Climate change pressures for the conterminous United States: plant hardiness zones, heat zones, growing degree days, and cumulative drought severity

Evaluating multiple signals of climate change across the conterminous United States during three 30-year periods (2010–2039, 2040–2069, 2070–2099) during this century to a baseline period (1980–2009) emphasizes potential changes for growing degree days (GDD), plant hardiness zones (PHZ), heat zones (HeatZone), and cumulative drought severity (CDSI). These indices were derived using the CCSM4 and GFDL CM3 models under the representative concentration pathways 4.5 and 8.5, respectively, and included in Matthews et al. (2018). Daily temperature was downscaled by Maurer et al. (2007) at a 1/8 degree grid scale and used to obtain growing degree days, plant hardiness zones, and heat zones. Monthly precipitation and temperature downscaled to 30 arc-seconds (~800 meters) by Daly et al. (2008) for the period 1980–2015 and Thrasher et al. (2013) for the period 2016–2099, were aggregated to a 10 square kilometer grid and used to calculate a self-calibrated palmer drought severity index that was then aggregated into 30-year cumulative drought severity index values. Each of these indices provides unique information about plant health related to changes in climatic conditions that influence establishment, growth, and survival. These data and the calculated changes are provided as 13 (CDSI) or 14 (GDD, HeatZone, PHZ) individual IMG files for each index to assist with management planning and decision making into the future. For each of the four indices the following are included: one [two for nonCDSI] baseline file (1980–2009), three files representing 30-year periods for the scenario CCSM4 under RCP 4.5 along with three files of changes, and three files representing 30-year periods for the scenario GFDL CM3 under RCP 8.5 along with three files of changes.Forest managers planning for potential changes in precipitation, temperatures, and extreme events during the later parts of this century need information on how conditions are likely to change. The Research Map NRS-9 (Matthews et al. 2018), provides maps and regional summaries for four climatic indices across the conterminous United States that provide information on stressors related to tree establishment, growth, and survival. These climate data will support user specific evaluations and analyses.*These data are also available as a story map: https://usfs.maps.arcgis.com/apps/MapSeries/index.html?appid=96088b1c086a4b39b3a75d0fd97a4c40