You are here

Climate change scenarios for the California region

TitleClimate change scenarios for the California region
Publication TypeManual Entry
AuthorsCayan, Daniel R., Edwin P. Maurer, Michael D. Dettinger, Mary Tyree, and Katharine Hayhoe
Date Published{MAR}

{To investigate possible future climate changes in California, a set of climate change model simulations was selected and evaluated. From the IPCC Fourth Assessment, simulations of twenty-first century climates under a B1 (low emissions) and an A2 (a medium-high emissions) emissions scenarios were evaluated, along with occasional comparisons to the A1fi (high emissions) scenario. The climate models whose simulations were the focus of the present study were from the Parallel Climate Model (PCM1) from NCAR and DOE, and the NOAA Geophysical Fluid Dynamics Laboratory CM2.1 model (GFDL). These emission scenarios and attendant climate simulations are not ``predictions,{''} but rather are a purposely diverse set of examples from among the many plausible climate sequences that might affect California in the next century. Temperatures over California warm significantly during the twenty-first century in each simulation, with end-of-century temperature increases from approximately +1.5 degrees C under the lower emissions B1 scenario in the less responsive PCM1 to +4.5 degrees C in the higher emissions A2 scenario within the more responsive GFDL model. Three of the simulations (all except the B1 scenario in PCM1) exhibit more warming in summer than in winter. In all of the simulations, most precipitation continues to occur in winter. Relatively small (less than similar to 10%) changes in overall precipitation are projected. The California landscape is complex and requires that model information be parsed out onto finer scales than GCMs presently offer. When downscaled to its mountainous terrain, warming has a profound influence on California snow accumulations, with snow losses that increase with warming. Consequently, snow losses are most severe in projections by the more responsive model in response to the highest emissions.}

Citation Key1102
Community Notes

how climate models were selected

"Models selected for attention here also were required to produce a realistic simulation of aspects of California’s recent historical climate particularly the distribution of monthly temperatures and the strong seasonal cycle of precipitation that exists in the region. In addition, models selected were required to contain realistic representations of some regional features, such as the spatial structure of precipitation. Because the observed California climate has exhibited considerable natural variability at seasonal to interdecadal time scales, the historical simulations by the climate models were required to contain variability that resembles that from observations at these short period climatic time scales."

Models were also chosen based on their sensitivity to GHG scenarios

The paper provides a nice template (table) for displaying projected changes based on the model, scenario, season, etc...

The GCMs were used for broad scale evaluation in determining which models should be used, but then they used Maurer's1 bias-corrected and downscaled data for streamflow forecasting.


Projects that used this resource: 

Climate Science Tags

Climate Impacts Tags

Impact by Sector: 
Specific Climate-Related Application: