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6 Summing Up T he charge to this committee was to review the current scientific understanding of climate change from the perspective of those changes of particular relevance for U.S. transportation, including the limits of current knowledge; to identify potential impacts on U.S. trans- portation infrastructure and operations; to consider adaptation options; and to offer recommendations on actions that can be taken to prepare for climate change and on needed research. In this final chapter, the commit- tee presents its consensus findings and recommendations in response to this charge, along with its principal supporting arguments. The commit- teeâs consensus position was informed by the five papers commissioned for this study; the 1-day conference held midway through the study to obtain the input of a broad range of transportation academicians and practitioners, climate scientists, and other experts; reviews of previous studies that examined the potential impacts of climate change on trans- portation, with a focus on adaptation strategies; numerous briefings on a wide range of relevant topics presented at committee meetings; and the committeeâs own expertise and judgment. The chapter is organized on the basis of a series of questions that guided the committeeâs thinking. WHICH CLIMATE CHANGES ARE MOST RELEVANT FOR U.S. TRANSPORTATION? Finding: The past several decades of historical regional climate patterns commonly used by transportation planners to guide their operations and investments may no longer be a reliable guide for future plans. In particular, future climate will include new classes (in terms of magnitude and frequency) of weather and climate 189
190 Potential Impacts of Climate Change on U.S. Transportation extremes, such as record rainfall and record heat waves, not expe- rienced in modern times as human-induced changes are superimposed on the climateâs natural variability. Transportation planners and engineers typically extrapolate from histori- cal weather and climate patterns in planning and designing infrastructure. The past will not be a good predictor of future conditions, however, as climate changes bring new weather patterns and climate extremes that exceed current experience. Projections of future climate are often depicted as gradual changes, such as the rise in global temperatures or in sea levels projected over this century. However, climate changes are unlikely to be experienced in such a smooth manner because human-induced changes will be amplified in some years by naturally fluctuating conditions, reflected in potentially sudden and dramatic changes at the regional or local level, where transportation infrastructure is located. Warming tem- peratures may trigger weather extremes and surprises, such as more rapid melting of the Arctic sea ice or more rapid rise in sea levels than is pro- jected by current climate models. On the basis of current knowledge, climate scientists have identified five climate changes of particular importance to U.S. transportation and estimated the probability of their occurrence during the 21st century: â¢ Increases in very hot days and heat waves (very likely),1 â¢ Increases in Arctic temperatures (virtually certain), â¢ Rising sea levels (virtually certain), â¢ Increases in intense precipitation events (very likely), and â¢ Increases in hurricane intensity (likely). HOW WILL CLIMATE CHANGE AFFECT U.S. TRANSPORTATION? Finding: Climate change will affect transportation primarily through increases in several types of weather and climate extremes, such as very hot days; intense precipitation events; intense hurri- 1 The Intergovernmental Panel on Climate Change (IPCC) (2007) Working Group I established the following terminology to describe uncertainty, that is, the probability of occurrence: virtually certain, >99 percent; extremely likely, >95 percent; very likely, >90 percent; likely, >66 percent; more likely than not, >50 percent; unlikely, <33 percent; very unlikely, <10 percent; extremely unlikely, <5 percent.
