Adaptation Tool Kit: Sea-Level Rise and Coastal Land Use

Climate change is happening. Past greenhouse gas emissions have committed us to decades of rising temperatures and seas. Recent studies, factoring in ice-sheet melt, estimate that we may experience an average of up to 6 feet of sea-level rise across the globe over the next century. The potential physical and fiscal impacts of sea-level rise (SLR) are stark.

We are already seeing increasing erosion of our beaches and the inundation of low-lying wetlands. Physically, SLR will intensify impacts from storm surge, flooding, and erosion. Fiscally, governments will need to spend large amounts of money on emergency response and to rebuild flooded infrastructure. Valuable government tax base and significant private investment will literally fall into the sea. And, if governments fail to plan for these impacts, legal fallout is a certainty.

Governments have powerful reasons to begin planning and adapting now. Emergent ad-hoc responses to climate impacts will put people, property, and scarce financial resources at risk. However, governments need not invent entirely new methods to address these impacts. State and local governments have an assortment of tools that they have used to address other land-use problems (such as flooding and sprawl) that they could refashion and use to adapt. This Tool Kit describes 18 different land-use tools that can be used to preemptively respond to the threats posed by SLR (see Table 1 on the next page). This Tool Kit focuses on land-use tools that could be used to adapt to impacts to the built environment (public and private coastal development and infrastructure).

In order to devise a comprehensive strategy, governments will need to determine which tools to employ given their unique socio-economic and political contexts. To this end, we also provide policymakers with a framework for decision making. We analyze each tool by (1) the type of power exercised to implement it (planning, regulatory, spending, or tax and market-based tools); (2) the policy objective that it facilitates (protection, accommodation, planned retreat, or preservation); and (3) the type of existing or potential land uses that the tool can be used to adapt (critical infrastructure, existing development, developable lands, and undevelopable lands). Finally, we provide a top-level analysis of the trade-offs between tools—the economic, environmental, and social costs and benefits, and the legal and administrative feasibility of implementing each tool. 



Statement of the Problem: Climate Change Impacts

Climate change is happening. Regardless of today’s mitigation efforts, past emissions levels have committed us to decades of rising seas. Recent estimates project that global sea levels may rise an average of approximately six feet over the next century. These estimates are based on new studies factoring in ice sheet melt dynamics that were not considered by previous studies generated by the Intergovernmental Panel on Climate Change (IPCC). These estimates also do not account for regional variability; impacts will be worse in certain parts of the United States because of land subsidence and other factors.

The potential physical and fiscal impacts of sea level rise (SLR) are stark. Physically, SLR will inundate large areas of the coast and exacerbate flooding and erosion. Climate change is also anticipated to increase the intensity of large storm events (such as hurricanes and nor’easters), which will drive storm surge further inland. Rising seas will inundate and drown existing wetlands and erode coastal beaches and barrier islands. Species that live in these vulnerable habitats will be threatened.1 

Fiscally, governments may be forced to spend large amounts of money on emergency response, insurance payouts, and rebuilding flooded infrastructure. Economic activities may be disrupted. Valuable government tax base and significant private investment may literally fall into the sea.

For example, the Virginia Middle Peninsula Planning District Commission completed an analysis of the economic impacts that one foot of SLR will cause to its constituent counties. In one small town, New Point Comfort, it estimated that one foot of SLR will destroy 72 homes and their septic systems and a quarter mile of road, causing $17.8 million in damage. Across all six counties within the District, it estimated between $212 million and $249 million of damage. If these costs are extrapolated across all 29 coastal counties, Virginia is facing roughly $5 billion in damage from one foot of SLR (a rate below the lowest scenario of SLR for the state).2 

What is less clear is how people will respond to these threats. Historically, landowners facing flood risks have built protective structures, to the detriment of natural resources. In Florida, after being battered by Dennis, a category 3 hurricane, landowners demanded the right to protect themselves from the sea. Feeling the pressure, local governments permitted temporary protective measures, which resulted in the construction of 15-foot steel sea walls along 26 miles of the Florida coast.

Landowners became embroiled in lawsuits against local, state, and federal officials. State officials were forced to intervene because sea walls have the effect of compounding flood risk; they erode beaches and drown the wetlands that serve as natural buffers. The U.S. Fish and Wildlife Service also intervened because the sea walls were preventing endangered sea turtles from reaching their nesting beaches.

As shown in Florida, reactive, ad hoc responses to impacts can provoke lawsuits between landowners seeking to protect their private property and public entities seeking to preserve natural resources. Landowners whose land values are diminished challenge new land-use regulations by arguing that government has “taken” their property without just compensation (so called “takings challenges”).14 Litigation can also be provoked between landowners, as one owner’s protective structure exacerbates flooding and erosion to adjacent properties and causes damage. To avoid these potential conflicts, it is imperative that governments begin planning and adapting now.

How Governments Can Respond to Impacts

The recent hurricanes in the Gulf Coast demonstrated the dangers of an unplanned response to natural hazards. SLR will increase the vulnerability of coastal communities to hazards such as flooding and hurricanes. This could pose serious economic, social, and environmental consequences. How society responds to SLR may exacerbate these consequences if we fail to implement measures to adapt to the inevitable physical changes that we are beginning to see along our coasts. In order to make a plan to adapt, policymakers will need to choose from a wide variety of potential responses—each with its own costs and benefits.

