The full climate costs of agriculture including foregone land carbon storage

Estimates of the climate costs of agriculture typically do not count lost carbon storage from native vegetation on existing agricultural land. By assigning no climate cost or benefit to activities that increase or decrease demand for agricultural land, these estimates effectively treat such land as “free” from a climate perspective. Here, we produce comprehensive estimates of the full climate costs of agricultural products, including foregone carbon storage, for 270 products in 14 world regions or major agricultural countries. We also incorporate production emissions estimates that are physically consistent with each other and with national agricultural statistics, differing substantially from prior estimates in methods, comprehensiveness and results. When including the cost of foregone carbon storage, the global annualized climate cost of agriculture of ~34 Gt CO₂ eq/year matches energy emissions and is 3.5x typical estimates. Only ¼ of this cost occurs to produce crops consumed directly as food, and ~57% is for ruminant products. Differing regional costs reveal potential adverse effects of outsourcing production, but using regional versus global carbon costs would not typically change the directional outcomes of potential food policies.