Summing Up 191 canes; drought; and rising sea levels, coupled with storm surges and land subsidence. The impacts will vary by mode of transporta- tion and region of the country, but they will be widespread and costly in both human and economic terms and will require signif- icant changes in the planning, design, construction, operation, and maintenance of transportation systems. Transportation infrastructure was designed for typical weather patterns and environmental conditions, reflecting local climate and incorporating assumptions about a reasonable range of temperatures and precipitation levels. It will be affected most by those climate changes that cause envi- ronmental conditions to extend outside the range for which the system was designed. Finding: Potentially, the greatest impact of climate change for North Americaâs transportation systems will be flooding of coastal roads, railways, transit systems, and runways because of global rising sea levels, coupled with storm surges and exacerbated in some locations by land subsidence. Fully 53 percent of the U.S. population now lives in counties with coastal regions, many among the most densely populated in the nation. If devel- opment pressures continue in vulnerable coastal areas, and there is every reason to believe they will, the impacts of climate change will be magni- fied as increasing numbers of people and businesses are placed in harmâs way, and the infrastructure is expanded or new infrastructure is built to accommodate the growth. The Atlantic and Gulf Coasts are particularly vulnerable because they have already experienced high levels of erosion, land subsidence, and loss of wetlands. Their vulnerability to the storm surges and wave action that accompany strong tropical storms was amply demonstrated during the 2005 hurricane season. Sea level rise and coastal flooding also pose risks for the East Coast, as well as the Pacific Northwest and parts of the California coast. The impacts of climate change will not be limited to coastal areas. For example, watersheds supplying water to the St. Lawrence Seaway and the Great Lakes, as well as the Upper Midwest river system, are likely to experience drier conditions, resulting in lower water levels and reduced capacity to ship agricultural and other bulk commodities, although a longer shipping season could offset some of the adverse economic
192 Potential Impacts of Climate Change on U.S. Transportation effects. Thawing permafrost in Alaska is already creating settlement and land subsidence problems for roads, rail lines, runways, and pipelines. Higher temperature extremes (mainly heat waves) in some U.S. regions could lead to more frequent buckling of pavements and misalignment of rail lines. More severe weather events with intense precipitation could increase the severity of extensive flooding events, such as the storms that plagued the Midwest during the 1993 flooding of the Mississippi and Missouri River system, the Chicago area in 1996, and the Houston region during Tropical Storm Allison in 2001. Flooding of a waterway system can knock out barge operations on the river itself, rail operations on rights-of-way adjacent to the river, and even highway approaches to bridges crossing flooded rivers. Not all climate change impacts will be negative. For example, the marine transportation sector could benefit from more open seas in the Arctic, creating new and shorter shipping routes and reducing transport time and costs. In cold regions, expected temperature rises, particularly decreases in very cold days and later onset of seasonal freezes and earlier onset of seasonal thaws, could mean reduced costs of snow and ice con- trol for departments of transportation and safer travel conditions for passenger vehicles and freight. Recommendation 1: Federal, state, and local governments, in collaboration with owners and operators of infrastructure, such as ports and airports, and private railroad and pipeline companies, should inventory critical transportation infra- structure in light of climate change projections to determine whether, when, and where projected climate changes in their regions might be consequential. Inventorying transportation assets essential to maintaining network per- formance to determine their potential vulnerability to projected climate changes is a sensible first step. Information about projected climate changes is currently available from climate scientists for large subconti- nental regionsâa scale more relevant than global projections for regional and local transportation infrastructure. Although such an inventory must be updated periodically as new scientific knowledge about climate change becomes available, inventorying is a relatively low-cost activity. Many of the tools needed for the purpose [e.g., geographic information systems (GIS)] are available. The inventorying process itself should help identify
Summing Up 193 with greater precision the data needed on transportation-relevant climate changes and encourage collaboration between transportation profession- als and climate scientists. HOW SHOULD TRANSPORTATION DECISION MAKERS RESPOND? Finding: Public authorities and officials at various governmental levels and executives of private companies are continually making short- and long-term investment decisions that have implications for how the transportation system will respond to climate change in the near and long terms. Transportation decision makers have an opportunity now to prepare for projected climate changes. Decisions made today, particularly those related to the redesign and retrofitting of existing or the location and design of new transportation infrastructure, will affect how well the system adapts to climate change far into the future. Many transportation facilities, such as bridges, large culverts, and rail and port facilities, are designed with long service lives and help shape development patterns that, once in place, are difficult to change. Thus, transportation planners and engineers should consider how projected climate changes in their regions might affect these facilities. Recommendation 2: State and local governments and private infrastructure providers should incorporate climate change into their long-term capital improvement plans, facility designs, maintenance practices, operations, and emergency response plans. Taking measures now to evaluate and protect the most vulnerable infra- structure should pay off by diminishing near-term maintenance expenditures and reducing the risk of catastrophic failure, with its toll on human life and disruption of economic activity. Such measures might include strengthening or elevating some coastal roads, rail lines, and bridges, particularly those that serve as evacuation routes, or upgrading parallel routes where they are available.2 In the longer term, relocation of 2 States in particularly vulnerable regions such as the Gulf Coast could consider securing and banking rights-of-way for alternative evacuation routes, should they prove necessary.
