Reduced benefits of climate-smart agricultural policies from land-use spillovers

Agricultural practices that enhance soil carbon are increasingly being included in domestic climate strategies. The potential for these practices to affect productivity means that associated changes in land use can substantially alter net climate effects. Here we combine estimates of links between total factor productivity (TFP) and cropland use in each country with estimates of carbon emissions for cropland expansion to define TFP–emission links for each country pair. We then calculate the impact of TFP changes on both domestic and global emissions. In a scenario whereby practices reduce TFP by 5%, consistent with recent findings for cover cropping, we show that the net climate benefits of these practices are reduced in most countries—and by 70% in the United States and 80% in Europe. We also find stark contrasts between domestic and global climate impacts of TFP changes, highlighting the pitfalls of basing climate policy solely on domestic emissions targets.