finding 8.3 : key-message-8-3

As the pace and extent of coastal flooding and erosion accelerate, climate change impacts along our coasts are exacerbating preexisting social inequities, as communities face difficult questions about determining who will pay for current impacts and future adaptation and mitigation strategies and if, how, or when to relocate. In response to actual or projected climate change losses and damages, coastal communities will be among the first in the Nation to test existing climate-relevant legal frameworks and policies against these impacts and, thus, will establish precedents that will affect both coastal and non-coastal regions. (Likely, Very High Confidence)

This finding is from chapter 8 of Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II.

Process for developing key messages:

The selection of the author team for the Coastal Effects chapter took into consideration the wide scope and relative sufficiency of the Third National Climate Assessment (NCA3) Coastal chapter. With input and guidance from the NCA4 Federal Steering Committee, the coordinating lead authors made the decision to convene an all-federal employee team with representation from key federal agencies with science, management, and policy expertise in climate-related coastal effects, and to focus the content of the chapter on Key Messages and themes that would both update the work conducted under NCA3 and introduce new themes. For additional information on the author team process and structure, refer to Appendix 1: Process.

A central component of the assessment process was a chapter lead authors’ meeting held in Washington, DC, in May 2017. 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 a review of the existing literature and by ongoing interactions of the author team with coastal managers, planners, and stakeholders. In addition, the author team conducted a thorough review of the technical inputs and associated literature. Chapter development was supported by numerous chapter author technical discussions via teleconference from April to September 2017.

Description of evidence base:

Reports and peer-reviewed articles are clear that socioeconomic challenges are being both driven and intensified by climate change.5d78768d-4392-494e-90c1-466cd61644c7 Particularly on the coasts, where there are multiple risks to contend with, including hurricanes, SLR, shoreline erosion, and flooding, the high cost of adaptation is proving to be beyond the means of some communities and groups.17dfdc09-42c6-48e9-8756-88f04887a960,00d193af-455c-4c08-9a6f-a3ada2072ece,dc1d0674-3b6f-428d-8849-8bda585e7b3f In areas where relocation is more feasible than in-place adaptation, coastal tribes of Indigenous people are at risk of losing their homes, cultures, and ways of life as they seek higher ground (Ch. 15: Tribes, KM 3).15012d21-a3e9-41fe-93b6-65e2fba81f10,4db14d8e-7eb2-4c27-8d52-daf0ee96f014 New tools are being developed to quantify risks and vulnerabilities along the coast. For example, tools such as the Coastal Community Social Vulnerability Index30b236e8-d525-40dc-a4f6-a7b5e6e56401 and the Coastal Economic Vulnerability Indexd4e56643-d8b8-4955-98b7-e593b3a664f8 measure the social vulnerability of hurricane- or flood-prone areas to better quantify and predict how climate-driven changes are likely to impact marginalized groups. The Coastal Flood Exposure Mapper toolf7c40fbd-81b6-43dd-a483-9cbd73025d18 supports communities that are assessing their coastal hazard risks and vulnerabilities with user-defined maps that show the people, places, and natural resources exposed to coastal flooding. The U.S. Environmental Protection Agency’s Environmental Justice Screening and Mapping Tool provides consistent national data that allows the agency to protect the public health and environments of all populations, with a focus on traditionally underserved communities.2b6d802a-c666-4acd-be5a-93d2343eddff Moreover, involving diverse representation in the adaptation process through community-driven resilience planningec4d3830-c3b9-491b-9bc0-facccd717e00 is likely to be a part of developing adaptation strategies that are fair and just.87cfc4e1-f44b-4fb0-ae65-cbeec57ebfac,a56b0da0-aa66-4e7b-b46f-c18455a4b459

New information and remaining uncertainties:

The main uncertainty for this Key Message is predicated on how different types of coastal effects (chronic flooding versus storms) will impact areas and communities along the coast. The degree of variation between communities means that it will be challenging to predict exactly which communities will be affected and to what extent, but the evidence thus far is clear: when it comes to climate-driven challenges and adaptation strategies, areas that have traditionally been underrepresented will continue to suffer more than wealthier or more prominent areas. Large-scale infrastructure investments are made in some areas and not others, and some local governments will not be able to afford what they need to do.

The variability in state laws and the pace at which those laws are evolving (such as shoreline management plans and setback policies for structures in the coastal zone) create major uncertainty.

Assessment of confidence based on evidence:

There is very high confidence that structural inequalities in coastal communities will be exacerbated by climate change and its attendant effects (for example, storms, erosion). In the absence of clear policies and legal precedent, questions about land ownership and home ownership will persist.

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