Hot Enough for You? A Spatial Exploratory and Inferential Analysis of North American Climate-Change Projections

Climate models have become the primary tools for scientists to project climate change into the future and to understand its potential impact. Continental-scale General Circulation Models (GCMs) oversimplify the regional climate processes and geophysical features such as topography and land cover. Since the consequences of local/regional climate change are particularly relevant to natural-resource management and environmental-policy decisions, Regional Climate Models (RCMs) have been developed to produce high-resolution outputs on scales of 50 km and smaller. RCMs can simulate three-hourly “weather” over long time periods and generate a vast array of outputs, from which long-run averages are commonly used as a summary of how a climate model approximates a region’s climate. With anthropogenic forcings incorporated, RCMS provide a means to assess a combination of natural and anthropogenic influences on climate variability. The North American Regional Climate Change Assessment Program (NARCCAP) ran regional Climate Models (RCMs) 60 years into the future for 11,760 regions in North America, each of which is approximately 50 km × 50 km in area. Using the 94,080 temperature changes projected to 2070 for all regions, for two RCMs, and for the four seasons, both an exploratory and an inferential spatial analysis is presented; the inferential analysis is based on a Bayesian hierarchical model. Videos show regions of North America that attain or exceed temperature-change thresholds as a function of increasing threshold. The preponderance of our results throughout all regions of North America is one of warming by 2070, usually more (and sometimes much more) than 2◦C.