The cow is (not) a climate killer?!

Some advocates of animal husbandry, for example animal nutrition expert Prof. Wilhelm Windisch, veterinarian Dr. Anita Idel, farmer Sven Lorenz, agricultural lobbyist Prof. Frank Mitloehner and chef Sarah Wiener, repeatedly claim in interviews, lectures, articles, lobby platforms and books: "The cow is not a climate killer." We looked at 16 of the most common claims, subjected them to an intensive fact check, and came to the unequivocal conclusion: "The cow as a farm animal is a climate killer."

While the content of the claims is repetitive, the list of sources is long. Some links to them can be found under references [49-57] in the list of sources at the end of this article.

Methane

Generally, livestock and especially cattle advocates try to downplay the role of methane because it is the most significant greenhouse gas from livestock/cow farming.

1. Claim: Methane is 25 times more harmful than CO2.

What is true: This is only true if the period under consideration is stretched to 100 years. The application of this period is purely exemplary and there is no scientific argument for it according to the IPCC [1]. Due to the short-term nature of the dismantling and the urgency of the problem, a shorter period is more appropriate [2]. According to climate models by Myhre et al. (2013), without taking into account sulphate depletion (indirect forcing) [8], methane is more than 100 times more harmful than CO2 over a period of 12 years and 87 times more harmful over 20 years [3].

2. Claim: Methane only plays a role in the short term, but has no effect in the long term. CO2 is cumulative.

What is true: It is true that methane has a very short-term effect, but it has more than 100 times the effect of CO2 over a 12-year period and 87 times the effect over a 20-year period [3]. The constant emissions from livestock, especially cows, lead to a high pedestal concentration in the atmosphere, without which the climate would permanently cool by about 0.2 °C in just 12 years [2]. Especially because of the short-lived nature, the reduction of methane emissions should be a high priority [12],[40]. It is true that CO2 emissions have a cumulative effect on greenhouse gas concentrations in the atmosphere, but these effects are taken into account via the time-related intergals of the GWP models [48].

3. Claim: Methane from fossil fuels is harmful, but methane from cows is not.

What is true: According to the IPCC , methane from fossil sources has a global warming potential (GWP) of 85 over 20 years, while biogenic methane has a GWP of 84. The minimally higher value for fossil methane is due to the fact that it adds new carbon to the atmosphere and the methane ultimately decomposes into climate-impacting CO2 [59]. However, the remaining amounts of CO2 are very small, so that the two warming potentials are almost equal.

Methane decomposes within 12 years, but methane is constantly emitted by the cows, so that an equally high level remains in the atmosphere with correspondingly high radiation effects [11]. Without cows, methane concentrations would drop drastically and thus the climate would cool down enormously [2].

4. Claim: Methane (CH4) circulates in a cycle and is therefore harmless.

What is true: CH4 does not circulate, only the carbon atom it contains. First, the cow absorbs carbon through the grass. Bacteria in the cow's digestive systems decompose the biomass and synthesize the carbon atom with hydrogen to form CH4, which is released into the atmosphere and broken down into CO2 via complex processes that damage the climate. Then the plants reabsorb the CO2. This process takes only 12 years, but within those 12 years methane is more than 100 times more harmful than if there were only the CO2. The carbon atom is in a cycle, but the conversion of CO2 to CH4 is not neutral at all. In principle, the CO2 of the air is replaced by CH4 via the cow, and this permanently, because the conversion with a constant animal population takes place continuously at the same high level [8].

A simple calculation shows how harmful a cow is for the climate: a cow grazing on pasture requires approx. 6700 m2. A cow emits approx. 100 kg of methane per year. With a GWP (Global Warming Potential) of 87, this corresponds to approx. 8700 kg of CO2 equivalents. A cow therefore causes 1.3 kg CO2eq per square metre per year. However, an unsaturated pasture area sequesters only 0.2 kg of CO2 per square metre and year [9]. Without taking other factors into account, a cow grazing on pasture therefore has a net climate impact of 7370 kg CO2eq per year. Other factors further increase the climate damage caused by cows, such as methane emissions from manure, the carbon opportunity costs of maintaining grassland and the regular exhalation of CO2.

Pasture / Grassland

Cow husbandry advocates attempt to portray the use of cows to maintain grasslands as natural, necessary, and beneficial to climate and biodiversity. Cow grazing is promoted as an alternative-free form of using grasslands.

