addressing climate change adaptation in regional transportation plans

Cal-Adapt ProjectionsTable 5. Summary of Cal-Adapt Climate Projections for the North RegionEffectTemperatureChange, 1990-2100RangesJanuary average temperature increase of 0.5°F to 4°F by 2050 and 3°F to 6°F by 2100.July average temperature increase 3°F to 5.5°F by 2050 and 8°F to 10°F by 2100, with largertemperature increases in the mountainous areas in the northeastern portion of the region.(Modeled high temperatures – average of all models; high carbon emissions scenario)PrecipitationHeat WaveSnowpackWildfire RiskAnnual precipitation is projected to decline by approximately an inch by 2050 and 2 inches by2100 for most of the region.(CCSM3 climate model; high carbon emissions scenario)Heat wave is defined as five days above a temperature between 89°F and 99°F dependingon location. By 2050 there is projected to be two to four more heat waves than 2010.Projected heat wave occurrence in 2100 is variable depending on location, between six and15 per year.March snowpack disappears by 2090 for most of the region with the exception of areas nearMt. Shasta.(CCSM3 climate model; high carbon emissions scenario)Substantial increases in the likelihood of wildfires are projected in most of the region,especially in Shasta and Siskiyou counties where risks may be multiplied 6 to 14 times by theend of the century.(GFDL climate model; high carbon emissions scenario)[Public Interest Energy Research, 2011. Cal-Adapt. Retrieved from http://cal-adapt.org]Water SourcesThe North region overlaps portions of the Sacramento River, NorthernLahontan, and North Coast hydrologic regions as defined by the CaliforniaDepartment of Water Resources (2009). Water supply relies on a mix ofimported, regional surface water and groundwater resources for meetinglocal demand. Overdraft and illegal diversions create challenges for resourcemanagement in some areas, contributing to concerns about the preservationof aquatic and riparian habitats (DWR, 2009). Most of Shasta County, thesoutheastern corner of Siskiyou County, the central portions of Modoc County,and the northwestern area of Lassen County are located in the SacramentoRiver hydrologic region. In this region there is heavy reliance on groundwaterand on the surface water conveyance systems that provide much of the Deltainflow. The easternmost parts of Modoc County and much of Lassen County arelocated in the North Lahontan hydrologic region (DWR, 2009). The Susan Riverdrains the North Lahontan area and serves as a critical source of water. TrinityCounty, much of Siskiyou County, and the northwestern portions of ModocAPG: UNDERSTANDING REGIONAL CHARACTERISTICS PAGE 22