Evaluating Global Plant-Only Diet Emission Claims: A Critical Systems Review Based on Livestock Phase-Out Scenarios and Land-Use Constraints

Sukumar Radrapu

Abstract: Several prominent modelling studies claim that eliminating global livestock agriculture and transitioning humanity to a plant only diet would yield substantial greenhouse gas (GHG) reductions and unlock planetary-scale carbon sequestration. Notably, Eisen and Brown (2022) estimate that a 15-year global livestock phase-out could offset approximately 1,680 Gt CO₂ equivalent over the century, representing up to 68% of required mitigation to remain below a 2 °C warming trajectory. Such conclusions influence government policy, institutional food procurement frameworks, and sustainability narratives. However, these results depend on strong assumptions: (a) that current cropland is sufficient to sustain a global plant-only diet, (b) that emissions associated with human-inedible feed biomass are fully avoidable, (c) that manure offers no climate mitigation value as a fertiliser or biogas input, and (d) that additional cropland demand does not trigger conversion of peatland soils-one of the highest carbon-release land-use transitions known. Using FAO livestock emissions baselines, Poore and Nemecek (2018) land datasets, Eisen and Brown's PHASE-POD modeling logic, and modelling results from Radrapu (2025), this review constructs 5-, 10-, 20-, 50-, and 100-year livestock phase-out timelines. When livestock feed-related emissions are removed and manure is modelled as a circular nutrient and energy system, global livestock emissions are approximately 2.429 Gt CO₂e year^-1, nearly equal to the estimated 2.435 Gt CO₂e year^-1 operational emissions associated with an estimated 996.77 Mha of additional cropland required for a global plant-only food system. Over 100 years, the difference between maintaining livestock and switching to a plant-only global diet remains within ?0.30 Gt CO₂e, effectively negligible. However, if 20% of that required cropland is sourced from peatlands, a one-time release of 2,192.7 Gt CO₂ overwhelms all modeled mitigation potential, resulting in a significantly worse climate outcome than maintaining livestock. Findings indicate that large-scale claims of climate benefit from a global plant-only diet are highly sensitive to land-use assumptions, manure treatment logic, and carbon-rich soil exposure, and therefore should be interpreted with caution. Further applied research is required before global policy recommendations are made.

Keywords: Plant-based diet, livestock emissions, manure valorisation, peatlands, global food systems, land-use change, mitigation modeling, agricultural sustainability

How to Cite?: Sukumar Radrapu, "Evaluating Global Plant-Only Diet Emission Claims: A Critical Systems Review Based on Livestock Phase-Out Scenarios and Land-Use Constraints", Volume 14 Issue 12, December 2025, International Journal of Science and Research (IJSR), Pages: 62-63, https://www.ijsr.net/getabstract.php?paperid=MR251201134221, DOI: https://dx.doi.org/10.21275/MR251201134221