Climate Scenarios and Models Used For Developing the 2005 Pacific Northwest Climate Change Scenarios

Climate Scenarios

As part of the global effort to quantify future changes in climate, the Intergovernmental Panel on Climate Change (IPCC) has developed different scenarios of change in greenhouse gas and sulfate aerosol emissions for use in global climate modeling efforts. These scenarios are grouped in four categories, or storylines, based on different assumptions about demographic, social, economic, technological, and environmental change.

The CIG chose two scenario families for its most recent update of the Pacific Northwest climate change scenarios:

  • A2 Scenario Family. The A2 scenario family lies near the upper limit of future greenhouse gas emissions as projected in different emissions scenarios, particularly beyond 2050. The A2 scenario assumes continuously increasing population growth, slower adoption of non-fossil fuel sources, and slower technological change than other scenarios.
  • B1 Scenario Family. The B1 scenario family lies near the lower limit of projected changes in greenhouse gas emissions. The B1 scenario assumes global population growth peaks by mid-century and then declines, a rapid economic shift towards service and information economies, and the introduction of clean and resource-efficient technologies.

Both scenario families are considered equally probable. For more information on these and other scenario families, please see the IPCC's Special Report on Emissions Scenarios (2000).

Climate Models

The Climate Impacts Group has analyzed the climate response for the Pacific Northwest simulated by several climate models. These simulations were prepared by climate modeling centers worldwide for the Fourth IPCC Assessment (also referred to as AR4). For consistency with prior CIG work, we include the current versions of models used previously: HadCM3, ECHAM5, CCSM3, and PCM1 (CCSM3 is the successor to both the NCAR CSM and DOE PCM). To these we added five additional models to better represent the range of models participating in AR4. These are: CNRM_CM3, CSIRO_MK3 Miroc_3.2, IPSL_CM4, CGCM_3.1, and GISS_ER.


NCAR (National Center for Atmospheric Research, Boulder, CO, USA)

CCSM3.0, version
beta19 (2004):
atmosphere: CAM3.0,
ocean: POP1.4.3
(modified), gx1v3
sea ice: CSIM5.0, T85
land: CLM3.0, gx1v3 Collins, W.D., et al., 2005: The Community Climate System Model, Version 3 Journal of Climate, Main website:
CGCM_3.1 CCCma (Canadian
Centre for Climate
Modeling and
Analysis, Victoria, BC, Canada)
CGCM3.1 (2004):
atmosphere: AGCM3
(GCM13d, T47L31)
ocean: CCCMA
Greg Flato
National de Recherches
Toulouse, France)
CNRM-CM3 (2004):
atmosphere: Arpege-
Climat v3 (T42L45, cy
ocean: OPA8.1
sea ice: Gelato 3.10
river routing: TRIP,, jeanfrancois.
Atmospheric Research, Melbourne, Australia)
CSIRO Mk3.0 (2000):
atmosphere: spectral
ocean: MOM2.2
Mark Collier
Martin Dix (,
Tony Hirst
Model described by Gordon et al. The CSIRO Mk3 Climate System Model, 2002,
ECHAM5 MPI (Max Planck
Institute for
Meteorology, Hamburg,
ECHAM5/MPIOM (2004):
atmosphere: ECHAM5
ocean: OM (1x1L41)
sea ice: ECHAM5
Joerg Wegner
ECHAM5: E. Roeckner et. all, 2003, The atmospheric general circulation model ECHAM5 Report No. 349OM: Marsland et. all, 2003, The Max-Planck-Institute global ocean/sea ice model with orthogonal curvilinear coordinates Ocean Modell., 5, 91-127.OM: Haak, H. et. all, 2003: Formation and propagation of great salinity anomalies, Geophys. Research Letters, 30, 1473,10.1029/2003GL17065.
GISS_ER NASA/GISS (Goddard Institute for Space Studies) New York, NY
E3Af8aoM20A Kenneth Lo
HadCM3 Met Office (Exeter,
Devon, EX1 3PB, UK)

HadCM3 (1998):
atmosphere: (2.5 x 3.75)
ocean: (1.25 x 1.25)
sea ice: land:



Gordon, C., C. Cooper, C.A. Senior, H.T. Banks, J.M. Gregory, T.C. Johns, J.F.B. Mitchell and R.A. Wood, 2000. The simulation of SST, sea ice
extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments. Clim. Dyn., 16, 147-168. Johns, T.C., R.E. Carnell, J.F. Crossley, J.M. Gregory, J.F.B. Mitchell, C.A. Senior, S.F.B. Tett and R.A. Wood, 1997. The Second Hadley Centre Coupled Ocean-Atmosphere GCM: Model Description, Spinup and Validation. Clim. Dyn. 13, 103-134.
IPSL_CM4 IPSL (Institute Pierre Simon Laplace, Paris, France)
IPSL-CM4_v1 Sebastien Denvil,
(Center for Climate
System Research,
Tokyo, Japan /
National Institute for Environmental Studies, Ibaraki, Japan / Frontier Research Center for Global Change, Kanagawa, Japan)
MIROC3.2 (2004):
atmosphere: AGCM
(AGCM5.7b, T42 L20)
ocean & sea ice: COCO (COCO3.3, 256x192 L44) land: MATSIRO (T42)
Toru Nozawa
K-1 Coupled GCM Description (K-1 Technical Report No.1), in preparation
PCM1 NCAR (National
Center for Atmospheric Research, Boulder, CO, USA)

Parallel Climate Model
(PCM) version 1.1,
(2000): atm :
CCM3.6.6, (modified),
T42L18 ocn : POP1.0
(modified) Washington, W.M.,, 2000: Parallel climate model (PCM) control and transient simulations. Climate Dynamics, Volume 16 Issue 10/11 (2000) pp 755-774
Main website: