It seems to be commonly accepted that cows are bad for the environment (methane emissions contributing to global heating, soil damage) and are a drain on resources that could be put to better use (grains, water). These hypotheses are false when scrutinised objectively. Furthermore, their opposites are true – cattle can be beneficial to the environment, improve soils and halt erosion, reverse desertification, restore rangelands and, remarkably, convert carbohydrates that are inedible to humans (e.g. grass, hay) into nutritious proteins and fats (e.g. beef, milk).
Green House Gasses (GHGs)
For those with an awareness of global heating and the looming climate catastrophe, the methane emissions of ruminants, cattle in particular, may be a concern. Methane (a carbon with 4 hydrogens attached) is a potent GHG, although it is in the atmosphere for a shorter time than carbon dioxide (~10 years vs. ~1,000 years) and it has a much lower concentration (methane concentration is ~0.5% of that for carbon dioxide). Still, methane has ~30 times more heating potential than the same mass of carbon dioxide.
About 60% of atmospheric methane is attributed to human activity. The remainder comes from natural sources – wetlands, underwater methane hydrate release, methane stores in melting permafrost, surface venting from underground gas deposits, wildfires and termites.
Besides methane-belching cattle (and other ruminants), other human-attributed sources of methane include fossil fuel mining and use (including natural gas), landfills, flooded rice paddies and human-induced forest fires (e.g. land clearing).
Methane is the major component of natural gas, and its drilling, extraction, piping and burning can result in leakage into the atmosphere. Technologies are available to reduce these effects, however they require new policies and investment. The US is currently transitioning to a natural gas economy, which will not fight global heating and may make it worse if methane release is not managed.
The contribution of rice-paddies is also important, as they can be flooded all year round, and anaerobic bacteria in underwater soil are methane-emitters (as they are in naturally-occurring wetlands). Drying out the paddies for part of the year temporarily stops this, but introduces aerobic bacteria that can emit nitrous oxide gas, a significantly more powerful GHG than methane. Likewise, organic material in waste landfills is broken down by methane-emitting bacteria.
So, it’s complicated, and the danger is that cows become a ‘scapegoat’, the targeting of which will be ineffective at mitigating global heating in the presence of more wide-ranging mechanisms.
“Livestock’s Long Shadow”
In 2006, the United Nations Food and Agriculture Organisation (FAO) released a report with the title “Livestock’s Long Shadow”, in which they concluded that cattle emit more GHGs than all of transport combined. This led to sensationalist headlines worldwide that penetrated public perception.
It might have been anticipated that, before releasing the report, someone at the FAO would have scratched their head and thought “hang-on, that can’t be right!” and re-thought their model. In any case, once published, external scientists pointed out the fundamental flaws in the model, making the conclusion wrong. The FAO accepted they were wrong, however, it took another 4 years (2010) before they produced a more nuanced report, and by then lasting damage to the public reputation of cattle had been done.
The US Environmental Protection Agency estimates that beef cattle contribute ~2% to US total GHG emissions, the rest of the livestock sector another ~2%, and plant-based agriculture ~5%. For perspective, fuel combustion (including transport) and industrial processes make up ~80% of GHG emissions. Other analyses have produced similar figures.
The contribution of cattle to GHG emissions globally is higher than these figures, mainly due to less efficient farming practices in developing countries. Rather than wealthy countries cutting back on their meat consumption (e.g. meatless mondays), which would have a negligible effect on GHG emissions, it would be more effective to use aid programs or other means to export efficient farming models to developing countries, improving the lot of farmers and increasing food-security for their region.
Atmospheric methane is accelerating – why?
Atmospheric methane levels started to plateau in the 1990s, and for the period 2000-2007 methane concentration was relatively steady. However, after 2007, methane concentration resumed rising and in the past 4 years (2014-18) that rise accelerated. The increase has been worldwide, but somewhat greater over the tropics and low northern temperate latitudes. The cause of this rise is not understood, and it has the potential to undermine global temperature targets.
According to the US Department of Agriculture, cattle numbers in the US peaked in the 1970s and are in decline, mostly from farming and productivity advances. Globally, cattle numbers have been steady this century at, or just below, 1 billion head. On that basis, it is unlikely that cattle have driven this recent acceleration.
Of most concern is that it may be climate feedback – warming feeding warming. For example, global heating could increase anaerobic microbial activity in tropical wetlands, that in turn emit more methane and fuel global heating. As well, an increase in flooding events associated with global heating will increase the opportunity for microbial fermentation. Alternatively (or as well) biomass burning (especially forest clearing) is accelerating unchecked in many tropical regions (e.g. Amazon).
