Moderating the impact of agriculture on climate

Many options are available for reducing the impact of agriculture on climate; however, it is difficult to provide a comprehensive set of solutions because several aspects are still poorly understood. An overall assessment of the various impacts of agriculture on climate is presented. It focuses on the trade-offs among the relevant greenhouse gases (GHG), CO2, N2O and CH4, and the geochemical and biophysical interactions between agriculture and climate. Three spatial scales are examined: field, farm, and regional scale. At the field level, both GHG and energy fluxes are related to technical decisions by the farmer. At the farm level, strategic decisions on the choice of production systems are governed by economical constraints. Land use and landscape govern the biophysical factors that act on the regional climate when spatially integrated. At the regional level, national and regional policies on GHG emissions and surface forcing influence global climate. The biochemical and geophysical contribution of agriculture to climate need to be considered using new approaches in terms of global warming. The use of GCMs appears to be an adequate tool at this scale for assessing the global effect on climate, upon which smaller-scale effects will be superimposed.