There is, and has always been, a bold American way to respond to major disasters: We don’t merely rebuild; we build bigger and stronger than before.

We do this regardless of what hits us. Chicago, incinerated by the great fire of 1871, quickly became the nation’s fastest-growing metropolis. San Francisco, which crumbled and burned in the 1906 earthquake, transformed into the cultural and financial hub of the West. New Orleans grew larger and more prosperous after the Mississippi River flood of 1927, and since September 11, 2001, real estate development in lower Manhattan has boomed.

Climate change forces us to abandon the rebuild-bigger strategy. The oceans are rising steadily, and storm surges are growing more powerful by the year. We can neither armor the entire coastline nor build walls to protect all our cities. The costs are too high and the consequences too severe for adjacent communities that would be affected by spillover.

As water traverses coastlines and riverfronts, the millions who have settled on the dry side will start asking whether they can stay there. In many cases—from small towns in Maine to significant portions of Miami, New York City and San Francisco—the answer will be no.

It’s time to start planning the unthinkable: a strategy for returning some of the most precious and valuable land we’ve developed back to our oceans and rivers. And in time, but sooner than you may think, we’ll need a program for resettling millions of people to higher ground. After Hurricane Katrina, several earth scientists and a few brave political officials argued that New Orleans should never have been built on such vulnerable land. They called for the government to shrink the city down to its safest areas, lest the next megastorm again batter those who have already been beaten. But the low-lying neighborhoods that suffered most from Katrina had heavy concentrations of African Americans and the poor, and these communities were woefully neglected during and after the storm. In the real politics of that disaster, refusing to help rebuild these communities was perceived as downright discriminatory. And though it hasn’t been easy, the most precarious New Orleans neighborhoods are returning.

The aftermath of Sandy is different. The 2012 hurricane killed 117 people, 72 of them in the U.S., damaged or destroyed some 650,000 homes, left more than 8 million households without power and generated more than $60 billion in damages. Sandy took aim at Staten Island, the largely white, middle-class and politically conservative borough that sits like a bull’s-eye at the center of the New York Bight. The storm delivered about 500 million tons of water to New York City at roughly 80 miles an hour, and Staten Island got the worst of it. More than 75,000 people along the eastern and southern shores were flooded out when storm surges up to 14 feet high deluged their homes. Twenty-three people died there; the small island accounted for more than half the state’s fatalities and nearly one third of the national toll.

The death and devastation on Staten Island may have been unsurprising, since the borough is a barrier island by nature and as such has absorbed the blows of many previous hurricanes. But residents’ response was startling. Rather than build back bigger, neighborhood associations demanded buyouts from the city and state. They loved their neighborhood, the local culture and the beach, but they’d grown weary of living in a floodplain and had lost the will to live with that risk. As Oakwood Beach resident Joe Monte told the press, “I’m done. I can’t handle it no more. Just get us out of there. I want to feel normal again.”

courtesy of getty images

Improbably, New York governor Andrew Cuomo agreed to bail out Monte and his neighbors—and at pre-storm market prices. Cuomo proposed buying out every homeowner in the three Staten Island neighborhoods that had mounted the most aggressive campaigns for Sandy relief: Oakwood Beach, Ocean Breeze and Graham Beach. The buyouts, part of a $400 million state pilot program, averaged $400,000, a price the governor deemed worth paying. “There are some places that mother nature owns,” Cuomo said. “I want to give this parcel [of land] back.”

Cuomo’s announcement delighted the successful petitioners, who called it “absolutely unbelievable” and declared themselves ecstatic. But residents in other vulnerable Staten Island neighborhoods left out of the pilot program have spent the past two years fighting, angrily and anxiously, for public support to move out of harm’s way.

For most of that time, their major opponent was former New York City mayor Michael Bloomberg, a skeptic of buyout programs for densely populated waterfront cities. “We cannot and will not abandon our waterfront,” Bloomberg stated. “It’s one of our greatest assets.” He pointed out that the latest FEMA maps place 400,000 New Yorkers and 70,000 buildings in areas at high risk of dangerous flooding. He didn’t believe public agencies could pay to relocate all of them to higher ground, and he didn’t think they should.

In Bloomberg’s view, sustainable urban planning requires denser development, even along the flood-prone coastline. Just as a century ago engineers began to design buildings that were more fireproof to reduce the risks of conflagration, today they’re designing stronger, more water-resistant structures and infrastructures to withstand coming storms. With these technologies, the Bloomberg approach to climate-change adaptation is the latest variation on the classic American recovery theme: Build bigger, build stronger, continue to grow.

Dense urban development is indeed important for reducing our carbon footprint and curbing climate change. It’s also politically convenient, because the growth machine—builders, real estate agents, developers and the like—supports it. But it doesn’t have to happen everywhere. It is folly to rebuild in places that may be submerged within half a century or in places that are under threat of dangerous flooding every day.

The pilot program to buy out homeowners on Staten Island is only beginning, and it’s too early to know what kind of model it will establish. But there are already a few clear lessons.

First, drawing boundaries that separate those who will receive public funds to relocate and those left to fend for themselves will be difficult and contentious. Second, not everyone who should move will want to, and it’s impossible to manage a retreat from dangerous land if residents won’t give it back.

Third, it’s going to be expensive. The government will never be able to buy out residents at full market value if the market doesn’t price in climate risks. About 124 million people, or 39 percent of the U.S. population, live in coastal counties. The $400 million New York program is a drop in the bucket compared with the price of relocating Miami or New Orleans. And when those cities go down, they won’t go alone.

Of course, there are other ways to adapt to climate change. An exciting design movement involves building water-resistant structures, such as homes with floodable first levels, and infrastructures, such as permeable street surfaces and resilient power grids. In 2012 policy makers in Congress began scaling back the federal flood-insurance subsidy program to remove dysfunctional incentives to develop new coastal property. And after Sandy, federal relief funds were restricted to projects rebuilding at least one foot above local flood guidelines. Not every coastal community needs to move, but even if only a small fraction does, the math becomes overwhelming, especially if we refuse to plan and invest in a climate-change strategy today.

Mother nature doesn’t care if we believe the science. She has already narrowed our options. We can either slowly give her coastal land back or wait for her to take it.