The Global Livestock Environmental Assessment Model is a modelling framework that simulates the environmental impacts of the livestock sector. It represents the bio-physical processes and activities along livestock production chains under a life cycle assessment approach. The tool includes estimation of greenhouse gas emissions from each stage of production. The model covers emissions of methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). The aim of GLEAM is to quantify production and use of natural resources in the livestock sector and to identify environmental impacts of livestock in order to contribute to the assessment of adaptation and mitigation scenarios to move towards a more sustainable livestock sector.