The Coupled-Model Intercomparison Project Phase 5 (CMIP5) set of climate model simulations are used as the foundational material for climate scenarios. The Localized Constructed Analogs (LOCA) dataset is a new statistically-downscaled dataset derived from the CMIP5 simulations. The LOCA data include 32 CMIP5 models covering the period 1950–2100, including the historical period of 1950–2005 and a high emissions scenario and a low emissions scenario for 2006–2100. The LOCA data include maximum temperature, minimum temperature, and precipitation at a daily resolution and at 1/16th degree spatial resolution. The LOCA data cover the continental U.S., southern Canada, and northern Mexico.
A large number of derived climate variables have been calculated from the daily LOCA data. Three maps of the future change relative to the reference period of 1976–2005 are available for each scenario. These include the early 21st Century (2016–2045), mid 21st Century (2036–2065), and late 21st Century (2070–2099). For the first time in a U.S. National Assessment, model weighting was used in the calculation of multi-model mean. The model weights were derived by comparing model simulations of the historical period with observations for 12 observed climate variables, as described in the Climate Science Special Report and following the methodology of Sanderson et al. (Sanderson, B.M., R. Knutti, and P. Caldwell, 2015: A Representative Democracy to Reduce Interdependency in a Multimodel Ensemble. Journal of Climate, 28, 5171–5194. http://dx.doi.org/10.1175/JCLI-D-14-00362.1).
In addition to the multi-model mean maps, a set of maps were developed that represent the high end of the distribution, useful for risk-based framing analyses. Specifically, the 3 models with the largest warming for the LOCA domain at the end of 21st Century under the high emissions scenario were identified. For all of the temperature variables, the arithmetic mean of those 3 models was calculated. Likewise, the 3 models with the largest change in the annual maximum 1-day precipitation averaged over the LOCA domain at the end of the 21st Century under a high emissions scenario were identified. For all of the precipitation variables, the arithmetic mean of those 3 models was calculated. Maps of these calculations were developed.
Several maps in the Climate Science Special Report show projections for North America, including Alaska and Hawaii, and for other variables. These maps are provided here for the convenience of authors and other users.
State climate summaries project were recently completed as a NOAA contribution to the National Climate Assessment. These summaries cover historical climate variations and trends, future climate model projections of climate conditions during the 21st century, and past and future conditions of sea level and coastal flooding.