The relationship between livestock production and climate change is the subject of hot debate, with arguments for major shifts in diets and a reduction in livestock production. This Perspective examines how global assessments of livestock-derived methane emissions are framed, identifying assumptions and data gaps that influence standard life-cycle analysis approaches. These include inadequate data due to a focus on industrial not extensive systems; errors arising due to inappropriate emission factors being applied; questions of how global warming potentials are derived for different greenhouse gases and debates about what baselines are appropriate. The article argues for a holistic systems approach that takes account of diverse livestock systems-both intensive and extensive-including both positive and negative impacts. In particular, the potential benefits of extensive livestock systems are highlighted, including supporting livelihoods, providing high-quality nutrition, enhancing biodiversity, protecting landscapes, and sequestering carbon. By failing to differentiate between livestock systems, global assessments may mislead. Inappropriate measurement, verification and reporting processes linked to global climate change policy may in turn result in interventions that can undermine the livelihoods of extensive livestock-keepers in marginal areas, including mobile pastoralists. In the politics of global assessments, certain interests promote framings of the livestock-climate challenge in favour of contained, intensive systems, and the conversion of extensive rangelands into conservation investments. Emerging from a narrow, aggregated scientific framing, global assessments therefore can have political consequences. A more disaggregated, nuanced approach is required if the future of food and climate change is to be effectively addressed.