194 Potential Impacts of Climate Change on U.S. Transportation rights-of-way farther inland or installation of costly storm barrier systems to protect selected areas (e.g., parts of New York City or Miami) might be considered. Finding: The significant costs of redesigning and retrofitting trans- portation infrastructure to adapt to potential impacts of climate change suggest the need for more strategic, risk-based approaches to investment decisions. Designing transportation facilities to more robust standards to hedge against potentially negative impacts of climate change will produce much more costly designs that are likely to be unacceptable given limited budg- ets. More strategic and selective risk-based approaches are needed for determining appropriate design standards and investment priorities. Transportation professionals already take risk into account, particularly in designing facilities. For example, structures are designed to withstand certain wind speeds on the basis of probabilistic assessments of wind speed occurrence using historical data on wind speed frequency. Drainage requirements for many transportation facilities are sized to accommo- date the 100-year storm, a probabilistic assessment of storm frequency. Engineers also commonly incorporate safety factors into designs or design standards to account for unforeseen events or abnormal forces on structures. In general, however, transportation decision makers have a long way to go to take full advantage of quantitative, risk-based approaches that incorporate uncertainty and probabilistic assessments in making invest- ment and design decisions. Recommendation 3: Transportation planners and engineers should use more probabilistic investment analyses and design approaches that incorporate techniques for trading off the costs of making the infrastructure more robust against the economic costs of failure. At a more general level, these techniques could also be used to communicate these trade-offs to policy makers who make investment decisions and authorize funding. At present, the necessary data and certitude about projections of future cli- mate, particularly at the local and regional levels, are not available to permit a comprehensive probabilistic risk assessment and analysis. However, more
Summing Up 195 simplified approaches can be used by transportation planners and engi- neers to incorporate many of these risk assessment concepts into their planning and design. One model is the California Seismic Retrofit Program. Following the Loma Prieta earthquake in 1989, the California Department of Transportation developed a risk-based approach for ana- lyzing the vulnerability of highway bridges statewide to earthquakes and their criticality to the network to make it possible to determine investment priorities for retrofitting and replacement. The program established a higher performance standard for 750 structures to protect the investment in these major facilities and ensure that these vital transportation lifelines would remain in service after a major seismic event to provide access for emergency responders. The stateâs 11 major toll bridges were handled sep- arately because their complexity demanded a time-consuming dynamic analysis. For most other bridges, the standard was âno collapseâ under a maximum seismic event, consistent with the geographic location of the bridge. The objective was to avoid loss of life; however, some damage to a structure was acceptable as long as it remained intact and could be reopened for service soon after the event. Extending and incorporating such techniques to include climate change will require more complete data on the likelihood of climate- related hazards and their economic consequences. It will also necessitate continuing education of current planners and engineers and training of future professionals. Finally, educating policy makers to gain their support will entail communicating the information so that the trade-offs and investment priorities are clear. It may also require new eligibility criteria in funding programs, and new funding sources may also be necessary to make the investments identified by the application of these techniques. WHAT DATA AND DECISION SUPPORT TOOLS ARE NEEDED? Finding: Transportation professionals often lack sufficiently detailed information about expected climate changes and their timing to take appropriate action. Transportation decision makers note that one of the most difficult aspects of addressing climate change is obtaining the relevant information in the form they need for planning and design. This difficulty is not limited to the transportation sector. A recent National Research Council report (NRC
196 Potential Impacts of Climate Change on U.S. Transportation 2007) found that while the scientific understanding of climate change has made great progress, the use of that knowledge to support decision making and formulate mitigation and adaptation strategies is much less well devel- oped. Climate change is understood with greatest confidence as a global or continental phenomenon, while transportation planners as well as other decision makers need local and regional climate projections. They also need a better understanding of how projected climate changes, such as changes in temperature and precipitation, will affect the environment (e.g., soil moisture, runoff) in which the infrastructure is situated, which will vary from region to region. Climate projections themselves are presented by climate scientists as a portfolio of plausible scenarios and outcomes, which are continually refined and revised as new knowledge accumulates. Transportation planners need to have a better understanding of which sce- narios are most plausible for their regions and most significant for their operations and plans. Recommendation 4: The National Oceanic and Atmospheric Administration, the U.S. Department of Transportation (USDOT), the U.S. Geological Survey, and other relevant agencies should work together to institute a process for bet- ter communication among transportation professionals, climate scientists, and other relevant scientific disciplines, and establish a clearinghouse for transportation-relevant cli- mate change information. All professions should benefit from the collaboration. Transportation pro- fessionals would be encouraged to define with greater precision the climate data needed to improve transportation decisions, such as temperature and precipitation thresholds at finer-grained geographic scales or climate con- ditions that would create unacceptable performance outcomes. Climate scientists would be challenged to elaborate on the possibilities and limita- tions of projecting impacts of climate change at the levels of geographic specificity that are most useful for transportation planners. And hydrolo- gists and others would be challenged to consider how the environment would influence these effects and their impacts on transportation infra- structure. One promising approach might be for the federal government to support a number of pilot projects in which federal agencies would work closely with local transportation planners to include the full range of rele- vant climate information that could affect a specific project.
