Officials in Charleston, S.C., are clear that climate change poses an existential threat. They are working on plans to build a $1.1 billion sea wall that would protect historic homes from the increasingly powerful hurricanes that have repeatedly threatened the booming city. And in his state of the city address this year, Mayor John Tecklenburg said Charleston must “rezone every inch of our city” to put an end to development in flood-prone areas.

The dilemma faced in Charleston, whose population grew 25 percent from 2010 to 2020, can be found throughout the Southeast. Many cities and counties in the region are confronting the reality that rapid development has made them more vulnerable to hurricanes, storms and tidal flooding caused by sea level rise. The region has grown quickly, though unevenly, over the past decade and is expected to add millions more people in the decades ahead. As wetlands and forests have given way to homes and hotels, there is a lot more property — and millions more people — directly in harm’s way.

Ian came ashore in Florida as one of the strongest storms ever to strike the state, causing a storm surge of over 12 feet in Fort Myers, and knocking out power to more than 2 million people. The southwest suffered widespread destruction, with houses washed off their foundations, bridges destroyed and massive flooding.

From 2010 to 2020, census records show, the top two fastest-growing metro areas in the United States were The Villages, a retirement community in Florida, and Myrtle Beach, S.C. Over that same period, the rate of population growth in Florida, Georgia, South Carolina, North Carolina and Tennessee exceeded the national average while other states like West Virginia and Mississippi saw declines. Florida’s population grew at an astonishing pace over that decade, adding more than 2.7 million people.

“Severe weather events are certainly one cost people are considering, but based on the data, these benefits, at least for many, seem to clearly outweigh the costs,” Von Nessen said. Census projections suggest the Southeast will see the largest population gains over the next two decades, through 2040.

Realtors aren’t required to disclose the flood history of the properties they sell and finding that information can be difficult. In addition, many of the Federal Emergency Management Agency’s flood maps are decades out of date and don’t account for sea level rise or flooding from sudden rain storms. Earlier this year, the agency announced it was considering reforms to these policies, as well as its flood insurance program, but it has yet to release a proposal.

“If every Realtor was required to tell people, ‘You should know over the period of your mortgage your home will flood at least once, maybe twice,’ I think people would go, ‘Whoa, what?” said Rob Moore, a senior policy analyst at the Natural Resources Defense Council, an environmental advocacy group. “But due to policy failures in state capitals and in Washington we have made it extremely difficult for people to not only find that information but to even tell people about it.”

In South Florida, cities have adopted stronger building codes that require the use of building materials that can withstand high winds. Officials in Miami are focused on elevating roads and homes to protect them from sea level rise and encouraging inland development, away from low-lying areas.

In Norfolk, where tidal flooding regularly makes roads impassible, the effects of climate change along the more-than 200-mile shoreline can’t be ignored. Officials overhauled the zoning regulations in 2018 to direct development to higher ground in the city. They adopted a scoring system that evaluates proposed projects based on their ability to withstand flooding and other hazards. The city is also planning to protect its downtown by building a system of storm surge barriers, levees, and pump stations.

Gavin Smith, an expert in disaster resilience at North Carolina State University, said poorer cities, especially those whose tax base has already been eroded by cascading disasters, have struggled to put together applications for federal grants to strengthen fragile infrastructure. Residents interested in federal buyouts sometimes have to wait years for FEMA approval. And many communities are reluctant to take action at all.

With Democrats’ Inflation Reduction Act, which President Biden signed into law last month, expected to send billions of dollars to coastal states for climate projects, “there is possibility,” Smith said. “Time will tell if it’s unrealized potential or if there’s going to be a more wholesale shift.”

Chris DeScherer, a lawyer at the center’s Charleston office, said that the sharp contrast between city officials’ public acknowledgment of flood risk and their willingness to approve development in a vulnerable location demonstrates one of the city’s central challenges: how to adapt to climate change while welcoming an influx of new residents.