However, mining and burning fossil fuels, and the transition to natural gas economies, are likely significant sources of emissions and ready targets for regulation and reduction. For example, the acceleration in methane emissions
1. Pasture. There are around ~100 million head of cattle in the US, of which ~11.5 million were raised in high-capacity feed-lots (based on 2018 data). Thus, the majority of cows are pastured. Furthermore, the pastures are on rangeland (grasslands), not agricultural land. If the surface of the Earth is taken as a whole (including oceans), then rangeland pastures make up about 14%, whereas land suitable for cultivation is just 4%. Rangelands are not suited to high-intensity mono-crop agriculture (e.g. soybean production), which has resulted in soil erosion on these lands. Hence, livestock and crop agriculture need not significantly compete for land resources.
2. ‘Grain-fed’: It has been argued that ‘grain-fed’ cattle consume a resource that would be better directed to feeding humans. However, the term ‘grain-fed’ is a misnomer. Up to 90% of cattle feed is waste material from crop agriculture or food processing, and not edible by humans (for example, wheat/corn chaff). If this organic material was not fed to cattle, it would go to landfill and be degraded by bacteria that would release methane into the atmosphere (bypassing the cow). By fermenting this wastage in their rumens instead, ‘grain-fed’ cattle produce nutritious meat out of useless waste.
There is naturally concern about animal welfare in high-intensity feed lots, however, even that topic is complicated and I won’t explore it here, especially as the majority of cattle are pastured throughout life and perhaps only finished on ‘grain-feed’. Certainly, it would be preferable that all cattle were pastured, and we should support ethical farming practices by buying produce from those farms.
3. Fermentation: Regardless of the specifics of the feed, cows live on fibrous carbohydrate of little nutrient content. In particular, their feed is low-protein and low-fat (there is some), yet protein and fat are the bulk of what constitutes a cow. This disproof (for cows at least) that you are not what you eat, is accomplished by microbes in the cow rumen that ferment carbohydrate feed and produce byproducts that provide complete nourishment and building materials for the cow. A cow can be thought of as a masterpiece of carbohydrate fermentation – sauerkraut taken to the extreme. As the rumen sits ahead of the cow’s intestinal system, fermentation gasses are released by belching. Nothing much of a gaseous nature comes out the other end.
Cattle are grazing animals that naturally congregate in herds, and compact herding has significant benefits for the animals and the grasslands they feed on. Indeed, grasslands co-evolved with enormous herds of ruminants (buffalo, bison, elephants, wildebeest etc). Therefore, it makes sense to raise cattle according to their natural behavioural model.
These animals herded for protection, and grazed in one place but only for a short time – until the grass had been mostly eaten and/or their dung became a deterrent. The herd would move on, leaving the pasture to regenerate. There are several factors at work:
1. Plants are naturally fertilised and watered by animal dung and urine.
2. Animal excrement adds nutrients to the soil and improves water retention.
3. Improvement in soil encourages larger plants that support more animals.
4. Hooves trample inedible plants, increasing sunlight penetration and forming a natural mulch that retains water and reduces runoff with heavy rains.
5. Hooves break up hard soil crusts, enabling water penetration and seed germination.
6. Healthier grasslands can sequester carbon – photosynthesis converts the GHG carbon dioxide to carbon that can be used to grow the plant (carbohydrates), or gets stored in root systems (perennial grasses have deeper root systems that crop annuals) or taken in by soil fungi (that can store it for thousands of years). It’s not often acknowledged that ruminants have the potential to indirectly sequester carbon.
7. Some soil bacteria that consume methane can thrive in the presence ruminate herds.
To translate these considerations to animal husbandry, a method known as multi-pasture (MP) farming is employed. It’s simple: the landholding is divided into smaller paddocks, and cows are confined to one until the pasture is beginning to be depleted. They are then just moved to another paddock to allow regeneration.
It may sound simple but the ecological results can be spectacular (see image). The idea has been promoted by Allan Savory for decades. I encourage you to watch his video (22 mins) in which he talks about desertification and its reversal with livestock, and shows some field examples. Some of the before-after images are remarkable, and a challenge to anyone who proposes livestock are a threat to the environment. Livestock may well help save us.
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More on forage livestock production from Peter Ballerstedt.
The Savory Institute: https://www.savory.global