The impact of rising sea levels could trigger a mass migration that would force millions of coastal Americans inland, according to a new study by USC researchers.

The study, published in the scientific journal PLOS ONE last week, found that more than 13 million people could be displaced by 2100. As a result, cities throughout the country will be forced to reckon with significant population growth that could impact everything from infrastructure to housing prices to competition for jobs.

“Sea level rise will affect every county in the US, including inland areas,” said Bistra Dilkina, associate director of USC’s Center for AI for Society, one of the study’s authors.

Sea-level rise related to global warming is primarily caused by two factors: melting glaciers and ice sheets and the expansion of sea water as it warms. By the end of the century, six feet of ocean-level rise would redraw the coasts of southern Florida, parts of North Carolina and Virginia and most of Boston and New Orleans, according to the study. In Los Angeles, six feet of sea level rise will flood portions of Long Beach.

The southeast portion of the United States will experience the greatest impact of rising sea levels. (PLOS ONE)
The southeast portion of the United States will experience the greatest impact of rising sea levels. (PLOS ONE)

The study is the first to use machine learning—a subset of artificial intelligence—to project migration patterns resulting from sea level rise. The results identified the landlocked cities of Atlanta, Houston, Dallas, Denver and Las Vegas as the most popular relocation choices. Suburban and rural areas in the Midwest are also predicted to receive disproportionately large levels of population growth.

“Our findings indicate that everybody should care about sea-level rise, whether they live on the coast or not,” Dilkina said in a statement to the press. “This is a global impact issue.”

Although the study focuses on future patterns, its predictions have already begun to materialize in coastal regions around the world. In 2017, Hurricane Harvey battered the Texas coast and displaced thousands of residents to areas further inland. The government of Indonesia recently announced plans to relocate its “sinking” capital of Jakarta to the forested area of Borneo, and an entire village in Newtok, Alaska, is moving nine miles inland to escape from rising tides. At the end of 2019, viral images of flooding in Venice, Italy, made headlines across the globe.

Flooding in Venice, Italy, in December 2019. (Luigi Costantini/AP)
Flooding in Venice, Italy, in December 2019. (Luigi Costantini/AP)

Dilkina said she and the other researchers hope their findings will compel urban planners and local decision-makers to prepare for climate migrants. Jonathan Eyre, an assistant research professor at the USC Price School of Public Policy, has studied the impact of climate catastrophes on urban environments, and said housing should be the first priority for recipient cities.

“The fundamental crunch here is going to be how well people can integrate into new cities,” he said. “A big part of that is going to be needing a new place to live.”

Still, it’s not as simple as picking up and moving. Eyre said climate migrants could wind up in cities and towns dealing with their own set of environmental challenges.

“People in the middle of the country may not be concerned about sea level rise, but there are other aspects of climate change—like temperature and precipitation variants—that can do things like decrease crop yields,” Eyre said. “Climate change is going to rock those economies pretty hard.”

The researchers used five different models to examine potential outcomes of rising sea levels in the US. (PLOS ONE)
The researchers used five different models to examine potential outcomes of rising sea levels in the US. (PLOS ONE)

Although the USC study calls the impact of sea-level rise “potentially catastrophic,” those who have spent significant time researching the subject still maintain a sense of sense of optimism.

“I’m actually pretty happy living in LA,” Dilkina said. “I am hoping that climate adaptation strategies can possibly minimize some of the projected impacts.”

Eyre echoed these sentiments.

“It’s important to remember that there are opportunities for adaptation. People can rebuild in ways that are more resilient. People do adapt.”