Grazed and Confused? How much can grazing livestock help to mitigate climate change?


Grazed and confused? How much can grazing livestock help to mitigate climate change? These are ruminants. Ruminants have specialized stomachs containing microorganisms. This allows them to eat hard-to-digest plants like grass, unlike pigs and chickens. However, these microorganisms also produce methane, a powerful greenhouse gas. And the more fibrous the ruminants’ diets, the more methane is produced. Ruminants are responsible for the majority of greenhouse gas emissions from all livestock, and 11.6% of all human-related emissions. Cattle, being the most numerous species, account for most of ruminant emissions. Demand for meat and other animal products is expected to grow, and as a result, so are livestock emissions. This presents a problem, because if global warming is to be kept below the goal of two degrees Celsius global greenhouse gas emissions need to fall to zero by mid-century. And to achieve this, all human activities need to contribute to reducing emissions, including the livestock sector. While most agree that emissions from the livestock sector need addressing if we are to achieve our climate goals, how, and by how much, are more contested questions. In particular, when it comes to grass-fed livestock, some argue that research on their emissions ignores a crucial part of the picture: the potential for grass-fed ruminants to help remove carbon dioxide from the atmosphere. Specifically, they argue that by carefully managing the way animals graze the land, plants can be stimulated to grow more vigorously, taking more carbon dioxide out of the atmosphere via photosynthesis, leading to more carbon being stored in their shoots and especially in and around their roots. And that some of this carbon, when buried in the soil, may be converted into stable forms resistant to decomposition, rather than being turned back into carbon dioxide by soil microbes. The result: carbon’s long-term removal from the atmosphere, a process known as soil carbon sequestration. It’s claimed that when the greenhouse gas emissions from grass-fed ruminants are compared with the removals of carbon dioxide resulting from grazing, all the emissions from the grass-fed animals could be partially or even entirely offset. Some even claim that this sequestration effect from grazing could potentially offset all emissions from all forms of livestock production, and perhaps even solve the problem of climate change. This debate has left many policymakers and the public feeling confused. Can raising livestock really help mitigate climate change? And if so, by how much? To address these questions, an international group of researchers came together to provide answers. It’s important to note that there are many social, ethical, and environmental issues to think about when considering grass-fed livestock’s role in a sustainable food system, but the researchers’ analysis focused on just one important aspect of this wider picture: grass-fed livestock and the net balance of all their greenhouse gas emissions, accounting for both emissions and any removals via sequestration. The research did not compare grass-fed livestock with any other production system or species of livestock. First, they reviewed all sources of emissions from grass-fed livestock, including those from clearing natural land, producing animal feed, animal digestion, and animal manure. Next, using optimistic assumptions, they identified how much carbon could potentially be removed from the atmosphere if the way grazing is managed today were improved worldwide, so as to promote increased carbon sequestration. The research found that even if the sequestration potential from grazing were maximized at the global level, grazing livestock would still be a net contributor to the climate problem, and that the reduction in emissions that this could deliver would be small when compared to total emissions from the livestock sector. In some specific contexts, where the climate, soil, land-use history, and grazing management are just right, additional carbon can be removed from the atmosphere and sequestered in soils. But realistic rates for this are far below those claimed outside of the scientific literature and only rarely can sequestration outweigh the greenhouse gas emissions from grazing animals living on the land. Even where changes to grazing management do lead to sequestration, within decades of introducing the change in grazing, a new equilibrium is achieved between carbon entering and leaving the soil, and so the rate of sequestration falls back to a level close to zero. Meanwhile, animals still continue to emit greenhouse gases, contributing to climate change. Additionally, any sequestration gains may also be reversed later on through poor land management or a changing climate. So what conclusions can we draw about grazing livestock’s role in climate mitigation? Better grazing management is certainly worthwhile for many reasons. Yet grazing-induced removals via soil carbon sequestration do not offer a substantial mitigation opportunity. Grassland soils worldwide already contain vast carbon stores larger than all of the world’s forests, and importantly this stored carbon can be lost much faster than it can be accumulated again . Which means that stopping poor grazing practices that degrade land through overuse or misuse should be a priority, as should halting the conversion of grasslands into new cropland which quickly releases up to half the carbon stored. And what does this mean for grass-fed livestock’s role in sustainable food systems? Answering that question adequately requires a comprehensive sustainability assessment, reaching way beyond climate change issues: an undertaking far beyond the scope of this research. Nevertheless the study does contribute one important piece of the wider puzzle. Growing emissions from the livestock sector remain a problem. And to reduce emissions from the sector and meet our climate goals we need to make changes to animal product consumption, as well as production. In other words, whatever the animal species or method of production, high-consuming individuals and nations have to moderate their intake of animal-sourced foods.

