Applying IPCC Representative Concentration Pathway (RCP) land-use projections in a regional assessment of land-use change in the conterminous United States.

The Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (RCPs) include global land-use change projections for four global emissions scenarios. These projections are potentially useful for driving regional-scale models needed for informing land-use and management interactions. Here, we applied global gridded RCP land-use projections within a regional-scale state-and-transition simulation model (STSM) projecting land-use change in the conterminous United States. First, we cross-walked RCP land-use transition classes to land-use classes more relevant for modeling at the regional scale. Coarse grid RCP land-use transition values were then downscaled to EPA Level III ecoregion boundaries using historical land-use transition data from the USGS Land Cover Trends (LCT) dataset. Downscaled transitions were aggregated to the ecoregion level. Ecoregions were chosen because they represent areas with consistent land-use patterns that have proven useful for studying land-use and management interactions. Ecoregion-level RCP projections were applied in a state-and-transition simulation model (STSM) projecting land-use change between 2005 and 2100 at the 1-km scale. Resulting RCP-based STSM projections were compared to STSM projections created using scenario projections from the Special Report on Emissions Scenarios (SRES) and the USGS LCT dataset. While most land-use trajectories appear plausible, some transitions such as forest harvest are unreasonable in the context of historical land-use patterns and the socio-economic drivers of change outlined for each scenario. This effort provides a method for using the RCP land-use projections in a wide range of regional scale models. However, further investigation is needed into the performance of RCP land-use projections at the regional scale.