The development of a high-resolution global land use projection downscaling model

Global gridded land use projection data is essential for the investigation of various research topics in global environmental change. Such information is commonly provided by various integrated assessment models (IAMs) at a relatively coarse resolution. For example, the Land Use Harmonization 2 (LUH2) provided future global land use data at 0.25-degree for CMIP 6. However, the demand for higher resolution land use projection data has been increasing in recent years for more granular analysis of various topics. The Asia-pacific Integrated Model (AIM), which is a widely known IAMs for climate policy study, could so far provide global gridded land use data at 0.5-degree resolution under the SSP-RCP scenario framework. In this study, I constructed a downscaling framework for the AIM land use model system, that combines an empirical land use change model and a cross-entropy minimization method and aimed to downscale land use projection from half-degree to 5 arcminutes or even higher resolution. The empirical land use change model is estimated by multinominal logit regression method with historical data from 1995 to 2015, which allows the land use change driven by various biophysical and socio-economic factors and provides prior land use distribution information for the cross-entropy minimization process. Validation for the period of 2015 to 2020 showed the effectiveness of the downscaling model. This newly developed downscaling model could provide high-resolution gridded land use projection information for global environmental change research community.