Climate and Energy Action Plan (CEAP)

CLIMATE TRENDS & PRO JECTIONS | CITY OF ASHLAND, OREGON | FINAL REPORT | 13 Extreme Warm Temperature Extreme warm temperature projectio ns are examined using the hottest day of the year , the warm spell duration index , number of days above 100°F, number of days above 110°F, and number of nights above 60°F . Hottest Day of Year The range of future changes in t he temperature of the hottest day of the year in Ashland is 4°F to 10°F for the 2050s and 5° F to 14°F for the 2080s ( see Table 2); this is the range across all models and both emissions scenarios . The multi -model mean projects an increase of about 12°F by the 2080s under the high emissions scenario compared to the histori c baseline (1950 -2005) ( see Figure 4). Figure 4. Temperature of the hottest day of year projections for Ashland as simulated by 18 downscaled global climate models for the historical period (1950 -2005) and future (2006 -2099) under a low (RCP4.5) and high (RCP8.5) greenhouse gas emissions scenario. Solid line and shading depicts the 18 -model mean and range, respecti vely. The multi -model mean differences for the 2050s (2040 -2069 average) and 2080s (2070 -2099 average) compared to the historical baseline (1950 -2005) are displayed. Warm Spell Duration Index A warm spell is defined as at least six consecutive days where each day is above the 90th percentile of temperature for that calendar date in the historical baseline (1950 -2005 average). Future warm spells are still determined using the 90th percentile temperature threshold from the historical baseline. The warm spel l duration index counts the number of days per year that occur within such warm spells. Projections indicate the number of warm spell days per year in Ashland is likely to increase by between 11 to 66 days by the 2050s and 18 to 136 days by the 2080s ( refer back to Table 2); this is the range of future changes across all models and both emissions scenarios . The multi -model mean projects 89 more warm spell days by the 2080s under the high emissions scenario compared to the histori c baseline (1950 -2005) ( see Figure 5). Ashland Hottest Da y of Y ear Pr ojections°F Histor ical Low (RCP4.5) High (RCP8.5) 2050s +6 °F2050s +7 °F 2080s +7 °F2080s +12 °F 9095100105110115120125 1950 1970 1990 2010 2030 2050 2070 2090