Next-Generation Harmonized Land-Use Forcing Datasets for Global Carbon and Climate Models

Land-use change is an essential forcing dataset for climate and carbon cycle models, prescribing both the biogeophysical boundary conditions of the land surface as well as the land-based carbon sinks and sources. These datasets are built upon model requirements of a consistent set of variables and formats throughout the historical period as well as into future scenarios. Over the past two decades, both the ability of carbon and climate models to simulate land-use change, and the land-use datasets themselves, have advanced from relatively simple representations of 4 land-use types and their related transitions, to datasets that represent 13 land-use types, their transitions, as well as multiple data layers describing the detailed management of those land-use types. The Land-Use Harmonization (LUH) dataset has been used in both CMIP5 and CMIP6 experiments, as well as over 10 Global Carbon Budgets (GCBs), ISIMIP, IPBES, and will be used again in CMIP7 with several new features and new future scenarios, all provided at a resolution of 0.25 degrees for the years 850-2100 and beyond. In this presentation we will provide an overview of this data product, including recent updates to the historical dataset developed for GCB and comparisons with previous versions. We will present details of the 7 new harmonized future land-use scenarios developed for ScenarioMIP, including new variables used to model land-based Carbon Dioxide Removal (CDR) technologies such as BECCS and Re/Afforestation. Finally we will discuss our plans for new land-use datasets within the “Combining LAnd-use, modeling and Remote-sensing to Transform carbon budgets” (CLARiTy) project, which seeks to reduce the persistently high uncertainties in land carbon flux estimates and will include the development of new LUH products built upon high resolution remote sensing data to inform historical forest disturbances and areas of forest plantations.