5. Claim: Grasslands are a successful ecosystem in Germany.

What is true: The grassland in Central Europe is anthropogenic, i.e. artificial, and can only exist if it is constantly grazed and mowed. The natural ecosystem in Germany is the forest. Without intervention, the grassland predominant in Germany turns back into forest within a few years through succession [4].

6. Claim: Grazing via so-called "regenerative grazing" (holistic grazing) increases grass growth including the roots in such a way that there is constant net CO2 sequestration by the soil.

What is true: On new grassland, grazing does lead to a small stimulation of plant growth, especially of the roots, but after just a few years the soil can no longer absorb any more CO2 and the effect tends towards zero. From then on, as much CO2 is released as was previously absorbed. This saturation is reached after 30-70 years, so it should have been reached long ago for pasture land in Germany [5]. Another meta-study over 25,000 primary studies comes to the conclusion that grazing even decreases soil organic carbon (SOC) by between 4% and 31% (on average: 7%) compared to non-grazing [60].

7. Claim: Grassland soils store more carbon than forests.

What is true:  Although grassland soils store more carbon than forest soils, forests store an enormous amount more carbon above ground via trees and shrubs. In total, forests store significantly more carbon than grasslands [13]. Forests have a much higher sequestration potential, especially if they have to grow first (e.g., if grasslands are afforested), since they then reach the saturation level only after 100 - 200 years. The sequestration rate of a growing forest is 7 - 21 tons of CO2 per year per hectare [14]. Unsaturated grassland can only bind 2 tonnes net per year and hectare in the soil [9].

8. Claim: Cows contribute to biodiversity.

What is true: Pasture land in Germany offers higher biodiversity than arable land, but the natural ecosystems in Germany, namely forests, have the highest biodiversity. These offer far more and much more diverse habitats. Besides trees, numerous plants, fungi, microorganisms, insects and vertebrates live there [17],[18]. According to a global meta-analysis across 107 studies, grazing in grasslands significantly reduces both the amount of plants and animals and the biodiversity among animals compared to non-grazing. In particular, the quantity and diversity of pollinators decreases [58]. 

If one still wants to keep some grassland, a few animals could be settled e.g. on alpine pastures or in a closed habitat, where they can live there until their natural death and without exploitation (meat, milk). An animal "use" is not necessary in any case.

9. Claim: Grasslands can be used beneficially only by ruminants.

What is true: It is true that feeding grass to ruminants could increase food production, because there is no food competition for this agricultural land and it is ecologically not practical to plow up the grassland. However, additional food production via grasslands is not even necessary in a purely plant-based food system, because existing forage acres are more than sufficient to adequately feed all humans [6]. From the current perspective of climate, biodiversity, and (geopolitical) energy crises, much more sensible uses for grasslands are reforestation, renewable energy plants (solar, wind), nature reserves, and biogas plants based on grass substrates that provide fertilizer in addition to energy [7],[39]. There should be additional government incentives for this, e.g., incentives for investment, CO2 certificates, or direct subsides.

Cows as suppliers of fertilizer / nutrient cycle

Livestock and cow husbandry advocates try to portray animal farming as a necessary and alternative-free component of agriculture.

10. Claim: We need the cows for fertilizer. Cows are necessary for a circular economy.

What is true: In cows, digestion is largely carried out by anaerobic bacteria, which ultimately convert the plant components into manure and methane, among other things. It makes much more sense to let aerobic bacteria take over the conversion of the plants into fertilizer outside of animals, because then the extremely climate-damaging methane is not produced. These innovative techniques are used, for example, in green manuring, composting and the build-up of humus. Legumes can be used as a substitute for artificial nitrogen fertilizers, which can then either be harvested or used as green manure, cut & carry - component or for composting and for building humus [15]. In addition, it is possible to produce fertilizer via grass substrate-based biogas plants using the resulting methane as a renewable energy source [39]. [15]. In addition, there is the possibility of producing fertilizer via grass substrate-based biogas plants and using the resulting methane as a renewable energy source [39].

Quite generally, "farm animals" are not necessary for agricultural cycles. Rather, animal husbandry is an artificial and resource-intensive factor that unbalances material flows. For example, only a part of the nutrients from the animal carcasses is returned to the field, foreign soils are exploited by feed imports and local soils are flooded with nutrients, the high demand for feed requires intensive agriculture using artificial fertilizers and pesticides, and the artificial construct of animal husbandry results in masses of antibiotics entering the fields [16].

