The cow is (not) a climate killer?!

Ei­nige Ver­fech­ter der Tier­hal­tung, bei­spiels­weise der Tier­er­näh­rungs-Ex­perte Prof. Wil­helm Win­disch, die Tier­ärz­tin Dr. Anita Idel, der Bauer Sven Lo­renz, der Agrar­lob­by­ist Prof. Frank Mit­loeh­ner und die Kö­chin Sa­rah Wie­ner be­haup­ten in In­ter­views, Vor­trä­gen, Ar­ti­keln, Lob­by­platt­for­men und Bü­chern wie­der­keh­rend: „Die Kuh ist kein Kli­ma­kil­ler.“ Wir ha­ben uns 16 der gän­gigs­ten Be­haup­tun­gen an­ge­se­hen, ha­ben sie ei­nem in­ten­si­ven Fak­ten­check un­ter­zo­gen und kom­men zu dem ein­deu­ti­gen Fa­zit: „Die Kuh als Nutz­tier ist ein Klimakiller.“

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 damaging a cow is for the climate: a cow kept on pasture needs approx. 6700 m2. Pro Jahr stößt eine Kuh ca. 100 kg Me­than aus. Dies ent­spricht bei ei­nem GWP (Glo­bal Warm­ing Po­ten­tial) von 87 ca. 8700 kg CO2-Äqui­va­lente. Pro Qua­drat­me­ter ver­ur­sacht eine Kuh so­mit 1,3 kg CO2eq pro Jahr. Eine un­ge­sät­tigte Wei­de­flä­che se­ques­triert pro Qua­drat­me­ter und Jahr aber nur 0,2 kg CO2 [9]. Without taking other factors into account, a cow kept on pasture damages the climate by a net 7370 kg CO2eq per year. Other factors further increase the climate impact of the cow, such as methane emissions from the manure, the carbon opportunity costs of maintaining the 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: Durch die Be­wei­dung über die so­ge­nannte “Re­ge­ne­ra­tive Wei­de­wirt­schaft”  (Re­ge­ne­ra­tive Gra­zing, Ho­li­stic Gra­zing) wird das Gras­wachs­tum incl. der Wur­zeln der­art ge­stei­gert, dass es zu ei­ner stän­di­gen Netto-CO2-Se­ques­trie­rung über den Bo­den kommt.

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: Es stimmt, dass durch Ver­füt­te­rung von Gras an Wie­der­käuer die Nah­rungs­mit­tel­pro­duk­tion er­höht wer­den könnte, denn für diese Agrar­flä­chen be­steht keine Nah­rungs­kon­kur­renz und ein Um­bruch des Gras­lands ist öko­lo­gisch nicht sinn­voll. Eine zu­sätz­li­che Nah­rungs­mit­tel­pro­duk­tion über Gras­land ist aber bei ei­nem rein pflanz­li­chen Er­näh­rungs­sys­tem gar nicht er­for­der­lich, denn die be­stehen­den Fut­ter­mit­te­lä­cker rei­chen mehr als aus, um alle Men­schen aus­rei­chend zu ver­sor­gen [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: Bei Kü­hen er­folgt die Ver­dau­ung maß­geb­lich durch an­ae­robe Bak­te­rien, wel­che die Pflan­zen­be­stand­teile u.a. schließ­lich in Gülle und Me­than um­wan­deln. Viel sinn­vol­ler ist es, wenn ae­robe Bak­te­rien die Um­wand­lung der Pflan­zen in Dün­ger au­ßer­halb von Tie­ren über­neh­men, denn dann ent­steht nicht das ex­trem kli­ma­schäd­li­che Me­than. Diese in­no­va­ti­ven Tech­ni­ken wer­den z.B. bei der Gründün­gung, beim Kom­pos­tie­ren und beim Hu­mus­auf­bau an­ge­wandt. Als Er­satz für Stick­stoff-Kunst­dün­ger kön­nen Le­gu­mi­no­sen ge­nutzt wer­den, wel­che dann ent­we­der ge­ern­tet oder als Gründün­ger, Cut & Carry — Be­stand­teil oder zum Kom­pos­tie­ren und zum Hu­mus­auf­bau ver­wen­det wer­den kön­nen [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]. Es be­steht aber keine Not­wen­dig­keit, diese an Tiere zu ver­füt­tern. Je nach Art kön­nen sie auch von Men­schen ge­ges­sen wer­den (z.B. Lu­pine, Hül­sen­früchte). Dar­über hin­aus die­nen im bio­zy­klisch-ve­ga­nen An­bau Zwi­schen­früchte, in­dem sie ge­mulcht und un­ter­ge­pflügt wer­den, dem wich­ti­gen Zweck der Gründün­gung [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]. Dies sind vor­ran­gig Raps­ex­trak­ti­ons­schrot, So­ja­ex­trak­ti­ons­schrot, Tre­ber und Tres­ter. Hier­bei han­delt es sich um die ei­weiß­rei­chen Reste der Pflan­zen­öl­ge­win­nung, um die ei­weiß­rei­chen Rück­stän­den beim Brauen und um die Press­rück­stände von Obst und Ge­müse. Alle diese Ne­ben­pro­dukte wer­den schon seit lan­ger Zeit auch di­rekt für Nah­rungs­mit­tel für Men­schen ge­nutzt, z.B. als Flei­scher­satz, für Pro­te­in­pul­ver, für Brot, für Spi­ri­tuo­sen und für Pek­tin. Seit kur­zem kön­nen über neue Ver­fah­ren Ex­trak­ti­onssch­rote und Tre­ber aber auch zur Her­stel­lung von pro­te­in­rei­chem, pflan­zen­ba­sier­tem Fleisch ver­wen­det wer­den [32],[33],[29].

