addressing climate change adaptation in regional transportation plans

Cal-Adapt ProjectionsTable 9. Summary of Cal-Adapt Climate Projections for the Bay Area RegionEffectTemperatureChange, 1990-2100PrecipitationSea Level RiseHeat WaveFire RiskRangesJanuary: 4°F to 5°F increase in average temperaturesJuly: 5°F to 6°F increase in average temperatures(Modeled high temperatures – average of all models; high carbon emissions scenario)Precipitation varies widely in this region, with annual totals over 40 inches in northernSonoma County to roughly 15 inches in the eastern portions of Solano and Contra Costacounties. A moderate decline in annual rainfall, 1 to 3 inches by 2050 and 4 to 5 inches by2090, is projected throughout the region.(CCSM3 climate model; high carbon emissions scenario)By 2100, sea levels may rise up to 55 inches, posing considerable threats to coastal areasand particularly to low-lying areas adjacent to San Francisco Bay. The number of acresvulnerable to flooding is expected to increase 20 to 30 percent in most parts of the BayArea, with some areas projected for increases over 40 percent. Coastal areas are estimatedto experience an increase of approximately 15 percent in the acreage vulnerable to flooding.Along the coast, particularly to the south, heat wave is defined as five days over 72°F to 77°F;in other areas the threshold is in the mid- to upper 90s. Over most of the region a limitedincrease in the number of heat waves is expected by 2050 with only the eastern areasexpecting more than one or two more per year. By 2100, between six and 10 more heatwaves can be expected per year.There is little change in projected fire risk in this region, save for the slight increasesexpected in western Marin County.(GFDL climate model; high carbon emissions scenario)[Public Interest Energy Research, 2011. Cal-Adapt. Retrieved from http://cal-adapt.org]Water SourcesApproximately 70 percent of the water used in the region is imported, with another 15 percentsupplied via groundwater. The imported water comes from a variety of sources, including theRussian River (4 percent); the Delta (approximately 32 percent, via San Luis Reservoir, North BayAqueduct, Contra Costa Canal, South Bay Aqueduct); Lake Berryessa (5 percent); MokelumneRiver (25 percent); and Tuolumne River (33 percent). The vast majority of these water sources(e.g., Delta sources, Mokelumne River, Tuolumne River) originate in the Sierra Nevada, meaningthat climate change impacts on snowpack may have a dramatic impact on the Bay Area watersupply. Total reservoir storage capacity in the Bay Area is 746,000 acre-feet (DWR, 2009).Biophysical CharacteristicsThe Bay Area region is located in an area characterized by a Mediterranean climate, with warmersummer temperatures observed in the eastern portions of the region. San Francisco Bay andthe associated estuarine ecosystem sit at the center of the region and serve as the outlet forPAGE 29APG: UNDERSTANDING REGIONAL CHARACTERISTICS