Ambiguity in the Land Use Component of Mitigation Contributions Toward the Paris Agreement Goals

Abstract Land use, land use change, and forestry (LULUCF) activities, including deforestation and forest restoration, will play an important role in addressing climate change. Countries have stated their contributions to reducing emissions and enhancing sinks in their Nationally Determined Contributions (NDCs); in 2023, the Global Stocktake will assess the collective impact of these NDCs. Clarity in the contribution of LULUCF to NDC targets is necessary to prevent high LULUCF uncertainties from undermining the strength and clarity of mitigation in other sectors. We assess and categorize all 167 NDCs and find wide variation in how they incorporate LULUCF; many lack the clear information necessary to understand what land‐based mitigation is anticipated. The land sector is included in 121 NDCs, but only 11 provide a LULUCF target that can be fully quantified using information presented or referenced in the NDC. By developing alternative scenarios from a subset of 62 NDCs (89 countries), we estimate that ambiguity in LULUCF contributions causes an uncertainty range in the anticipated LULUCF sink in 2030 of magnitude 2.9 GtCO2eq/year—larger in size than our best estimate for the LULUCF sink of −2 GtCO2eq/year. Clearer communication of data sources and assumptions underlying the contribution of land use to mitigation efforts is therefore important for ensuring a robust Global Stocktake and ambitious emissions reductions. We find that guidance under the Paris Agreement may improve the clarity of future NDCs but is not sufficient to eliminate ambiguities. We therefore recommend that LULUCF targets should be presented and accounted for separately from other sectors.