North American climate in CMIP5 experiments: Part III: Assessment of twenty-first-century projections

In part III of a three-part study onNorthAmerican climate in phase 5 of theCoupledModel Intercomparison Project (CMIP5)models, the authors examine projections of twenty-first-century climate in the representative concentration pathway 8.5 (RCP8.5) emission experiments. This paper summarizes and synthesizes results from several coordinated studies by the authors. Aspects of North American climate change that are examined include changes in continental-scale temperature and the hydrologic cycle, extremes events, and storm tracks, as well as regionalmanifestations of these climate variables. The authors also examine changes in the eastern North Pacific and NorthAtlantic tropical cyclone activity and NorthAmerican intraseasonal to decadal variability, including changes in teleconnections to other regions of the globe. Projected changes are generally consistentwith those previously published forCMIP3, althoughCMIP5model projections differ importantly from those of CMIP3 in some aspects, including CMIP5 model agreement on increased central California precipitation. The paper also highlights uncertainties and limitations based on current results as priorities for further research. Althoughmany projected changes inNorth American climate are consistent across CMIP5 models, substantial intermodel disagreement exists in other aspects. Areas of disagreement include projections of changes in snow water equivalent on a regional basis, summerArctic sea ice extent, themagnitude and sign of regional precipitation changes, extreme heat events across the northern United States, and Atlantic and east Pacific tropical cyclone activity.