Letter

Climatic Change

, Volume 120, Issue 4, pp 965-975

Open Access This content is freely available online to anyone, anywhere at any time.

Climate change projections of the North American Regional Climate Change Assessment Program (NARCCAP)

  • L. O. MearnsAffiliated withIMAGe, National Center for Atmospheric Research Email author 
  • , S. SainAffiliated withIMAGe, National Center for Atmospheric Research
  • , L. R. LeungAffiliated withPacific Northwest National Laboratory
  • , M. S. BukovskyAffiliated withIMAGe, National Center for Atmospheric Research
  • , S. McGinnisAffiliated withIMAGe, National Center for Atmospheric Research
  • , S. BinerAffiliated withOuranos
  • , D. CayaAffiliated withOuranos
  • , R. W. ArrittAffiliated withDepartment of Agronomy, Iowa State University
  • , W. GutowskiAffiliated withDepartment of Agronomy, Iowa State University
    • , E. TakleAffiliated withDepartment of Agronomy, Iowa State University
    • , M. SnyderAffiliated withDepartment of Earth Sciences, University of California Santa Cruz
    • , R. G. JonesAffiliated withUK Met Office Hadley Center
    • , A. M. B. NunesAffiliated withDepartment of Meteorology, Institute of Geosciences (IGEO) - CCMN, Federal University of Rio de Janeiro (UFRJ)Rio de Janeiro
    • , S. TuckerAffiliated withUK Met Office Hadley Center
    • , D. HerzmannAffiliated withDepartment of Agronomy, Iowa State University
    • , L. McDanielAffiliated withIMAGe, National Center for Atmospheric Research
    • , L. SloanAffiliated withDepartment of Earth Sciences, University of California Santa Cruz

Abstract

We investigate major results of the NARCCAP multiple regional climate model (RCM) experiments driven by multiple global climate models (GCMs) regarding climate change for seasonal temperature and precipitation over North America. We focus on two major questions: How do the RCM simulated climate changes differ from those of the parent GCMs and thus affect our perception of climate change over North America, and how important are the relative contributions of RCMs and GCMs to the uncertainty (variance explained) for different seasons and variables? The RCMs tend to produce stronger climate changes for precipitation: larger increases in the northern part of the domain in winter and greater decreases across a swath of the central part in summer, compared to the four GCMs driving the regional models as well as to the full set of CMIP3 GCM results. We pose some possible process-level mechanisms for the difference in intensity of change, particularly for summer. Detailed process-level studies will be necessary to establish mechanisms and credibility of these results. The GCMs explain more variance for winter temperature and the RCMs for summer temperature. The same is true for precipitation patterns. Thus, we recommend that future RCM-GCM experiments over this region include a balanced number of GCMs and RCMs.