Cities in coastal environments around the world, among the most vulnerable to sea-level rise from a changing climate, have experienced unprecedented growth since 1950. Several are thoughtfully considering how to adapt to a wet future. In Boston, we are looking at elevating roads, seawalls, or entire buildings; constructing new locks and flood gates; or building new ecological barriers, such as tidal marshes, to absorb higher water levels and storm surges.

Still, we must ask, “Is it enough?” Some geophysicists, evaluating ice melt of glaciers, suggest we may be looking at 10 feet of sea-level rise by the end of the century. At that rate, we’re no longer tinkering with road elevations: We need to be asking whether some coastal environments are suitable for habitation.

Several regions are now starting to consider “managed retreat” from the coast. One of the most highly publicized initiatives is in Isle de Jean Charles in Louisiana, 80 miles southwest of New Orleans. This vulnerable community of about 100 residents sits outside the federally approved align-ment for risk reduction along coastal Louisiana. Moreover, the area has seen nearly 98 percent of the marshes and wetlands around the peninsula wash away in recent decades, leaving a single road providing the only access.

In 2016, Isle de Jean Charles was awarded $48 million from the US Department of Housing and Urban Development to create a model for voluntary relocation of the entire community. The federal award has a special poignancy because much of the community represent multiple tribal nations that were pushed to this land during earlier westward expansion of the United States. Although still in the planning stages, the goal is to relocate the entire town approximately 40 miles north, creating a new, mixed-use community that will generate revenue and jobs to become self-sustaining.

Mathew Sanders, the project manager for the Louisiana Office of Community Development, describes the residents as “climate pioneers” and the effort as a test to “preserve a community’s cultural identity while creating an economic model that can become a transferable model to other communities for coastal retreat.” But the effort has required a significant investment in relationship building with the community following the distrust built up over centuries.

A second example is on Long Island in New York. Still rebuilding from Superstorm Sandy, the state of New York has initiated a study to explore a transfer of development rights program for Long Island. This would allow communities along the coast designated as “Extreme Risk Zones” to sell development rights into a “development rights bank,” which could then be resold to developments in higher, drier locations in the center of Long Island, ideally around historic downtowns and rail stations.

The program is still evaluating potential impacts and hurdles. One is legality: Currently, development rights can’t be transferred across municipalities. Other considerations include lost property tax revenue and the effect of those reductions on roads, utilities, schools, and emergency response and fire districts. Residents have mixed emotions about the proposal, but with more than 50,000 properties on Long Island in the Extreme Risk Zone, the program offers a marketdriven strategy to help strengthen communities while limiting exposure to future sea-level rise and storms.

Isle de Jean Charles and Long Island present a vision for the future that coastal communities are going to need to address. Both programs offer a contrast to more traditional property acquisitions, individual buyouts, or buyback schemes initiated by federal agencies following disasters in recent decades. Both present an opportunity for growing communities and supporting economic development. They offer an alternative for communities that may not have the density, population, or property values to justify a major investment in infrastructure to protect the community. They represent a tool we’ll need to sharpen as we face the reality that some areas are no longer suitable for habitation.