Summing Up 197 Finding: Better decision support tools are also needed to assist transportation decision makers. Recommendation 5: Ongoing and planned research at fed- eral and state agencies and universities that provide climate data and decision support tools should include the needs of transportation decision makers. For example, the research program of the USDOT Center for Climate Change and Environmental Forecasting could be charged with expanding its existing research program in this area and provided the necessary fund- ing. Needed tools include accurate digital elevation maps in coastal areas for forecasting the effects of flooding and storm surge heights; GIS that can be used to map the locations of critical infrastructure, overlaid with informa- tion on climate change effects (e.g., sea level rise, permafrost melt); greater use of scenarios that include climate change in the development of long- range regional transportation plans to pinpoint likely vulnerabilities (e.g., areas susceptible to sea level rise, aggravated by storm surge) and ways to address them; and better transportation network models for examining the systemwide effects of the loss of critical transportation infrastructure links. WHICH ADAPTATION STRATEGIES MAKE SENSE? Transportation decision makers have a wide range of adaptation options from which to choose in determining how best to adjust to climate change. One way to organize these options is around the timescales used by transportation professionals in their decision making. For example, operational decisions are typically focused on the short term and thus will be concerned mainly with near-term changes in weather and climate con- ditions. Decisions about rehabilitating or retrofitting infrastructure are made with a longer time horizon in mind. Such decisions will determine the performance of those assets with long service lives for many decades and thus should take longer-term climate projections into consideration so likely hazards can be assessed. Decisions about new infrastructure or major capacity additions involve the longest time frame because they will shape land use and development patterns for years to come and thus may require consideration of climate change projections that extend into the 22nd century. Other adaptation options, such as monitoring and use of technology or new organizational arrangements, cut across timescales and
198 Potential Impacts of Climate Change on U.S. Transportation offer adaptation options in their own right or ways to better incorporate climate change in transportation decision making. Operational Responses Finding: Projected increases in extreme weather and climate underscore the importance of emergency response plans in vul- nerable locations and require that transportation providers work more closely with weather forecasters and emergency planners and assume a greater role in evacuation planning and emergency response. U.S. transportation providers already address the impacts of weather on transportation system operations in a diverse range of climatic conditions. For example, snow and ice control accounts for about 40 percent of annual highway operating budgets in the northern U.S. states. Likewise, hurricane planning has become a major focus of transportation operations in the Gulf Coast states, where transportation providers are forging close rela- tionships with emergency responders to handle severe weather events. As climate changes induce new extremes (e.g., more intense storms, more intense precipitation), operational responses are likely to become more routine and proactive than todayâs approach of treating severe weather on an ad hoc, emergency basis. For example, if hurricanes increase in intensity, as is likely to be the case, establishment of evacuation routes and use of contraflow operations may become as commonplace as the current use of snow emergency routes in the Northeast and Midwest. More accurate and timely weather prediction and communication of storm warnings in real time to those potentially in harmâs way will become more important. Recommendation 6: Transportation agencies and service providers should build on the experience in those locations where transportation is well integrated into emergency response and evacuation plans. Following the events of September 11, 2001, and the experience with Hurricanes Katrina and Rita, coordination between state and local emergency managersâthe first responders in an emergencyâand transportation agencies and service providers improved, particularly in
