Sequencing food-waste prevention and biowaste recovery for greenhouse-gas mitigation

Food and green municipal waste sits at an awkward point in climate policy. The best tonne is the one never produced, but many tonnes are already collected poorly, dumped, landfilled or left outside formal systems. This study asks how prevention and recovery should be sequenced when countries differ in waste flows, energy systems and capacity to act. We combined World Bank What a Waste 3.0 data, World Development Indicators, Ember electricity carbon intensity, ecoinvent-derived process parameters and uncertainty analysis for 217 countries and economies. In 2022, these countries generated 1.064 Gt of food and green municipal waste. Of this, 516 Mt. entered landfills, dumps, uncollected streams or unaccounted treatment in countries with treatment data, implying a first-pass methane screening estimate of 514 Mt. CO₂-eq/yr. This value is a screening estimate of methane opportunity, not a substitute for national greenhouse-gas inventories. Prevention was the most stable country-level priority. Recovery mattered where methane avoidance, substitution benefits and operating readiness aligned. The result is a practical way to sequence prevention and recovery, rather than a universal technology ranking.