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.