Crop productivity and the global livestock sector: Implications for land use change and greenhouse gas emissions

The livestock sector accounts for 30% of global land area and is a major driver of land use change. The price reductions generated by crop yield increases should, ceteris paribus, encourage farmers to replace some of the grass in ruminant rations with crops. This would lead to land sparing and related carbon dioxide emission reductions in regions where the feed productivity per unit of area is higher for cropland than for grassland. Six land cover types are distinguished in GLOBIOM: cropland, grassland, short rotation tree plantations, managed forest, unmanaged forest and other natural vegetation. Depending on the relative profitability of the individual activities, and on the inertia constraints, the model can switch from one land cover type to another. Comprehensive greenhouse gas accounting for agriculture and land use change is implemented in the model. Crop yield development will play a critical role in future land use dynamics. Indeed, it will determine the requirements for additional cropland, and also have a strong impact on grassland expansion.