Summing Up 199 those locations with recurring natural disasters, such as hurricanes. In some locations, transportation is represented at emergency operations centersâcommand posts that can be activated rapidly in an emergency. Transportation agencies and service providers are also working closely with weather forecasters and emergency response planners to convey their own lead-time requirements so they can provide the personnel and equipment necessary for evacuation and protect their own assets. Transportation agencies and service providers in locations where collab- oration is not as advanced should build on this experience. Monitoring and Use of Technology Finding: Greater use of technology would enable infrastructure providers to monitor climate changes and receive advance warn- ing of potential failures due to water levels and currents, wave action, winds, and temperatures exceeding what the infrastruc- ture was designed to withstand. Monitoring infrastructure conditions, particularly the impacts of weather and climate extremes, offers an alternative to preventive retrofitting or reconstruction of some facilities. It is also an activity that can begin imme- diately. In Alaska, which is experiencing more accelerated climate changes than the lower 48 states, the Alyeska Pipeline Company already monitors the right-of-way of the Trans-Alaska Pipeline System to spot land subsi- dence problems, particularly along the 800 miles of pipeline elevated on vertical supports. Alaskan engineers also closely monitor bridge supports, which are experiencing damage from earlier winter runoff and increased stream flow. In the future, sensors and other âsmartâ technologies could be embedded in the infrastructure to monitor changing climate conditions and impacts and provide warning when pressure or stress thresholds are being exceeded. Development of more heat-resistant materials could help protect pavements and some rail facilities, in particular, from the adverse impacts of projected temperature extremes. Recommendation 7: Federal and academic research programs should encourage the development and implementation of monitoring technologies that could provide advance warning of pending failures due to the effects of weather and climate extremes on major transportation facilities.
200 Potential Impacts of Climate Change on U.S. Transportation Advances in sensor technologies, computer processing, and communica- tions capabilities should provide a fertile field for the development of smart devices that can be used for monitoring changing climate condi- tions and communicating the results to the appropriate transportation infrastructure owners. Advances in material sciences should enable the development of new materials that can withstand climate extremes. Sharing of Best Practices Finding: The geographic extent of the United Statesâfrom Alaska to Florida and from Maine to Hawaiiâand its diversity of weather and climate conditions can provide a laboratory for identifying best practices and sharing information as the climate changes. As a result of climate change, many areas of the United States will expe- rience new climate-induced weather patterns. These changes, however, may not necessarily require the development of new operating and main- tenance strategies. The United States has a diverse climate, ranging from subtropical to arctic and from arid to wet, with several regions being sub- ject to temperature extremes and such events as blizzards, hurricanes, tornadoes, floods, wildfires, avalanches, and mudslides. As climate pat- terns change, transfer of best practices from one location to another will be essential. Recommendation 8: The American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration, the Association of American Railroads, the American Public Transportation Association, the American Association of Port Authorities, the Airport Operators Council, associations for oil and gas pipelines, and other relevant transportation professional and research organizations should develop a mechanism to encourage shar- ing of best practices for addressing the potential impacts of climate change. This effort should build on technology transfer mechanisms that already exist, such as AASHTOâs technology-sharing program. Technology should be defined broadly to include probabilistic decision-making tools, as well as monitoring technologies, new materials, and operating and mainte- nance strategies.
