7% respectively, so in all ruminants account for over 80% of total livestock related climate impacts, most significantly via enteric methane (Figure 3) – which are highest, per unit of milk or meat, in grazing systems. Other studies give broadly comparable estimates. This 80% share of GHG emissions is worth setting against the 50% that ruminants contribute to overall terrestrial animal product protein supply (Figure 3). Grazing systems specifically emit an estimated 1.32 Gt CO2-eq (a figure that includes land use change-related impacts), which is about 20% of all emissions from livestock.

• Soils are very significant carbon stores. All soils contain carbon although different soil types differ in how much they contain. Above ground biomass also stores carbon – especially trees.
• As plants grow they draw down carbon from the atmosphere, apportioning some into their roots. Much of this is released back to the atmosphere when plants die and decompose. But, if left undisturbed, some of the carbon in their roots and in plant litter – depending on climate, rainfall, the soil microbial community, management and many other variables – may eventually be incorporated into more stable compounds in the soil, constituting a net removal of carbon from the atmosphere. This is soil carbon sequestration.
• If favourable conditions continue, soils sequester carbon until equilibrium is reached, after which emissions and removals are balanced and no more is sequestered. Further increases in sequestration may be possible if there is a change in how the land is used or managed.
• Sufficient nitrogen needs to be available for plants to grow and therefore for soils to sequester carbon. This can be provided in the form of bacterial nitrogen fixation, such as that associated with the roots of legumes, application of mineral fertilisers or organic amendments containing nitrogen, but higher nitrous oxide emissions may outweigh sequestration gains.
• Since sequestration is time-limited, so too is its role in mitigation efforts. There are additional problems of reversibility (what can be done can be undone) and leakage (organic amendments applied on one area of land may be at the cost of its previous application elsewhere). Legacy effects of past management practices also need recognising to avoid drawing false conclusions about the effects of the current management regime.
• Grazing animals potentially aid the process of sequestration as their consumption of herbage stimulates plant growth and leads to the partitioning of and increase in organic matter below ground.
• Factors including soil type and quality, climate and seasonal variability, precipition levels, nutrient availability, composition of soil fauna and microbial communities, and vegetation type will influence whether organic matter is converted into stable below ground carbon which determines if sequestration actually occurs.
• In many parts of the world the potential for grazing management to achieve sequestration is limited or absent.
• Heavy grazing is a problem on many grazing lands: by reducing plant growth, it causes carbon losses from the system.
• Evidence as to the sequestration benefits of holistic, adaptive and other variants of rotational grazing is patchy and highly contradictory. Where there are benefits, these are small.
• The highly ambitious claims made about the potential for holistic grazing to mitigate climate change are wrong.
• The sequestration potential from grazing management is between 295–800 Mt CO2-eq/year: this offsets only 20-60% of annual average emissions from the grazing ruminant sector, and makes a negligible dent on overall livestock emissions.
• Expansion or intensification in the grazing sector as an approach to sequestering more carbon would lead to substantial increases in methane, nitrous oxide and land use change-induced CO2 emissions…
• Practices that are optimal for achieving soil carbon sequestration may not be so for other environmental goals, such as biodiversity conservation.
• Leaving aside any scope for sequestration it is imperative that we ‘keep carbon in the ground’: by acting to halt degradation or conversion to croplands to avoid losing the huge carbon stocks already stored in grasslands.

_{–– Tara Garnett, Cécile Godde et al.: "Grazed and confused? – Ruminating on cattle, grazing systems, methane, nitrous oxide, the soil carbon sequestration question – and what it all means for greenhouse gas emissions", Food Climate Research Network, Oxford Martin Programme on the Future of Food Environmental Change Institute, University of Oxford, 2017. (PDF)}

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As the above might read 'a bit too anti-beef': It might be noteworthy to emphasise the last point from the last quote: cattle production as such is not the devil, and that for ensuring human nutrition converting grassland to intensive agriculture annual crops with tilled bare soil and ample fertiliser and pesticide usage is actually worse, carbon-wise, as it contributes a massive carbon loss in the soil organic matter under ideal conditions and facilitates erosion and thus total top-soil loss and huge carbon emissions. Just planting maize monocultures instead of raising cattle doesn't solve anything.

