Coastal Sensitivity to Sea Level Rise
Part III: Preparing for Sea Level Rise
U.S. Global Change Research Program
Other EPA-sponsored Climate Change Science Program Synthesis and Assessment Reports
- SAP 4.4: Preliminary Review of Adaptation Options for Climate-Sensitive Ecosystems and Resources
- SAP 4.6: Analyses of the Effects of Global Change on Human Health and Welfare and Human Systems
The U.S. Environmental Protection Agency (EPA), in collaboration with the U.S. Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA), has released a report that discusses the impacts of sea level rise on the physical characteristics of the coast, on coastal communities, and the habitats that depend on them. The report, Coastal Sensitivity to sea level Rise: A Focus on the Mid-Atlantic Region examines multiple opportunities for governments and coastal communities to plan for and adapt to rising sea levels.
Download specific chapters from Part III: Preparing for Sea Level Rise
- Chapter 10: Implications for Decisions (20 pp, 4.6MB)
- Chapter 11: Ongoing Adaptation (8 pp, 9.2MB)
- Chapter 12: Institutional Barriers (17 pp, 15.2MB)
Download specific text boxes from Part III:
For at least the last four centuries, people have been erecting permanent settlements in the coastal zone of the Mid-Atlantic without regard to the fact that the sea is rising. Because the sea has been rising slowly and only a small part of the coast was developed, the consequences have been relatively isolated and manageable. Part I of this report suggests, however, that a 2 millimeter per year acceleration of sea level rise could transform the character of the mid-Atlantic coast, with a large scale loss of tidal wetlands and possible disintegration of barrier islands. A 7 millimeter per year acceleration is likely to cause such a transformation, although shore protection may prevent some developed barrier islands from disintegrating and low-lying communities from being taken over by wetlands.
For the last quarter century, scientific assessments have concluded that regardless of possible policies to reduce emissions of greenhouse gases, people will have to adapt to a changing climate and rising sea level. Adaptation assessments differentiate “reactive adaptation” from “anticipatory adaptation”.
Part III focuses on what might be done to prepare for sea level rise. Chapter 10 (20 pp, 4.6MB) starts by asking whether preparing for sea level rise is even necessary. In many cases, reacting later is more justifiable than preparing now, both because the rate and timing of future sea level rise is uncertain and the additional cost of acting now can be high when the impacts are at least several decades in the future. Nevertheless, for several types of impacts, the cost of preparing now is very small compared to the cost of reacting later. Examples where preparing can be justified include:
- Coastal wetland protection. It may be possible to reserve undeveloped lands for wetland migration, but once developed, it is very difficult to make land available for wetland migration. Therefore, it is far more feasible to aid wetland migration by setting aside land before it is developed, than to require development to be removed as sea level rises.
- Some long-lived infrastructure. Whether it is beneficial to design coastal infrastructure to anticipate rising sea level depends on economic analysis of the incremental cost of designing for a higher sea level now, and the retrofit cost of modifying the structure at some point in the future. Most long-lived infrastructure in the threatened areas is sufficiently sensitive to rising sea level to warrant at least an assessment of the costs and benefits of preparing for rising sea level.
- Floodplain management. Rising sea level increases the potential disparity between rates and risk. Even without considering the possibility of accelerated sea level rise, the National Academy of Sciences and a Federal Emergency Management Agency (FEMA)-supported study by the Heinz Center recommended to Congress that insurance rates should reflect the changing risks resulting from coastal erosion.
Chapter 11 (8 pp, 9.2MB) discusses organizations that are preparing for a possible acceleration of sea level rise. Few organizations responsible for managing coastal resources vulnerable to sea level rise have modified their activities. Most of the best examples of preparing for the environmental impacts of sea level rise are in New England, where several states have enacted policies to enable wetlands to migrate inland as sea level rise. Ocean City, Maryland is an example of a town considering future sea level rise in its infrastructure planning. The chapter includes a text box on the historic response to sea level rise at the Jamestown colony.
Chapter 12 (17 pp, 15.2MB) examines the institutional barriers that make it difficult to take the potential impacts of future sea level rise into account for coastal planning. Although few studies have discussed the challenge of institutional barriers and biases in coastal decision making, their implications for sea level rise are relatively straightforward:
- Inertia and short-term thinking. Most institutions are slow to take on new challenges, especially those that require preparing for the future rather than fixing a current problem.
- The interdependence of decisions reinforces institutional inertia. In many cases, preparing for sea level rise requires a decision as to whether a given area will ultimately be given up to the sea, protected with structures and drainage systems, or elevated as the sea rises. Until communities decide which of those three pathways they will follow in a given area, it is difficult to determine which anticipatory or initial response measures should be taken.
- Policies favoring protection of what is currently there. In some cases, longstanding preferences for shore protection (as discussed in Chapter 6) discourage planning measures that foster retreat. Because retreat may require a greater lead time than shore protection, the presumption that an area will be protected may imply that planning in unnecessary. On the other hand, these preferences may help accelerate the response to sea level rise in areas where shore protection is needed.
- Policies Favoring Coastal Development. One possible response to sea level rise is to invest less in the lands likely to be threatened. However, longstanding policies that encourage coastal development can discourage such a response. On the other hand, increasingly dense coastal development improves the ability to raise funds required for shore protection. Therefore, policies that encourage coastal development may be part of an institutional bias favoring shore protection, but they are not necessarily a barrier to responding to sea level rise.
- For previous reports focused on the implications of rising sea level, go to Sea Level Rise Reports.