Zu­künf­tig wird es auch Ver­fah­ren und Tech­no­lo­gien ge­ben, nicht-ess­bare Bio­masse höchstef­fi­zi­ent in für Men­schen hoch­wer­tige Le­bens­mit­tel zu ver­wan­deln. Bei­spiels­weise ist es Un­ter­neh­men ge­lun­gen, das auf der Erde am häu­figs­ten vor­kom­mende Pro­tein Ru­bisco aus Pflan­zen zu ex­tra­hie­ren [30]. biomass into all conceivable proteins, fats and carbohydrates via sugar extraction and with the aid of precision fermentation [31].

Er­gän­zend zu al­len dar­ge­stell­ten Nut­zungs­mög­lich­kei­ten, die­nen die nicht in Nah­rung ver­wan­del­ba­ren Reste des Pflan­zen­baus der für die bio-ve­gane Land­wirt­schaft es­sen­ti­el­len pflanz­li­chen Dün­gung. Dies er­folgt über ver­schie­dene in­no­va­tive Ver­fah­ren, wie Gründün­gung, Grün­schnitt­dün­gung, Kom­pos­tie­rung und Hu­mus­auf­bau [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]. So müs­sen in eine Land­wirt­schaft mit Kü­hen auch die Grün­flä­chen, wel­che Nah­rungs­lie­fe­ran­ten der Kühe und letzt­end­lich Dün­ge­lie­fe­ran­ten für die Äcker sind, in den Ver­gleich ein­flie­ßen. Bei ei­ner ve­ga­nen Land­wirt­schaft dür­fen Pflan­zen­reste, wie oft un­ter­stellt, nicht ein­fach auf dem Feld ver­rot­ten, son­dern es müs­sen neu­este Er­kennt­nisse und Tech­ni­ken wie Gründün­gung, Grün­schnitt­dün­gung, Kom­pos­tie­rung [27], humus build-up [35] und Ver­gä­rung über Bio­gas­an­la­gen zum Ein­satz kom­men. So lässt sich über Kom­pos­tie­rung, Hu­mu­ser­zeu­gung und Bio­mas­se­ver­gä­rung pflanz­li­cher Dün­ger her­stel­len, der ebenso wie Mist und Gülle la­ger­bar und be­darfs­ge­recht ein­setz­bar ist.

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]. Die An­teile der Tier­hal­tung sind aber we­sent­lich hö­her, denn es feh­len (1) Emis­sio­nen, die durch die Her­stel­lung von Kunst­dün­ger für die rie­si­gen Tier­hal­tungs­flä­chen an­fal­len und (2) po­ten­ti­elle Koh­len­stoff­sen­ken (Car­bon-Op­por­tu­ni­täts­kos­ten), also die Nicht-Nut­zung des Se­ques­trie­rungs­po­ten­ti­als der Tier­hal­tungs­flä­chen. Zu­dem wer­den (3) die Werte für Me­than mit ei­nem zu ge­rin­gen Er­wär­mungs­po­ten­tial be­rech­net. Für (1) und (2) fal­len ins­be­son­dere die gro­ßen Aus­lands­flä­chen für Fut­ter­mit­tel ins Ge­wicht, die in den Rech­nun­gen des Um­welt­bun­des­am­tes über­haupt nicht ein­be­zo­gen werden.

Ginge man da­von aus, dass wir in Deutsch­land alle Fut­ter­mit­te­lä­cker an­statt für Tiere für Men­schen nut­zen wür­den, wür­den 46% der von Deutsch­land in­län­disch und aus­län­disch ge­nutz­ten Agrar­flä­chen frei (d.h. hie­si­ges Grün­land und Aus­lands-Fut­ter­mit­te­lä­cker). Dies ist eine sehr kon­ser­va­tive An­nahme im Ver­gleich zu den Be­rech­nun­gen der Ox­ford Uni­ver­si­tät, die auf glo­ba­ler Ebene ein Frei­wer­den von 76% der Agrar­flä­chen er­rech­ne­ten [36]. Für Deutsch­land er­gä­ben sich im Sze­na­rio mit 46% frei­wer­den­der Flä­chen Treib­haus­gas­mi­ni­mie­rungs­po­ten­tiale von min­des­tens 206 Mt CO2eq pro Jahr, was 21% der Treib­haus­gas­emis­sio­nen und un­ge­nutz­ten Po­ten­tiale ent­spricht (im Kon­trast zu den von Prof. Win­disch ge­nann­ten 3,2% und den 5% des Um­welt­bun­des­am­tes). Der An­teil wäre noch hö­her, würde man die En­er­gie­auf­wände der Tier­hal­tung (Ma­schi­nen, Ställe, Schlacht- und Kühl­häu­ser, Tier­trans­porte), die fort­dau­e­r­en­den Brand­ro­dun­gen der Re­gen­wäl­dern, die Fisch­zucht und die Oze­an­fi­sche­rei miteinbeziehen.

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: Die Rück­füh­rung (Re­zy­klie­rung) der nicht-ess­ba­ren Bio­masse ver­ur­sacht stets die glei­chen Kli­ma­gas­wir­kun­gen, un­ab­hän­gig da­von, ob sie über die Füt­te­rung an Nutz­tiere, über Bio­gas­ge­win­nung, Gründün­gung, Kom­pos­tie­rung oder Hu­mus­auf­bau erfolgt.

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].