The conversion of grasslands to arable use has led to a 25–43% decline in soil carbon stocks in the uppermost 120 cm in the USA, as compared to native grassland (Potter et al. 2000). A well documented chronosequence in France has yielded similar results (Boiffin & Fleury 1974). The mean carbon change induced each year by converting a permanent grassland to an annual crop can reach -0.95 T ± 0.3 t C ha^-1 yr ^-1 over a 20-year period.
_{–– J.-F. Soussana et al: "Carbon cycling and sequestration opportunities in temperate grasslands", Soil Use and Management (2004) 20, 219–230. DOI: 10.1079/SUM2003234 (PDF)}

Answer 2

Here's something nobody ever seems to ask: What's the alternative? Surely we aren't picturing a pastureland that would have been paved over with asphalt, if not for this heroic rancher? Certainly in a "natural" state, something would be growing there, and of course that would mean something else would be there eating it.

Without human intervention, most pastureland on the Great American Prairie would still be growing grasses. Prior to the industrial age, this prairie was covered with hundreds of millions of large herbivorous mammals, topped by the American Bison (which is a Bovine closely related to domestic cattle). Individual herds of Bison used to be more than a million strong. These were effectively roving cities of the creatures. The following map shows their historical range during the Holoscene (darker for more recent species).

What this means is if you are interested in the earth's carbon throughput compared to what it would naturally have been prior to human activity, cattle and their pastures are kind of a wash. It really doesn't make much sense to include them in your numbers, unless you are attempting to make them look artificially better or worse by taking credit for something that was already going on before humans ever got here.

Answer 3

Some of it is close to factual data for one particular farm in Nova Scotia.

The infographic was based on calculations from this Wild Mountain Farm. The calculations were made with a calculator that is no longer available (or I couldn't find one that is called CPLAN). But using data from Carbon Footprint of Beef Cattle (the values are pretty similar in various researches) and estimated weight of 50 cows and 80 calves, even taking the lower values we end up with 154 tones.

The "Source" page also state that they produce "around" 29 tones of carbon from equipment (truck, tractors coolers). But they statements are prefixed with "About, around"

The thing is that for that particular farm the amount of acres is actually 300 not 150. They state they have 300 acres of which 150 is used for hayland and second part for grassland. And the result, of 554, is based on those 300 acres. Someone who made the infographic "tweaked" data a little to have better visual outcome.

Answer 4

First, it's important to mention that not all carbon is created equal. That is, some greenhouse gases are much worse than others. But in the interest of the claim, let's look at carbon, only.^*

With that out of the way, we should also specify what a meaningful definition of "carbon emission" is. The infographic directly equates emissions from cattle, tractors with the carbon captured by grasslands. However, aside from grazing, there are many other ways that grasslands will release carbon back to the atmosphere.

Instead, let's look at how farming affects long-term storage. The picture becomes much simpler in a way: we simply want to compare the amount of carbon emitted from permanent storage (in other words, fossil fuels) with the amount of carbon sequestration by the grasslands.

According to [1], the amount of carbon sequestered by grasslands worldwide is 0.5 Pg/y, over a total area of 35 million km². Of that area, 20 million km² is used for livestock. Let's be optimistic and say that only fields used for livestock sequester carbon. That means that in total, our 150 acres sequester 15.2 tons of carbon, annually. If we take the 32 tons emitted by transport and processing at face value, this means that the net longterm emissions are a little under 17 tons of carbon annually.

Note that the 500 tons claimed per acre would be approximately equivalent to the amount of carbon captured by grasslands, if all the grasslands worldwide were in tropical regions

[G]ross primary production (GPP) is the major natural soil C input and has been estimated at 31.3 Pg C yr−1 for tropical savannas and grasslands

However,

The net primary production (NPP) of grassland denotes C assimilation by plants before losses caused by grazing, harvest, herbivory, mowing, and other processes. However, the numerous processes of NPP loss are among the reasons why direct measurements of NPP of grassland are challenging because not all of the biomass produced remains within the ecosystem.

