Sea level rise, coupled with storm surge, will continue to increase the risk of major coastal impacts on transportation infrastructure, including both temporary and permanent flooding of airports, ports and harbors, roads, rail lines, tunnels, and bridges.

This finding is from chapter 5 of Climate Change Impacts in the United States: The Third National Climate Assessment.

Process for developing key messages: In developing key messages, the chapter author team engaged, via teleconference, in multiple technical discussions from January through May 2012 as they reviewed numerous peer reviewed publications. Technical input reports (21) on a wide range of topics were also received and reviewed as part of the Federal Register Notice solicitation for public input. The author team’s review included a foundational Technical Input Report for the National Climate Assessment, “Climate Impacts and U.S. Transportation.”6b4d3283-49dc-4b8d-830b-aa554e37279f Other published literature and professional judgment were also considered as the chapter key messages were developed. The chapter author team met in St. Louis, MO, in April 2012 for expert deliberation and finalization of key messages.

Description of evidence base: Estimates of global sea level rise are documented in Ch. 2: Our Changing Climate, Key Message 10 of this report. The prospective impact of sea level rise and storm surge on transportation systems is illustrated by the impact of recent hurricanes on U.S. coastlines. In addition, research on impacts of sea level rise and storm surge on transportation assets in particular regions of the United States demonstrate the potential for major coastal impacts (for example, CCSP 2008, Rosenzweig et al. 2011, and Suarez et al. 20058dbd70c4-cd8c-4dce-b27c-bfb412901e58 0127c256-83e6-4e22-9715-bfc0fbbfb8d9 78fbf40c-2639-480a-8410-5be748750f2b). Note that most existing literature on storm surge and sea level rise impacts on transportation systems is based on a global sea level rise of less than one meter (about 3 feet). The most recent projections include a potentially greater rise in global sea level (Ch. 2: Our Changing Climate, Key Message 10). In addition, the key message and supporting text summarize extensive evidence documented in “Climate Impacts and U.S. Transportation.”6b4d3283-49dc-4b8d-830b-aa554e37279f

New information and remaining uncertainties: As noted above, new estimates of global sea level rise have overtaken most of the existing literature on transportation and sea level rise in the United States. In addition, it is not clear that the existing transportation literature reflects recent USGS work on interactions between sea level rise, wave action, and local geology.5ddaab38-f315-487d-8b7a-bb322bb9b60c New global sea level rise estimates will enable the development of new regional estimates, as well as revision of regional coastal erosion and flood modeling. Such smaller scale estimates are important because transportation and other infrastructure impacts must necessarily be studied in a local context. Generally speaking, modeling of sea level rise impacts using existing USGS National Elevation Dataset (NED) data has well-understood limitations. Since NED data is freely and easily available, it is often used for preliminary modeling. More accurate and more recent elevation data may be captured via LIDAR campaigns, and this data collection effort will be necessary for accurate understanding of regional and local sea level rise and storm surge impacts.1bc74f07-688c-482c-a923-483f5d3de8b5 Accurate understanding of transportation impacts is specific to particular infrastructure elements, so detailed inventories of local and regional infrastructure must be combined with detailed and accurate elevation data and the best available predictions of local sea level rise and storm surge. Therefore, national assessments of sea level rise must be built on detailed local and regional assessments. Improved modeling is needed on the interactions among sea level rise, storm surge, tidal movement, and wave action to get a better understanding of the dynamics of the phenomena.

Assessment of confidence based on evidence: The authors have high confidence sea levels are rising and storm surge on top of these higher sea levels pose risks to coastal transportation infrastructure.

References :

• SAP 4.7. Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study (8dbd70c4)
• Developing coastal adaptation to climate change in the New York City infrastructure-shed: process, approach, tools, and strategies (78fbf40c)
• Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region. A report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research (1bc74f07)
• A Bayesian network to predict coastal vulnerability to sea level rise (5ddaab38)
• Climate Impacts and U.S. Transportation: Technical Input Report for the National Climate Assessment. DOT OST/P-33 (6b4d3283)
• Impacts of flooding and climate change on urban transportation: A systemwide performance assessment of the Boston Metro Area (0127c256)