Cutting Carbon with Knife and Bin: The Role of Diet and Food Recycling in the Food System of Ulaanbaatar, Mongolia

The global food system (FS) contributes one-third of anthropogenic greenhouse gas (GHG) emissions, yet evidence remains heavily skewed toward temperate-climate cities, leaving cold-climate cities in the Northern Hemisphere understudied. Here, the GHG footprint (GHGF) of the entire FS in Ulaanbaatar, Mongolia, is assessed, accounting for six subsystems spanning food production, processing and storage, retail, transportation, consumption, and food waste. The baseline indicates that the food waste (FW) subsystem dominates the total GHGF (47.13 kg CO2eq/kg), contributing 49.3% of overall emissions. It exceeds those from agricultural food production (AFP) (18.5%) and, food & food waste transportation (FFWT) (22.6%). We further evaluate two mitigation scenarios. (1) Under a dietary shift scenario aligned with national dietary guidance, the total GHGF decreases 14.4% while the FW subsystem remains the largest contributor, (2) but the food waste reduction scenario yields a comparable reduction of 15.9%. The findings revealed that decarbonisation lever efficiency can be done through food waste reduction while supporting a circular valorisation strategy, including waste-related GHG liabilities as an energy source in cold-climate cities.