Climate change scenarios for the California region
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Resource Abstract:
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°C under the lower emissions
B1 scenario in the less responsive PCM1 to +4.5°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 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
Title Climate change scenarios for the California region