Summing Up 201 Design Changes Finding: Reevaluating, developing, and regularly updating design standards for transportation infrastructure to address the impacts of climate change will require a broad-based research and testing program and a substantial implementation effort. Operational responses are geared to addressing near-term impacts of climate change, but rehabilitating or retrofitting transportation facilitiesâ many of which are designed to have long service livesârequires that transportation planners and engineers consider how climate changes will affect the performance of these facilities 50 or more years into the future. Opportunities for adaptation are limited once a facility has been renovated unless engineers build in the potential to make subsequent changes. Addressing climate change will also require reevaluation, develop- ment, and regular updating of design standards that guide infrastructure design. Environmental factors are integral to the design of transportation infrastructure. Conditions such as temperature, freezeâthaw cycles, and duration and intensity of precipitation determine subsurface and founda- tion designs, the choice of materials, and drainage capacity. Engineers, however, have given little thought to whether current design standards are adequate to accommodate climate change. For example, will drainage capacity be adequate for expected increases in intense precipitation events? Many infrastructure components are currently designed for the 100-year storm, but projections indicate that todayâs 100-year precipita- tion event is likely to occur every 50 or perhaps even every 20 years by the end of this century. What new materials and operating practices might be needed when very hot temperatures and heat waves become more fre- quent? Are infrastructure components sufficiently strong to withstand the forces of larger and more frequent storm surges and more powerful wave action, the effects of which were vividly demonstrated when Hurricane Katrina simply lifted bridge decks off their supporting structures? Developing standards is a time-consuming consensus process that typically involves professional organizations in an extensive research and testing program. Changes in design practices tend to be incremental, and building to higher standards to strengthen transportation infrastructure so it can accommodate the adverse impacts of climate change must be weighed against the costs involved.
202 Potential Impacts of Climate Change on U.S. Transportation Recommendation 9: USDOT should take a leadership role, along with those professional organizations in the forefront of civil engineering practice across all modes, to initiate immediately a federally funded, multiagency research pro- gram for ongoing reevaluation of existing and development of new design standards as progress is made in understand- ing future climate conditions and the options available for addressing them. A research plan and cost proposal should be developed for submission to Congress for authorization and funding of this program. Developing standards to address climate change in a timely manner requires leadership by the scientific community and professional associ- ations and, given the scope of the potential impacts, a broadly based, federally sponsored research program. The initial focus of such a program should be on essential links in transportation networks, particularly those vulnerable to climate changes in coastal areas or in low-lying areas in riverside locations. A good model is the congressionally mandated National Earthquake Hazard Reduction Program, begun in 1977, which established a research effort and a coordination mechanism to reduce the risks to life and property from earthquakes through the development of standards that afford different levels of protection for different levels of risk. If a similar program is to be launched to address climate change in a timely manner, it should be initiated soon. Recommendation 10: In the short term, state and federally funded transportation infrastructure rehabilitation projects in highly vulnerable locations should be rebuilt to higher standards, and greater attention should be paid to the provi- sion of redundant power and communications systems to ensure rapid restoration of transportation services in the event of failure. Following Hurricane Katrina, for example, the Federal Highway Administration recognized that current design standards for coastal high- way bridgesâwhich were based on a riverine environment and a 50-year stormâwere inadequate. The agency approved and shared in the cost of rebuilding bridges damaged in the hurricane to a higher design standard, and it recommended the development of bridge design standards more
Summing Up 203 appropriate for a coastal environment, which take into account the com- bined effects of storm surge and wave action and assume a more severe storm event (e.g., a 100-year or even a 500-year storm). AASHTO is lead- ing the effort to develop a new consensus standard. Hurricane Katrina also showed the importance of power and communications systems to the restoration of transportation services (e.g., operation of traffic lights, rail signal systems, pumping stations, air traffic control facilities, and night- time running lights). Finding: Federal agencies have not focused generally on adapta- tion in addressing climate change. The development of appropriate design standards to accommodate cli- mate change is only one of several possible adaptation strategies that may require federal leadership, research, and funding. Recommendation 11: USDOT should take the lead in devel- oping an interagency working group focused on adaptation. This initiative would not necessarily require new funding beyond that recommended above. Better collaboration among federal agencies could help focus attention on adaptation issues and shape existing research programs. Transportation Planning and Land Use Controls Finding: Transportation planners are not currently required to consider climate change impacts and their effects on infrastruc- ture investments, particularly in vulnerable locations. One of the most effective strategies for reducing the risks of climate change is to avoid placing people and infrastructure in vulnerable loca- tions. Transportation planners currently consider expected land use patterns when forecasting future travel demand and infrastructure needs. However, they rarely question whether such development is desirable, much less what effects climate change might have on the provision and development of infrastructure in vulnerable locations. In part, this situa- tion stems from governance arrangements. States, regional authorities, and the private sector are responsible for large-scale transportation