Efficiency

Animal agriculture advocates try to portray alternatives to animal agriculture as unfeasible and inefficient.

11. Claim: For one unit of directly edible plant components, four more non-edible plant components are produced. We need cows to turn these non-edible plant components into food. Cows can produce one unit of edible food from the four units of non-edible plant components.

What is true: The ratio shown is not correct. Many plant components can also serve directly as food for humans, and for all others there are efficient, alternative uses.

In the presented ratio of four shares of non-edible biomass for one edible share, Prof. Windisch has included grass to a large extent [25]. However, grass is not a by-product of crops grown for humans. It must therefore not be integrated into this calculation at all.

Furthermore, intertillage of the crop rotation were included [25]Furthermore, intertillage in the crop rotation were included [25]. However, there is no need to feed these to animals. Depending on the species, they can also be eaten by humans (e.g. lupin, legumes). In addition, in bio-cyclic vegan farming, intertillage, by being mulched and plowed under, serve the important purpose of green manuring [26],[27].

Of course, it is true that when crops are harvested, there are components that are not edible for humans. In the example of cereals, the ratio of grain to straw and chaff is 1:0.9, with straw clearly outweighing chaff. However, due to its low nutritional value, the straw is hardly used as animal feed. Only the chaff can be usefully fed to animals, but there are other possible uses. On the one hand, processes are being developed to use them for plant-based meat via fermentation [28][31], and on the other hand, they can contribute to fertilization [27]. The same applies to the non-edible components of all other crops.

Prof. Windisch's calculation also includes by-products of processing [25]Prof. Windisch's calculation also includes by-products of processing [25]. These are primarily rapeseed and soybean extraction meal, spent grains and pomace. These are the protein-rich residues from vegetable oil extraction and beer brewing, and from the pressing residues of fruits and vegetables. All these by-products have long been used directly for human food, e.g. as meat substitutes, for protein powders, for bread, for spirits and for pectin. Recently, however, extraction meals and spent grains can also be used for the production of protein-rich, plant-based meat via new processes [32],[33],[29]. [32],[33],[29].

In the future, there will also be processes and technologies to convert non-edible biomass into high-quality food for humans in the most efficient way possible. For example, companies have succeeded in extracting Rubisco, the most abundant protein on earth, from plants [30]. There will also be processes for converting biomass into all conceivable proteins, fats and carbohydrates via sugar release and with the aid of precision fermentation [31].

In addition to all the possible uses described above, the crop residues that cannot be converted into food are used for plant fertilisation, which is essential for organic vegan farming. This is done using various innovative methods such as green manure, green waste fertilisation, composting and humus formation [27]. Utilization via biogas plants to produce renewable energy and valuable fertilizer is also possible.

12. Claim: We need twice the agricultural area for a purely vegan agricultural system.

What is true: In fact, the opposite is correct. It is crucial that all land uses are included and the yields per unit area are compared in terms of plant and animal calories and proteins [36],[37]. Thus, in an agriculture with cows, the grassland areas, which are food suppliers for the cows and ultimately fertilizer suppliers for the fields, must also be included in the comparison. In vegan agriculture, plant residues, as often insinuated, must not simply rot on the field, but the latest findings and techniques such as green manuring, green waste fertilization, composting [27], humus build-up [35] and fermentation via biogas plants must be used. In this way, composting, humus production and biomass fermentation can be used to produce plant-based fertilizer, which, like manure and slurry, can be stored and used as needed.

Globally, a change to vegan agriculture can reduce agricultural land by 76% and arable land by 19% [36]. In Germany, the proportion is likely to be somewhat lower, since agriculture is hardly extensive, but mostly intensive. Nevertheless, enormous areas would also be freed up in Germany without animal husbandry.

On the one hand, this would enable less efficient but sustainable bio-vegan agriculture without artificial fertilizers and pesticides and, on the other hand, utilize the land against climate change and loss of biodiversity, e.g. through reforestation, renewable energy plants (solar, wind power) and nature reserves. Goals of energy transition and energy self-sufficiency can be combined with a shift to plant-based agriculture, e.g. by using grassland as a fermentation substrate supplier for biogas plants and providing important plant-based fertilizer via the fermentation residues after fermentation [39].

Emissions

Livestock advocates try to downplay livestock emissions and portray them as negligible.