Government responses can be categorized in two ways: (1) reactive or proactive responses and (2) structural or non-structural responses. Communities that respond proactively have more flexibility. First, reactive responses are actions that a government takes after impacts have already occurred. Reactive response can include rebuilding restrictions, requirements that rebuilt structures be retrofit to be more resilient to impacts, and buyouts of lands with damaged structures.

Reactive responses also frequently utilize structural solutions. Traditionally, property owners have managed flood and erosion with engineered structures like the sea walls (“armoring”) built in Florida. However, decisionmakers are increasingly recognizing the limitations and impacts of armored solutions. Armoring is costly to build and maintain and can increase flooding and erosion of neighboring properties. Armoring can increase risks from catastrophic failure because it facilitates development in vulnerable areas (as demonstrated by the failure of levees in New Orleans during Katrina). Armoring also has damaging environmental impacts to beaches and wetlands. 

Alternatively, a proactive response involves advance planning and implementation of measures that are designed to preemptively mitigate the negative consequences from natural hazards and human responses to those hazards. By engaging in proactive planning, governments can facilitate the use of non-structural solutions to protect against risks. Non-structural solutions include using land-use measures to ensure that development is more resilient to flooding and erosion, and to reduce the cost and difficulty of a long-term retreat strategy.

Proactive non-structural solutions are often more cost effective over the long term and less environmentally damaging than reactive responses. Communities can use these tools to limit their exposure to hazards, save lives, limit public expenditures on armoring and emergency response, and protect valuable natural resources that provide natural flood protections and other environmental services. Although implementing proactive measures may cost more in the short term, over the long term, as impacts increase, proactive adaptation can yield significant
cost savings.

While beneficial, changing long-term land-use patterns requires significant advance planning. In order to effectively reduce risks, governments will need to determine their vulnerabilities, identify appropriate responses, and begin altering how they regulate development now. In the aftermath of a disaster, decision makers face significant political pushback against new regulations. This Tool Kit will help policymakers identify and weigh different solutions so that they can plan for and begin to adapt to SLR before impacts occur.

The Difficulty of Adaptation Planning

Recognizing the risks posed by climate change, many coastal state and local governments have begun or completed plans to adapt. However, these plans expose the numerous obstacles facing decision makers. Many plans propose broad adaptation policies, but lack specific guidance on how adaptation policies can be implemented on the ground. State and local governments are facing significant budget shortfalls and often cannot dedicate staff to address adaptation planning on top of their ordinary work load.

Adaptation planning is challenging for many reasons. Climate science is technical and complex; global climate models consider a multitude of variables to project future scenarios. The projected rate of SLR varies under each scenario; and the rate and degree of SLR will depend on the rate of future greenhouse gas emissions, the rate of increases in temperature, and ice sheet melt, among other things.

Additionally, some areas of the coast will be much more vulnerable to SLR impacts than others. Some areas of the coast are particularly low-lying or have highly erosive beaches. SLR will vary based upon local conditions—groundwater withdrawal, extraction of oil and gas, and other geologic factors are causing land to subside in certain regions. As a result, scientists are uncertain about the extent of SLR and the time period over which it will occur, especially at local and regional levels.

Although there are reams of reports written about the science of climate change, its impacts, and potential responses, little of this information is written or organized to help decision makers actually make decisions on the ground. Most reports are technical and focus on impacts from a global or national perspective. Few, however, help decision makers understand how their particular locality will be affected. Even fewer help them effectively identify and evaluate which policy options to adopt in their local context.

The Difficulty of Implementing Adaptive Measures

Decision makers face even more barriers when moving from the planning stages to actually beginning to implement adaptive actions. Politically, decisions affecting property rights are always controversial. Property owners facing increased flooding and loss of land expect to be able to protect their property and their investments. However, governments that fail to require adaptation will be requiring the community as a whole to pay for the costs of protecting some coastal properties. Taxpayer money will need to be used to provide emergency response to flooded communities and to rebuild flooded infrastructure.Private protective measures may destroy natural resources that provide important public benefits. Beaches and wetlands serve as natural flood buffers and habitats for endangered species. Wetlands also filter polluted runoff. The public uses beaches for recreation, and beaches generate significant tourist revenues. When implementing adaptation measures, governments will have to balance these public and private trade-offs.

Legally, governments face even more challenges. In order to implement a particular measure, governments face many legal questions:

  • Does the government have adequate legal authority to take action?
  • Is this action consistent with other state, and federal laws?
  • Are there federal, state or other entities with competing powers or overlapping jurisdiction over
    impacted resources?
  • Could implementation of a policy prompt litigation and could a community be liable for failing to act?
  • Is this action constitutional? Could this action be challenged as a regulatory taking under the Fifth Amendment?

These legal uncertainties are stymieing government action.

This Tool Kit seeks to help governments overcome these challenges by identifying existing land-use tools. Adapting to climate change will not require governments to reinvent how they regulate. State and local governments already use a multitude of tools to manage development in their communities. These tools have been used to effectively address other land-use problems, such as urban sprawl and flooding. Governments may be able to minimize the complexities of adapting by using existing powers in new ways.


Synopsis of SLR Adaptive Tools