Aerial view of Trustom Pond National Wildlife Refuge

A Natural Experiment Hints at an ‘Elegant Approach’ to Climate Adaptation

By Jon Gorey, January 25, 2023


As climate change creates ever more harm and havoc, one way governments are trying to keep people and property out of peril’s path is to steer new development away from the riskiest places. It’s a just goal whose execution is exceedingly complicated: Telling people where they can and can’t live or what they can do with their land is almost always a fraught endeavor. 

“How do you go about doing that very hard thing,” asks Margaret Walls, senior fellow at the nonprofit Resources for the Future, “when you have private property rights and so forth?” 

It turns out, a 41-year-old federal law may hold some answers to that question.  

In 1982, Congress did something that, by today’s standards, at least, seems almost unthinkable: It passed sweeping environmental legislation with overwhelming bipartisan support. The Coastal Barrier Resources Act (CBRA) had 58 cosponsors in the Senate, and sailed through the House in a 399–4 vote.  

The law initially placed some 450,000 acres of sensitive coastal areas and wildlife habitat along the Atlantic and Gulf of Mexico shorelines into the Coastal Barrier Resources System (CBRS). Congress has periodically approved the addition of more land over the years, and today the system, managed by the U.S. Fish and Wildlife Service, includes about 3.5 million acres, spanning from the Great Lakes to Puerto Rico. 

The CBRA’s purpose was twofold: to preserve some of our most delicate and dynamic coastal ecosystems, but also to discourage development—and to limit federal spending on things like flood insurance and disaster relief—in risky, storm-prone areas.  

It used a fairly simple policy mechanism to achieve those goals. The law didn’t actually prohibit development inside CBRS units, it simply withdrew some of the underlying federal supports that encourage growth, like infrastructure funding and access to federal flood insurance.  

“One thing that people talk about a lot is that we might be implicitly subsidizing people to live in [risky] places,” Walls says. For example, until recently, the National Flood Insurance Program had long offered coverage at rates that didn’t necessarily reflect the true cost of flood risk, making it less financially ruinous to roll the dice and build in a floodplain.  

It’s hard to isolate and quantify the effects of such subtle subsidies, Walls says. But by carving out designated areas “where you cannot get federal flood insurance, the federal government will not pay for infrastructure, like roads and so forth, and you will not get disaster aid if you’re hit by a disaster,” she says, “the Coastal Barrier Resources Act provides this natural experiment.” 

Four decades into that experiment, research is showing just how effective the CBRA has been at keeping homes out of harm’s way. Simply shifting the cost and risk of coastal development onto private property owners or local governments seems to have been a particularly powerful nudge—enough to prevent untold families from living in disaster areas waiting to happen, and to preserve hundreds of miles of fragile coastal ecosystems.  

In a study commissioned by the Lincoln Institute of Land Policy, researchers at Resources for the Future are using historical maps and geospatial machine learning to compare hundreds of CBRS units along the Atlantic and Gulf coasts with a matching set of “control units”—that is, areas that weren’t placed in the CBRS, but which easily could have been, because they shared similar geomorphic features and development density in the early 1980s. Among other criteria, “We looked at roads, we looked at elevation, and we looked at land cover in the ‘80s,” says environmental economist Yanjun ‘Penny’ Liao, a fellow at Resources for the Future.  

What the team has found so far, as described in the working paper, is that a CBRS designation reduced development by an astonishing 85 percent, as compared to within a control unit. That effect was consistent even in CBRS units facing high development pressure from nearby metro areas, Liao says.   

Amy Cotter, director of climate strategies at the Lincoln Institute, is hopeful this research can complement the organization’s work with the Climigration Network, to help communities that are wrestling with “incredibly difficult decision making” around rebuilding or relocating in the face of repeated flood disasters.  

“We see the way in which sea level rise and other chronic effects of climate change show no sign of abating and, in fact, show every sign of being faster and more severe than anticipated,” Cotter says. “How do we take what we know about market responses to government policies and incentives, and help develop programs that still allow people to practice self-determination and make choices, but with market signals that are actually more accurate and reflect the risk of creating a home in a particular place?”  

The Spillover Effect

Interestingly, the CBRA hasn’t just protected coastal lands, or the homes and lives of the people who might have otherwise built on them. The researchers are also studying spillover effects in communities within a two-kilometer radius of either a CBRS unit or a control unit.  

While development just about stopped inside CBRS boundaries after 1982, immediately adjacent areas saw a 20 to 30 percent boost in development density compared to communities near control units. CBRS-adjacent neighborhoods also had higher average property values.  

The RFF researchers believe they’re the first to document these spillover effects, which could offer important lessons for policymakers. For one thing, the study shows that the conservation of buildable land doesn’t have to erode a city’s property tax revenues. Liao says the increased rate and value of the development within two kilometers of CBRS units more than offset the property tax revenue the smaller, preserved areas could have generated had they been built up.  

And while there could be many reasons for the higher property values found in CBRS-adjacent areas, such as the prized proximity to a pristine piece of nature, Liao wonders if one of them could be the flood protection offered by undeveloped land. The researchers found that the intensity of flood damage, as measured by claims per $1,000 of coverage, was 25 percent lower in areas just outside a CBRS unit, as compared to communities next to control areas. 

“By conserving natural land inside the units, they can serve as a kind of buffer when there’s a storm,” Liao says, “so it can protect the land that’s right behind them.”   

Protected marsh in Quincy, Massachusetts
Houses perch at the edge of a marsh in Quincy, Massachusetts, that is part of the Coastal Barrier Resources System. Credit: Jon Gorey.

Cotter says the research offers a glimpse at a more sensible approach to policy in flood-prone areas. “What alternatives could we explore that would diminish not only the expense, but the real loss and trauma associated with the kind of damage that the flood insurance program intends to fix?” she asks. “What would it look like to designate more of these areas?” 

In fact, the U.S. Fish and Wildlife Service in April sent to Congress a set of revised maps that would add about 277,000 acres to the Coastal Barrier Resources System in nine states most impacted by 2012’s Hurricane Sandy. (One of the proposed sites, it turns out, is an area RFF researchers chose as a control unit, lending extra credibility to their mapping process.)  

The revised maps will only take effect once passed by Congress, but a Senate bill introduced in December would adopt the revisions, and already has bipartisan support. 

Walls would like to investigate that same question—and whether a similar program could work in inland areas facing riverine flood risk—with additional research. “Should we be thinking about more additions to the system? There’s still a fair amount of undeveloped land in risky coastal areas,” she says. “I don’t think we feel like we could completely weigh in on that yet . . . but I think it’s an interesting next question to look at.”  

Adapting the program for use in already developed flood-prone areas would be challenging; when the sites were chosen in 1982, CBRA units were virtually empty, with no more than one structure per five acres. But since the CBRA doesn’t actually ban development outright, a CBRS designation would leave any existing property owners in control of what is typically an agonizing decision. If coupled with pro-growth policies in better-protected places nearby, Cotter wonders if the combination could encourage and support people grappling with climate migration—nudging them toward a safer alternative that’s still within proximity of their jobs, childcare, and familial support networks. 

“If you can be surgical about your identification of those CBRS units, so that they not only prevent development in an at-risk area, but they preserve important buffers to an adjacent area, that sounds like a win-win,” Cotter says. “It suggests quite an elegant approach to preserving what you need in order to reduce the risk” in nearby neighborhoods.    



Jon Gorey is a staff writer for the Lincoln Institute of Land Policy.

Image: A stretch of coast in South Kingstown, Rhode Island, that contains land protected by the Coastal Barrier Resources Act. Credit: U.S. Fish and Wildlife Service.