Coastal Planning Failures: Rising Seas Can Worsen Inequities

August 10, 2016 | 9:53 am
Brenda Ekwurzel
Senior Climate Scientist, Director of Climate Science

The State of the Climate in 2015 assessment, just released by the American Meteorological Society, has confirmed that 2015 clocked in with the highest global sea level for Earth over the satellite record period.

Ignoring the accelerating pace of sea level rise has already created some coastal planning failures when waves overtop prior coastal protection measures. This situation too often leads to “emergency” decisions, which then set up the high risk for future planning failures.

First let’s explore what is at stake, how we got to this state of affairs, and some ideas for how to address coastal flooding risks exacerbated by climate change going forward.

Global Sea level through 1993-2015

Image source: NOAA, adapted from the 2015 assessment (Blunden, J. and D. S. Arndt, Eds., 2016: State of the Climate in 2015. Bull. Amer. Meteor. Soc., 97 (8), S1–S275).

Costly risks to coastal communities and taxpayers if we ignore climate change


This post is part of a series on Planning Failures: The Costly Risks of Ignoring Climate Change.

Recent studies from Antarctica suggest that even higher sea level rise by the end of this century seems more likely than before, if climate change continues unabated.

Based on a six-foot sea level rise by the end of the century, a new report estimated the risks to be over $882 billion  based on a survey of current home price estimates combined with data from NOAA. This estimate is based on the risks of ground floors being submerged, assuming no local defenses (i.e. adaptation measures) beyond current levels, and it excludes the value of commercial properties (see figure below).

Adding the value of commercial properties would greatly expand the potential cost risks. Add to this critical infrastructure at risk, such as the approach to the new Bay Bridge in California that would be inundated under 3 feet of sea level rise, and the costs would escalate substantially.

Potential underwater home value with 6 feet of sea level rise in the U.S.

More than $882 billion is potentially at risk of homes being underwater by 2100 if sea levels rise by 6 feet in the US and no further adaptation measures are taken. Costs do not include future appreciation in home value. Graphic created by B. Ekwurzel based on data from Zillow

Most coastal communities prefer to stay in place; US coastal county populations are growing denser, far outstripping non-coastal counties.Many of these communities have cherished resources listed in the National Register of Historic Places after passage of the National Historic Preservation Act (50th Anniversary in 2016). Not just historic buildings or artifacts, but cultural heritage is increasingly at risk. Iñupiaq residents of North Slope Borough, Alaska are resorting to solar-powered ice cellars to preserve traditional food traditions and stave off food insecurity.

Other communities with high risks to cultural heritage, health, and livelihoods and little options left for in-place adaptation, in Alaska, Louisiana, and Florida, are considering relocation. The lack of adequate governance or funding is compounding the problems posed by climate change.

Unintentional consequences of historic and current efforts to help protect coastal communities

Recognizing the immense importance of coastal communities and that haphazard shore protection measures plagued the US, Congress passed the Rivers and Harbors Act (PL 71-520) in 1930. This Act gave authority to the U.S. Army Corps of Engineers to work with local governments to study shore protection measures, but not implement such measures.

After hurricanes in the early 1960s, PL87-874 changed the federal cost share from 33% to 100% for shore protection studies. Lessons were learned about hardened structures such as vertical seawalls that reflect back the wave energy that also took away the original sandy beach.

U.S. harbor dredging volume fiscal year 2000

Harbor dredging provides materials that can be used in beach nourishment. Graphic: Morang and Chesnutt 2004, US Army Corps of Engineers.

The trend in enhancing resilience moved away from hardened structures and toward coastal protection measures that mimic natural shorelines such as beach nourishment. The US Army Corps of Engineers’ mission to protect navigation in harbors provides a ready supply of material for beach nourishment. For example, the harbor dredging projects in fiscal year 2000 removed 218 million cubic meters of material from federally constructed and maintained channels. This would fill 87,200 Olympic size swimming pools.

One major challenge is the vast amount of shoreline to protect. Between the local, state, and federal statutes, which projects go forward and when? Timing could become critical. During storm warnings some communities have pointed to insufficient shore protection, often due to delays in construction.

An assessment of storm damage after tropical cyclone Sandy demonstrates the costs of insufficient protection measures, including flood zone regions not adequately taking into account science-based sea level rise and insufficient building construction.

An assessment of the California coastal protection measures declared that public and private sector decisions have historically favored “protection of the built environ­ment over preservation of at-risk public trust resources such as beaches, public access and recreation, wetlands, and intertidal habitats.”

Local initiatives have aimed at offsetting this trend such as in Gulfport, Mississippi. Residents in the Turkey Creek community have worked for equitable access to resilience funding to preserve wetlands, cultural heritage, and rebuild livelihoods. A core principle of a planning failure is unequal distribution of risk across a system. “If the distribution of impacts on economic and social well-being is significantly uneven, this strategy should be considered” a planning failure [sic].

Better options going forward

Communities on the front lines, government planners, and nonprofit organizations are discussing improved policy options going forward, such as targeted funding and prioritizing building resilience for communities most at risk. Many have recognized the need for greater support for better integration of community planning under local and state statutes with hazard prevention/ mitigation planning primarily under the federal Stafford Act.

The idea for “adaptive governance” has been offered as a critical process for climate-induced community adaptations, especially for relocation. These authors, Bronen and Chapin, recommend a multi-pronged approach to address communities choosing along a continuum of responses from post-disaster recovery, protection in place, hazard mitigation, and relocation:

  • Amend the federal Stafford Act to include climate-induced processes and release federal funds for pre-disaster hazard mitigation and planning.
  • Change state and federal statutes to permit federal agencies to assist with building new infrastructure.
  • Create a new institutional framework to provide technical assistance and remove statutory barriers that impede the choice of relocation.

What are your experiences with coastal planning failures and what are your ideas for policies that work toward climate resilience that incorporates science-based adaptation?