[1] Lorenz K., Lal R. (2018) Carbon Sequestration in Grassland Soils. In: Carbon Sequestration in Agricultural Ecosystems. Springer, Cham. https://link.springer.com/chapter/10.1007/978-3-319-92318-5_4

^{* Keep in mind that, effectively, cows convert atmospheric CO2 to atmospheric methane via a roundabout process which involves eating grass a lot.}

Answer 5

The way the answer is put no, not at all.

There are lots of metrics above so I won't repeat anything. But I will state the obvious:

The pasture land will sequester carbon regardless of the operation of the farm. It is not a mandatory part of the farm cycle from this perspective.

So the farm itself has a carbon emission cost and carbon sequester from the pasture cannot be subtracted.

However it is not possible to determinate the potential for carbon sequestration compared used an unused pasture. In overall more research is needed as various sources indicate:

• The Potential for Carbon Sequestration Through Reforestation of Abandoned Tropical Agricultural and Pasture Lands
• Organic Carbon Turnover in Three Tropical Soils under Pasture after Deforestation
• Agroforestry for biomass production and carbon sequestration: an overview
• Sustainability of pasture-based livestock farming systems in the European Mediterranean context: Synergies and trade-offs

This source however has a lot of research metrics that display natural grasslands as at least equal to farm pastures in many cases: Soil Organic Matter Turnover in Long-term Field Experiments as Revealed by Carbon13 Natural Abundance

Concluding that a farm, probably, does not increase the potential for carbon sequestration at an amount sufficient to counter farm's carbon emissions.

If you have more time there is an analytical source here:

Ecological complexity: intensifying land use has generally brought with it a simplification and reduction of biodiversity. Amongst the causes and disturbances are deforestation, fragmentation of ecosystems, regulation of water streams, monocultures, selective breeding, abandoning traditional crop varieties and livestock breeds, intensive application of agrochemicals, etc.

Source: Soil Organic Matter Turnover in Long-term Field Experiments as Revealed by Carbon13 Natural Abundance

Answer 6

3 things to keep in mind.

1. Global trends in agriculture are NOT always valid in all regions of the globe. For example it is factually incorrect to extrapolate the global trend <that conversion to pasture is the #1 cause of deforestation> to North America where it is virtually non-existant as a meaningful cause of emissions due to land use change. The largest cause of deforestation in Canada is actually timber harvesting which causes 44x more GHG emissions compared to all agricultural land use changes.

2. According to the IPCC recommended practices for national GHG inventory reporting (2003), biogenic Sequestration is to be treated as a carbon removal and netted against anthropogenic emissions on Managed Lands in accordance with national designations. In both Canada and the USA, all agricultural land is desginated as Managed Lands. So sequestration from pasture grass is permitted to be netted against livestock emissions, even if the pasture grassland preexisted the farm.

3. Beef cattle cannot manufacture carbon from subatomic particles. They can only chemically transform the organic carbon from the foods that they eat into CO₂ and CH₄ (methane). That means that they cannot produce more carbon output than they chew up in their food.

It also means that even accounting for a 25x higher GWP100 weight for CH₄ as a Green House Gas (GHG), unless they eat all the grass in the pasture (which only happens in severe over crowding and rarely occurs in practice because the cattle would run out of food, something that farmers would prevent), it is not possible for emissions to outweigh sequestration.

The Lanigan Group is a Canandian consultancy, specialising in net-zero agriculture. In their presentation, Enteric Emissions are Carbon Neutral that documents the fate of carbon on a 1300 acre dairy farm. It shows that even using 25x for CH₄ and 298x for N₂O, total livestock emissions do not exceed carbon sequestered in the crops eaten.

Our analysis, presented [later in document], shows that enteric emissions are significantly better than net-zero such that livestock production is best understood as part of a process for carbon capture & storage