Rising Seas May Force U.S. Climate Refugees to the Same 5 Cities

But even if people escape sea-level rise, they’ll have other climate-related dangers to deal with

Credit: Google Earth

The year after Hurricane Katrina hit New Orleans in 2005, over 60,000 families were forced to relocate to other parts of the country. Nearly 10,000 of them ended up in Houston. Since then, thousands more around the U.S. have had to retreat inland because of extreme storms, flooding and sea-level rise linked to climate change. As sea levels rise up to eight feet by the end of the century, climate refugees will increasingly seek shelter away from the coasts.

By 2100, as many as 13 million people in the United States could be forced to move inland, according to a study published in PLOS One in January. And certain cities, the authors of the study argue, must brace themselves to receive the majority of these climate refugees.

Atlanta, Houston, Dallas, Denver, and Las Vegas will be among the most popular relocation destinations, say the researchers, whose machine learning model predicts an influx of hundreds of thousands of climate refugees from America’s Atlantic, Pacific, and Gulf Coasts by 2100. These cities, all of which besides Houston are landlocked, are already common destinations for people to migrate to for non-climate-related reasons, which the researchers from the University of Southern California (USC) call “business-as-usual” migration.

They will likely see even more people moving inland because, with the exception of Houston, of their distance from the coasts, as well as their ability to offer housing, jobs and infrastructure, all of which the study took into account when factoring in forced migration patterns. Now, officials in these cities must brace for increased demands on water, transportation, energy infrastructure, and housing markets.

Areas even further inland, however, must also be ready for a shift in population, says study co-author Bistra Dilkina, a computer scientist at USC. Though the main cities will see a larger total increase than rural communities, the percentage increase in population will likely be greater in small settlements, particularly in the Great Plains and Appalachia, that may be even less equipped to handle the influx.

“If you think about a city that has the infrastructure and the services and everything planned for the scale that the city currently is, and then it gets a 10% increase in population, that’s a bigger kind of socioeconomic shock than getting 3%, even if that 3% in a big city is a bigger absolute number,” she says.

The most recent study to project climate migration in the U.S. was published in Nature in 2017 by Mathew E. Hauer, who at the time was a demographer with the University of Georgia. Hauer’s work also projected millions of Americans migrating inland from the coast to inland cities including Austin, Orlando, Atlanta, and Houston. But what makes the new USC model different is that it accounts for both forced migration specifically due to climate change as well as historic trends in migratory patterns around the country. The 2017 study only involved the latter.

Fortunately, all of the cities singled out by the climate model have already begun preparing, says Dilkina. People who have been involved with planning in Atlanta, Las Vegas, and Denver spoke to OneZero about their preparations.

Atlanta’s first Climate Action Plan, developed in 2015, informs how the city will prepare for 2040, the year the city’s population is expected to have tripled in size, in part due to climate migration — from 400,000 to 1.2 million.

“It’s sad that people have to leave their homes where they’ve lived their entire lives and that they have to mobilize because of climate change,” said Jairo Garcia, who helped develop the plan as Atlanta’s former director of climate policy and renewables. “But without the right planning, it’s going to put a lot of pressure on cities like Atlanta.”

“Just escaping sea level rise in the coastal region and moving a little bit further inland, that’s not going to do you a whole lot of good.”

The city’s 2040 Development Plan, folding in recommendations from the Climate Action Plan, outlines a strategy to extend its resources for an expanded population. One section of the document calls for “significantly more and improved public space to support the life of our growing city.” Most climate migrants, it predicts, will not have their own outdoor space. Plans to develop housing focus on densely populated communities, like apartments and condominiums, rather than single-family homes. The city is also preparing to become more public transit-oriented, with four bus rapid transit lines criss-crossing Atlanta’s metropolitan area and “off-street superhighways for bicycles” that follow old railroads in the area.

Like Atlanta, Las Vegas’ increased housing stock “can’t be all single-family residential development,” says Marco Velotta of Vegas’ Planning Department, who’s working on the city’s 2050 Master Plan. Part of their strategy will be to focus on infill — developing vacant or underused land — and redevelopment of existing land use, as well as transit-oriented development. Doing so will keep the cost of extending infrastructure and the demand on resources much lower than they would be if they built more single-family homes in the suburbs of Vegas.

Officials from Denver are also planning for an increase in the city’s population and the potential impacts of climate change. David Gaspers, Denver’s principal city planner and project manager of Blueprint Denver, the city’s development plan, says the strategy is to direct development toward “high-growth” areas of the city, which have more transit options and are more walkable. The city is also studying how to incentivize affordable housing development in these areas so “people don’t have to be vehicle-dependent,” says Laura Swartz, spokesperson for the city’s Planning and Development department.

The other two cities mentioned by Dilkina’s team, Houston and Dallas, also have climate action plans, though neither directly addresses population growth.

Moving inland, however, won’t address all the hazards that climate change may bring. In fact, it’s possible that climate migrants may simply be trading one climate-influenced danger for another. Both Garcia and Velotta pointed out that the cities, especially Las Vegas, are at an increased risk of drought in the coming decades due to climate change.

Neither of their cities is located close to a large body of water, at least relative to other major metropolitan areas. Atlanta is reliant on the Chattahoochee River, which also supplies the rest of Georgia, Alabama, and Florida, while Las Vegas depends on Lake Mead and a small portion of the Colorado River, making both cities susceptible to dry spells. As recently as 2007, parts of the Southeast including Atlanta experienced one of the worst droughts in at least 100 years.

Velotta says that a source from the Southern Nevada Water Authority sent him the USC study to “highlight it” for the work his team is doing to prepare for an increase in Vegas’ population.

“Just escaping sea level rise in the coastal region and moving a little bit further inland,” he says. “That’s not going to do you a whole lot of good.” But he says that the city could withstand a population increase in most of the drought scenarios the region’s water authority has projected.

Dilkina says that she hopes her team’s predictions will prepare other cities to welcome migrants from the coasts. However, no matter how many of the larger cities in the landlocked U.S. are preparing for climate migrants, it remains difficult to predict all the ways in which different parts of the country will be affected by climate change — which highlights an important truth: Most people in the world, let alone the U.S., will not be able to fully escape its effects.