Methods used in Quantifying Green House Gas Emissions from the Food Systems

This document encompasses the a collection of studies from literature that have used different methods to estimate greenhouse gas emissions from the different stages of the food system. Methodology: We conducted a comprehensive review of 124 methods used in estimating greenhouse gas emissions from the food system. Through extensive debates and rounds of discussions, we categorized these methods into Inventory, Life cycle analysis, process based-models, input-output models, direct measurements, and remote sensing. The life cycle analysis (LCA) category focuses solely on evaluating the environmental impacts and services throughout the life cycle of a food system, estimating GHG emissions based on energy and material inputs/outputs. Inventories encompass methods such as IPCC tiers 1, 2, and 3, as well as bottom-up emissions estimation approaches. Process-based models consist of various components, including diet models, biophysical models for land use related to crops and livestock, IGES GHG calculation method, and the LandGEM model. Direct measurements involve techniques such as static chambers, Drager-tube techniques, and eddy covariance. The input-output (IO) method estimates GHG emissions by tracing inputs and outputs across the economy, capturing interconnections between sectors and providing insights into product emissions. Remote sensing is the utilization of satellite or aerial imagery and remote sensing technologies to monitor emissions across large geographic areas. Methodology: We conducted a comprehensive review of 124 methods used in estimating greenhouse gas emissions from the food system. Through extensive debates and rounds of discussions, we categorized these methods into Inventory, Life cycle analysis, process based-models, input-output models, direct measurements, and remote sensing.