addressing climate change adaptation in regional transportation plans

Cal-Adapt ProjectionsTable 33. Summary of Cal-Adapt Climate Projections for the Southeast Sierra RegionEffectRangesTemperatureChange,1990-2100PrecipitationHeat WaveSnowpackWildfire RiskJanuary increase in average temperatures: 1.5°F to 2.5°F by 2050 and 5°F to 10°F by 2100.July increase in average temperatures: 3°F to 5°F by 2050 and 8°F to 10°F(Modeled high temperatures; average of all models; high carbon emissions scenario)Potential precipitation decline is between 0 and 4 inches by 2050 and 1 and15 inches by 2100. The range varies widely depending on location. Someareas receive less than 6 inches annually, with projected reductions bringingtotals under 4 inches by 2090. In other areas, total rainfall exceeds 45inches per year and is projected to decrease by roughly 15 inches by 2090.(CCSM3 climate model; high carbon emissions scenario)There is a lot of variation in heat wave threshold in this region. To the north a heat waveis five days over temperatures in the 80s. To the south, a heat wave is five days overtemperatures as high as 115°F. By 2050, there will be 2 to 3 more heat waves per year,increasing up to over 14 to 16 per year by 2100.Snowpack levels are projected to decline dramaticallyby 2090 in some areas, with drops of over 50 percent.(CCSM3 climate model; high carbon emissions scenario)By 2085, wildfire risk is projected to increase substantially (up to 19.1times) over current levels in Alpine County and the northern part of MonoCounty. The rest of Mono County and all of Inyo County is projected tohave a wildfire risk between 1.1 to 4.8 times greater than current levels.(GFDL climate model; high carbon emissions scenario)[Public Interest Energy Research, 2011. Cal-Adapt. Retrieved from http://cal-adapt.org. Sierra Nevada Alliance, 2010.]Water SourcesThis climate region occupies the southern portion of the North Lahontanhydrologic region and the Mono and Inyo county portions of the South Lahontanhydrologic region. Groundwater meets over 65 percent of urban, agricultural, andenvironmental water demands in the South Lahontan. Locally developed surfacewater accounts for 90 percent of water consumption in the region (DWR,2009). Much of the surface water, however, is not available locally because ofwater appropriation rights that lay claim to the region’s water resources. Forexample, Inyo County has a joint agreement with the Los Angeles Departmentof Water and Power for groundwater pumping and surface water managementin the Owens Valley. The Owens Valley Basin has an estimated capacity of 30 to35 million acre-feet (DWR, 2009). Replenishment of the basin comes primarilyfrom percolation of the surrounding mountains’ stream flow. Major water bodiesinclude Mono Lake, June Lake, Grant Lake, and Lundy Reservoir (Mono CountyCommunity Development Department, Planning Division, 2007).APG: UNDERSTANDING REGIONAL CHARACTERISTICS PAGE 81