204 Potential Impacts of Climate Change on U.S. Transportation investment decisions, but local governments and a few states control land use decisions through comprehensive plans, zoning ordinances, permit- ting, and building codes. In some locations, transportation and land use planning are becoming more integrated as a result of smart growth poli- cies, which recognize the impact of transportation investments on regional development and economic growth and vice versa; however, such integra- tion is uncommon. Recommendation 12: Federal planning regulations should require that climate change be included as a factor in the development of public-sector, long-range transportation plans; eliminate any perception that such plans should be limited to 20 to 30 years; and require collaboration in plan development with agencies responsible for land use, envi- ronmental protection, and natural resource management to foster more integrated transportationâland use decision making. Current surface transportation legislation encourages such collaboration. During reauthorization, requiring transportation planners to both consider climate change and collaborate with land use planners in the preparation of public-sector, long-range plans could go a long way toward making these issues more visible. Some metropolitan planning organizations are already using scenario-based approaches to illustrate the trade-offs among social, economic, and environmental goals and understand the impacts of differ- ent long-range investment plans. Scenario planning could be adapted to take potential climate changes into account, and the results could provide the basis for discussion with local governments and developers responsible for land use decisions, particularly in vulnerable areas. Finding: Locally controlled land use planning, which is typical throughout the country, has too limited a perspective to account for the broadly shared risks of climate change. Any strategy that involves land use controls to address climate change would need to build consensus among key decision makers in transporta- tion and land use, probably at the regional levelâa challenging proposition. Federal and state incentives may be needed to encourage new organiza- tional arrangements, a topic discussed later in this chapter.
Summing Up 205 Insurance Finding: The National Flood Insurance Program and the flood insurance rate maps (FIRMs) that determine program eligibility do not take climate change into account. The federal government is the insurer of last resort for homeowners and businesses that cannot secure affordable private flood insurance in specially designated flood hazard areas. The National Flood Insurance Program, authorized by Congress in 1968 to mitigate increasing taxpayer-funded flood relief, is administered by the Federal Emergency Management Agency (FEMA). FEMA maps the nationâs floodplains, and eligible home- owners and businesses receive below-cost insurance. In return, the local community must adopt and enforce floodplain management measures, including building code ordinances for new construction and rebuilding after a disaster, to reduce flood damage. In practice, critics contend that the program has resulted in more development than would otherwise have occurred in these areas. Moreover, the accuracy of the FIRMs used to determine program eligibility is woefully inadequate, despite a map- ping modernization program. Flood hazard area boundaries are keyed to the 100-year storm, and base elevation data are inadequate. The maps are based on historical data and thus do not factor in such climate changes as sea level rise and storm surge. Recommendation 13: FEMA should reevaluate the risk reduc- tion effectiveness of the National Flood Insurance Program and the FIRMs, particularly in view of projected increases in intense precipitation and storms. At a minimum, updated flood zone maps that account for sea level rise (incorporating land subsidence) should be a priority in coastal areas. Climate change may trigger more intense storms, and sea level rise will extend the scope of flood damage in some special flood hazard areas. FEMA and congressional oversight committees should reevaluate the risk reduction effectiveness of the National Flood Insurance Program in light of these projected changes. The FIRMs should account for climate change and the likelihood that it will extend the boundaries of some special flood hazard areas, which are keyed to the 100-year storm. These changes are particularly important to transportation engineers because the FIRMs have
206 Potential Impacts of Climate Change on U.S. Transportation become a quasiâdesign standard, for example, for determining appropriate drainage capacity for transportation infrastructure in coastal areas. New Organizational Arrangements Finding: Current institutional arrangements for transportation planning and operations were not organized to address climate change and may not be adequate for the purpose. The impacts of climate change do not follow modal, corporate, or juris- dictional boundaries, yet decision making in the transportation sector is structured around these boundaries. Transportation planning is con- ducted primarily at the regional level, often through a bottom-up process that starts with local jurisdictions. Railroads, trucking, and waterborne commerce are largely private enterprises with varying levels of federal participation. Thus, existing institutional arrangements are not well suited to addressing climate change. Some models of cross-jurisdictional cooperation exist, such as regional authorities for specific facilities (e.g., the Alameda Corridor); regional and multistate emergency response agreements; and state-mandated regional authorities, such as those responsible for air quality improvement. One could imagine the emer- gence of similar arrangements to address, for example, the impact of sea level rise on coastal real estate and infrastructure in the tristate New York area or other coastal areas, or the effects of drought on shipping along inland waterways, or the impact of hurricanes in the Gulf Coast region. However, state or federal incentives may be required to ensure the development of such organizational arrangements at the regional or multistate level. Recommendation 14: Incentives incorporated in federal and state legislation should be considered as a means of address- ing and mitigating the impacts of climate change through regional and multistate efforts. For example, states could use updated FIRMs or their own state maps to identify geographic areas vulnerable to climate change and craft policies for restricting transportation investments and limiting insurance in these locations.