Comments 12

  • Excellent video. Alan Savoury and his institute are the main proponents of the idea that cattle can add carbon and water and help green dry lands. It's a total sham funded by animal agriculture industry. They have not produced a single legitimate scientific paper, except some pseudo science. But they are very prolific on the internet and have high production videos in documentary style.

  • 6:02 "…grazing-induced removals via soil carbon sequestration do not offer a substantial mitigation opportunity."

  • You can graze livestock without needing to clear land and produce animal feed, which I'm sure is one of the main carbon emissions accounted for. Grasslands make grass without tractors and chainsaws.

  • No mention of glomalin and how it stabilises carbon in grasslands and consumes methane as a food source therefore making purely grassfed beef ( not fed inputs as in the study ) methane neutral.

  • Thank you. Great video and interesting study.

  • I'm very pleased to see this. My understanding of soil and atmospheric chemistry led me to think it was highly unlikely that ruminants could be involved in any net sequestration, and this study confirms that. The proponents of 'mob grazing will solve climate change' have an agenda, which is to continue farming (and eating!) beef. Savory is not a scientist, and certainly the initial 'reports' he produced were laughable with their lack of scientific rigour. More recently, better studies have been done, showing that in certain circumstances, some types of grazing practices can help soils gain carbon, but as this video explains, these gains would not continue year on year 'for ever', as all (natural) ecological systems get to equilibrium eventually – even forests don't permanently sequester carbon year on year.

    The solution, for meat eaters, is to eat less meat and lower carbon meat such as chicken and pig. For those who say they have to eat beef or lamb/mutton make it a rare treat (no pun intended) so your annual ruminant emissions are very low. The easiest thing to do is to go veggie – it's not difficult and quality of life is no different from those who continue eating meat.

  • The whole methodology fails to consider two very basic item: 1. CO2 emissions and CH4 emissions come from grass, therefore are part of a cyclical system, and do not add in any way net CO2 to the atmosphere. CH4 converts into CO2 after 10 years and sequestered again. 2. N2O emissions are the same with or without cattle, since they are a result of degradation of nitrogen by bacteria, no change whether the plant matter goes or doesn't go through the digestive system of the cow. So, you cannot compare emissions from livestock with emissions from cars for example, which add always CO2 to the atmosphere. Of course deforestation causes increase of CO2, but then let's talk about soy too, ok? Now, the video fails to capture that we talk here about CO2equivalent, NOT CO2. This is misleading, and CO2e is an abstract concept. Fails to also point at consensus in scientific community, that methane is NOT an issue until CO2 emissions increase are reduced to 0. And then it fails to mention also that 70% of atmospheric increase in methane is due to gas and oil industry, and the other majority due to biomass burning and wetland increase emissions in the last 10 years. Also it fails to acknowledge that current livestock emissions levels are similar to those in the Neolithic, before the megafauna extinction. It is a pity to see this prevalence of a totally flawed concept and so much energy dedicated to malign a sector which has no actual impact on climate change, knowing quite well where the actual culprits are. Also, again using a long time debunked total emissions number, thanks to the sloppy job of FAO reports (no amount of articles published afterwards by the authors saying these emissions should be taken with a grain of salt will undo the damage done).

  • BULLSHIT ๐Ÿ˜ƒ Did those scientists take into account all the methane farting humans contributing to global warming?

  • I find it very odd that this study recognises that grasslands are extremely important and that the soils beneath grassland store more carbon than those of forests, but that they do not mention the fact that grasslands have to be grazed (responsibly) in order to maintain them. I also need to check which reference they used for the amount of methane produced by cows since the studies often quoted were conducted on stressed cows standing in tents and not grazing pasture.

  • if using the land to grow crops releases more carbon emissions what are people supposed to eat? If the grains, vegetable oils & sugar is killing us all and the agro-farming monocultures of all kinds are killing the soil why is meat from a biologically natural system bad? I can't see how this makes any sense how did the grasslands sequester so much carbon in the first place? Why are farmers using intensive cell grazing that mimics tight herds fearful of pack predators and building top soil every yr while drought proofing their farms? Who paid for the research your quoting?

  • That's the worst flawed bunch of propaganda I ever witnessed.

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