addressing climate change adaptation in regional transportation plans
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addressing climate change adaptation in regional transportation plans

addressing climate change adaptation in regional transportation plans addressing climate change adaptation in regional transportation plans

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11.07.2015 Views

Addressing Climate Change Adaptation in Regional Transportation PlansA Guide for California MPOs and RTPAsSummer average temperatures will increase more quickly than winteraverage temperatures.Average inland areas are likely to increase more quickly than coastal regions.Extreme heat events will become more common, last longer, and cover largerareas.Temperature changes over the next 30 to 40 years are already largelydetermined by past emissions. By 2050, temperatures are projected toincrease by an additional 1.8 to 5.4°F, regardless of future emissions.After 2050, temperature projections diverge for different emission scenarios.By 2100, the models project temperature increases between 3.6 to 9°F.PrecipitationProjected changes in precipitation are less clear cut than for temperature. Theseasonal pattern of cool and wet winters and hot and dry summers, typical of aMediterranean climate, is likely to continue. However, the amount ofprecipitation is likely to change, but where and how much rain and snowfalldiffers with both model and emission scenario. Based on Cayan et al. (2012), theprojections suggest the followingThe majority of models suggest drier conditions by mid-century (5 to8 percent less rainfall) with drier conditions persisting through the end of thecentury (9 to 12 percent less annual rainfall);More precipitation will fall as rain rather than as snow, with importantimplications for water resources;Higher temperatures hasten snowmelt and increase evaporation, which willmake for a generally drier climate; andRainfall and meltwater will run off earlier in the year.Sea-Level RiseSea level has been measured at the Presidio tide gauge in San Francisco since1854, which has recorded a rise in relative sea level of 7.6 inches per century inthe last 100 years (NRC, 2012). Rates of relative sea-level rise vary along thecoast in relation to vertical land movement: the observed rise per century is8.0 inches in San Diego, 3.3 inches in Los Angeles, and 2.7 inches in Port SanLuis; and is falling in Crescent City at a rate of 2.9 inches per century (NRC 2012,Table 4.6). Present sea-level rise projections suggest that global sea levels in the21 st century can be expected to be much higher, which will result in higher ratesof relative sea-level rise. These projections are summarized in the State ofCalifornia Sea-Level Rise Interim Guidance Document (OPC, 2010); and have beenincorporated into the Caltrans Guidance on Incorporating Sea-Level Rise (Caltrans2011):3-4 Cambridge Systematics, Inc.

Addressing Climate Change Adaptation in Regional Transportation PlansA Guide for California MPOs and RTPAsUp to 2050, the models show strong agreement and there is little variationbetween emission scenarios. After 2050 the projected global sea level variesby emission scenario.By 2050, the models show strong agreement for global sea-level rise with anaverage of 14 inches and a range of 10 to 17 inches higher than the sea level in2000.Table 3.1Year20702100Sea-Level Rise ProjectionsEmissionsAverage of Models(Inches)Range of Models(Inches)Low 23 17-27Medium 24 18-29High 27 20-32Low 40 31-50Medium 47 37-60High 55 43-69Source: OPC, 2010, presented in OPC, 2011.The recent sea-level rise publication from the NRC titled Sea-Level Rise for theCoasts of California, Oregon, and Washington: Past, Present, and Future (NRC 2012)revises some of the projections included in the OPC report and Caltransguidance. Caltrans is working with other state agencies to determine specificsea-level rise values to incorporate into future planning and design documents.As new state guidance becomes available it will be important to incorporate thatinformation into future planning assessments and update Caltrans guidance, asappropriate.Extreme EventsGradual changes in average temperature, precipitation and sea level aredescribed above. However, it is likely that the State will face a growing numberof climate change-related extreme events, such as heat waves, wildfires,droughts, and floods (Mastrandrea et al., 2009).Significant increases in the frequency and magnitude of both maximum andminimum temperature extremes are possible in many areas. It is projectedthere will be a tenfold increase in the frequency of extreme temperaturescurrently estimated to occur once every 100 years, even with moderateemissions. Under higher emissions, these 100-year temperature extremes areprojected to occur close to annually in most regions.Freezing events are projected to become less frequent even in locations wherethey are currently an annual event. Over large portions of the State, freezingevents may occur once every 10 years or less by the end of the 21 st century.Cambridge Systematics, Inc. 3-5

Address<strong>in</strong>g Climate Change Adaptation <strong>in</strong> Regional Transportation PlansA Guide for California MPOs and RTPAsUp to 2050, the models show strong agreement and there is little variationbetween emission scenarios. After 2050 the projected global sea level variesby emission scenario.By 2050, the models show strong agreement for global sea-level rise with anaverage of 14 <strong>in</strong>ches and a range of 10 to 17 <strong>in</strong>ches higher than the sea level <strong>in</strong>2000.Table 3.1Year20702100Sea-Level Rise ProjectionsEmissionsAverage of Models(Inches)Range of Models(Inches)Low 23 17-27Medium 24 18-29High 27 20-32Low 40 31-50Medium 47 37-60High 55 43-69Source: OPC, 2010, presented <strong>in</strong> OPC, 2011.The recent sea-level rise publication from the NRC titled Sea-Level Rise for theCoasts of California, Oregon, and Wash<strong>in</strong>gton: Past, Present, and Future (NRC 2012)revises some of the projections <strong>in</strong>cluded <strong>in</strong> the OPC report and Caltransguidance. Caltrans is work<strong>in</strong>g with other state agencies to determ<strong>in</strong>e specificsea-level rise values to <strong>in</strong>corporate <strong>in</strong>to future plann<strong>in</strong>g and design documents.As new state guidance becomes available it will be important to <strong>in</strong>corporate that<strong>in</strong>formation <strong>in</strong>to future plann<strong>in</strong>g assessments and update Caltrans guidance, asappropriate.Extreme EventsGradual <strong>change</strong>s <strong>in</strong> average temperature, precipitation and sea level aredescribed above. However, it is likely that the State will face a grow<strong>in</strong>g numberof <strong>climate</strong> <strong>change</strong>-related extreme events, such as heat waves, wildfires,droughts, and floods (Mastrandrea et al., 2009).Significant <strong>in</strong>creases <strong>in</strong> the frequency and magnitude of both maximum andm<strong>in</strong>imum temperature extremes are possible <strong>in</strong> many areas. It is projectedthere will be a tenfold <strong>in</strong>crease <strong>in</strong> the frequency of extreme temperaturescurrently estimated to occur once every 100 years, even with moderateemissions. Under higher emissions, these 100-year temperature extremes areprojected to occur close to annually <strong>in</strong> most regions.Freez<strong>in</strong>g events are projected to become less frequent even <strong>in</strong> locations wherethey are currently an annual event. Over large portions of the State, freez<strong>in</strong>gevents may occur once every 10 years or less by the end of the 21 st century.Cambridge Systematics, Inc. 3-5

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