Climate scenarios and projections

The 2020 RPA Assessment includes climate change as a driver affecting natural resources on forests and rangelands in the United States. This publication describes the process used to select the scenarios, climate models, and climate projections that will be used to project renewable resource conditions 50 years into the future. Downscaled climate data selected are the MACAv2-METDATA developed by Abatzoglou and others at the University of Idaho. The dataset covers the conterminous United States at a grid size of approximately 4 km (1/24 degree) on a side. The two selected scenarios are the Representative Concentration Pathways (RCPs) 4.5 and 8.5. Three criteria were used to select the climate models: (1) identification and elimination of poor performing models based on historical climate projections, (2) restriction of selection to only one model from a modeling institution, and (3) selection of a climate model that could provide projections for both the RCP 4.5 and RCP 8.5 scenarios. Climate models and projections were selected to capture a range of future climates at the conterminous scale: least warm projection, hottest projection, driest projection, and wettest projection, and one projection that reflected the middle of these ranges. The core model projections to be used in the 2020 RPA Assessment under RCP 4.5 and RCP 8.5 are: Least Warm-MRI-CGCM3; Hot-HadGEM2-ES; Dry-IPSL-CM5A-MR; Wet-CNRM-CM5; Middle-NorESM1-M. Future climates at mid-century (2041-2070) are summarized for the conterminous United States. The data are available at the USDA Forest Service Research and Development Data Archive.