13. Claim: In Germany, only 3.2% of CO2 equivalents come from livestock farming.

What is true: The German Federal Environment Agency states that about 5% (36 Mt. CO2eq of 762Mt. CO2eq) of greenhouse gases originate directly from animal husbandry [38]. The German Federal Environment Agency states that about 5% (36 Mt. CO2eq of 762Mt. CO2eq) of greenhouse gases originate directly from animal husbandry [38]. However, the shares of livestock production are much higher, because (1) emissions are missing that result from the production of artificial fertilizers for the huge livestock areas and (2) potential carbon sinks (carbon opportunity costs), i.e., the non-utilization of the sequestration potential of the livestock areas are not included. In addition, (3) the values for methane are calculated with a too low warming potential. For (1) and (2), the large foreign areas for animal feed, which are not included at all in the calculations of the Federal Environment Agency, are of particular importance.

Assuming that in Germany we would use all forage fields for humans instead of animals, 46% of the agricultural land used by Germany domestically and abroad would become free (i.e. domestic grassland and foreign forage fields). This is a very conservative assumption compared to the calculations of Oxford University, which determined a release of 76% of agricultural land on a global level [36]. Assuming that in Germany we would use all forage fields for humans instead of animals, 46% of the agricultural land used by Germany domestically and abroad would become free (i.e. domestic grassland and foreign forage fields). This is a very conservative assumption compared to the calculations of Oxford University, which determined a release of 76% of agricultural land on a global level [36]. For Germany, the scenario with 46% released land would result in greenhouse gas minimization potentials of at least 206 Mt CO2eq per year, which corresponds to 24% of greenhouse gas emissions and unused potentials (in contrast to the 3.2% mentioned by Prof. Windisch and the 5% of the Federal Environment Agency). The share would be even higher if the energy expenditures of animal agriculture (machinery, stables, slaughterhouses and cold stores, animal transports), the ongoing slash-and-burn of rainforests, fish farming and ocean fishing were included.

LWJ-SequPotDtl

14. Claim: The most climate-damaging emissions from agriculture are those of N2O, and these come primarily from the use of artificial fertilizers for growing animal feed.

What is true: Though N2O has a higher warming potential than methane (270 vs. 87 and 103, respectively), N2O emissions from livestock are comparatively low in terms of quantity, so that the climate change impact of these N2O emissions relative to total livestock emissions is only about 7% (relative to 206 Mt CO2eq, see assertion 13 and source [38]). Moreover, N2O from agriculture does not only originate from the decomposition of artificial fertilizers on the fields, but to a large extent also from the decomposition of cow manure on pasture and arable land [38].

15. Claim: The feedback (recycling) of non-edible biomass always causes the same climate gas effects, regardless of whether it is done via feeding to livestock, biogas production, green manure, composting or humus build-up.

What is true: In vegan agriculture, the decomposition of plants takes place by aerobic bacteria and leads to CO2 emissions. In cows, on the other hand, the decomposition of plants is anaerobic, which is accompanied by the emission of methane. Since methane is 87-103 times more potent than CO2, the recycling of carbon from biomass via cows is correspondingly more harmful to the climate.

If a biogas plant is used in vegan agriculture to produce methane and fertilizer, the plant initially produces methane, but this does not enter the atmosphere because it is converted to CO2 via combustion.

Organic livestock farming / pasture farming

Using the argument of so-called organic livestock farming, animal husbandry advocates try to present an alternative.

16. Claim: Organic livestock farming and especially pasture-based livestock are the solution.

What is true: In general, organic livestock farming as a substitute for conventional livestock farming is not feasible at all, since Germany does not have the necessary land. Moreover, organic livestock farming is not ecologically sustainable. Organic livestock farming is somewhat better for biodiversity than conventional livestock farming, but it is worse than the natural ecosystem that is the forest, which is actually to be compared. For the climate, organic livestock farming is at least as harmful as intensive livestock farming. Due to an average of 90% energy loss in the conversion of plant proteins and nutrients into meat, milk and eggs, animal products cause many times more harmful metabolites, especially greenhouse gases, than equivalent plant-based alternatives [19],[20]. This biochemical law cannot be overruled by organic livestock farming. On the contrary, animal products from organic livestock farming are usually overall even more harmful to the climate than animal products from conventional intensive livestock farming. The reasons for this are:

(1) Higher land requirements for forage production and grazing, and thus higher emissions from land use change [21],[22],[23]

(2) Lower, average yields per animal per year as animals are left alive longer [24]

(3) Higher methane emissions in ruminants due to higher shares of green forage [24].