Summing Up 207 WHAT ACTIONS AND RESEARCH ARE NEEDED TO PREPARE FOR CLIMATE CHANGE? At the outset of this study, the committee was asked to provide recom- mendations on actions to be taken to prepare for climate change and on needed research. The committee interpreted this charge broadly, particu- larly as it applies to research. Many of its recommendations relate to the development and sharing of information, decision support tools, and new technologies and materials, as well as research more narrowly defined. The committee also attempted to identify who should implement each of its recommendations. Actions to prepare for climate change can be taken almost immediately. The committee recommends that transportation agencies and service providers inventory critical infrastructure in light of climate change pro- jections (Recommendation 1); incorporate climate change into their long-term capital improvement plans, facility designs, maintenance prac- tices, operations, and emergency response plans (Recommendation 2); incorporate more probabilistic investment analyses and design approaches and communicate the results of these analyses to policy makers in ways that highlight trade-offs and investment priorities (Recommendation 3); and build on the experience of locations where transportation is well integrated into emergency response and evacuation plans to prepare for projected weather and climate extremes (Recommendation 6). Other steps depend on federal and state action. Federal planning reg- ulations should require inclusion of climate change in the development of long-range plans and collaboration between transportation and land use agencies (Recommendation 12); state and federally funded trans- portation infrastructure rehabilitation projects in highly vulnerable locations should be rebuilt to higher standards until design standards can be assessed more broadly in light of climate change (Recommendation 10); FEMA should reevaluate the risk reduction effectiveness of the National Flood Insurance Program and update the FIRMs, both in light of climate change (Recommendation 13); and federal and state legisla- tion should incorporate incentives to encourage the development of regional and multistate efforts to address the impacts of climate change (Recommendation 14). Research needs, broadly defined, include establishing a process for better communication among transportation professionals, climate sci- entists, and other relevant scientific disciplines and a clearinghouse for
208 Potential Impacts of Climate Change on U.S. Transportation transportation-relevant information on climate change (Recommendation 4); developing climate data and decision support tools that incorporate the needs of transportation decision makers (Recommendation 5); developing and implementing monitoring technologies for major transportation facilities to provide advance warning of pending failures due to severe weather events and climate extremes (Recommendation 7); developing a mechanism for sharing best practices to address potential impacts of climate change (Recommendation 8); initiating a federally funded, multi- agency research program for reevaluation of existing and development of new design standards to address the impacts of climate change, including a research plan and cost proposal for immediate submission to Congress (Recommendation 9); and creating a federal-level interagency working group focused on adaptation (Recommendation 11). Most of these ini- tiatives would require federal action; others would require action by professional organizations and university researchers. In all cases, leader- ship and continuing commitment would be essential. REFERENCES Abbreviations IPCC Intergovernmental Panel on Climate Change NRC National Research Council IPCC. 2007. Summary for Policymakers. In Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor, and H. L. Miller, eds.), Cambridge University Press, Cambridge, United Kingdom, and New York. NRC. 2007. Evaluating Progress of the U.S. Climate Change Science Program: Methods and Preliminary Results. National Academies Press, Washington, D.C.