Leaders and residents of coastal regions are increasingly aware of the high vulnerability of coasts to climate change and are developing plans to prepare for potential impacts on citizens, businesses, and environmental assets. Significant institutional, political, social, and economic obstacles to implementing adaptation actions remain.

This finding is from chapter 25 of Climate Change Impacts in the United States: The Third National Climate Assessment.

Process for developing key messages: A central component of the assessment process was a Chapter Lead Authors meeting held in St. Louis, Missouri in April 2012. The key messages were initially developed at this meeting. Key vulnerabilities were operationally defined as those challenges that can fundamentally undermine the functioning of human and natural coastal systems. They arise when these systems are highly exposed and sensitive to climate change and (given present or potential future adaptive capacities) insufficiently prepared or able to respond. The vulnerabilities that the team decided to focus on were informed by ongoing interactions of the author team with coastal managers, planners, and stakeholders, as well as a review of the existing literature. In addition, the author team conducted a thorough review of the technical input reports (TIR) and associated literature, including the coastal zone foundational TIR prepared for the National Climate Assessment (NCA).c9647af9-db7f-4f6a-89bd-2f2293ad26e5 Chapter development was supported by numerous chapter author technical discussions via teleconference from April to June 2012.

Description of evidence base: The key message and supporting text summarize extensive evidence documented in the coastal zone technical input report.c9647af9-db7f-4f6a-89bd-2f2293ad26e5 Technical input reports (68) on a wide range of topics were also received and reviewed as part of the Federal Register Notice solicitation for public input, along with the extant literature. Evidence base is moderate to strong: the results on which this key message relies are based on case studies, direct observation and “lessons learned” assessments from a wide range of efforts, surveys, and interview studies in ongoing adaptation efforts around the country.73adf935-9e46-4ded-a0ec-4ffaab4972ba There has been some planning for remediating climate change impacts, including recent publicationsb05e9b8a-0d38-4352-b4f4-4267f8b1b4f8 21f975c5-1795-430a-a6e9-3d76ceb9ef62 70a33826-8d8c-448f-ad8f-350406274a61 089d8050-f4c8-4d07-bc35-25bf61691be3 and there are publications on the lower social acceptance of certain adaptation option (for example, Finzi Hart et al. 2012; Peach 2012b05e9b8a-0d38-4352-b4f4-4267f8b1b4f8 54923781-b746-4f6e-8fac-5e1c3a141dd9) and on the many barriers that affect adaptation.e631bb4f-7e97-4596-9ad5-8b6cacf4f29b bf9d4e9c-9bd0-4c48-a20c-eeb95b45ac8c 40cd1072-ac17-4dfa-ba98-a554bf1a0458 c5f52295-5859-404e-80ac-9fd0b3adf0df 85e480dd-ebed-4066-80fe-e3695aec9939 8ed42f5c-d3f0-4e0e-a8c8-6028796f19f9 4ff13ad9-eb13-4783-8202-dd39827dca89 ce5b6f46-24fa-4fe8-adce-f58fcdefa798 In addition, there is confirming evidence of very similar findings from other locations outside the U.S. (some, from Canada, were also submitted as technical input reports to the NCA), such as the United Kingdom, continental Europe, Australia, and others.99633bb9-f4ee-4c50-8953-440bf35fb13c bf9d4e9c-9bd0-4c48-a20c-eeb95b45ac8c 40cd1072-ac17-4dfa-ba98-a554bf1a0458 85e480dd-ebed-4066-80fe-e3695aec9939

New information and remaining uncertainties: Adaptation is a rapidly spreading policy and planning focus across coastal America. This was not previously captured or assessed in the 2009 NCAe251f590-177e-4ba6-8ed1-6f68b5e54c8a and is thus a major advance in understanding, including what adaptation activities are underway, what impedes them, and how coastal stakeholders view and respond to these emerging adaptation activities. Given the local nature of adaptation (even though it frequently involves actors from all levels of government), it is difficult to systematically track, catalog, or assess progress being made on adaptation in coastal America. The difficulty, if not impossibility, of comprehensively tracking such progress has been previously acknowledged.65ce3b87-d63b-4582-a9b5-f25510b64e97 This conclusion is reiterated in the Adaptation chapter (Ch. 28) of this report. While the findings and integrative key message stand on strong evidence, some uncertainties remain about U.S. coastal regions’ adaptive capacity, the level of adoption of hazard mitigation and other adaptation strategies, and the extent and importance of barriers to adaptation. Possibly the least well-understood aspect about coastal adaptation is how and when to undertake large-scale, transformational adaptation. Aside from the mentioned examples of relocation, no other examples exist at the present time, and further research is required to better understand how major institutional, structural, or social transformation might occur and what would be involved to realize such options.

Assessment of confidence based on evidence: We have very high confidence in this key message, as it is primarily based on studies using well-accepted social science research techniques (for example, surveys, interviews, and participant observation), replicated in several place-based case studies, and on a nationwide compilation of adaptation case studies. Consistency in insights and conclusions in these studies, and in others across regions, sectors, and nations, add to the confidence. As described above, a comprehensive catalogue of all adaptation efforts, and of related challenges and lessons learned, is difficult if not impossible to ever obtain. Nevertheless, the emerging insights and evidence from different regions of the country provide considerable confidence that the situation is reasonably well captured in the documents relied on here. The coastal stakeholders represented among the authors of the foundational technical input reportc9647af9-db7f-4f6a-89bd-2f2293ad26e5 confirmed the conclusions from their long-term experience in coastal management and direct involvement in adaptation efforts locally. Moreover, evidence from other regions outside the U.S. adds weight to the conclusions drawn here.

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