As many as 13.1 million US residents could be displaced this century by rising sea levels

A new study published recently in Nature Climate Change takes population growth into account when trying to understand the impact of climate change, and the results are startling.

As many as 13.1 million US residents could be displaced by rising sea levels by 2100.

“Living in a place like Florida … over the past, you know, 20 to 30 years, I've watched people move in to these areas along the coastlines — rapid growth,” says Jason Evans, an assistant professor of environmental science at Stetson University. “And what we realized is that this growth is ongoing. … If you factor in this growth, it’s basically on a collision course.”

Evans says this will cause a big economic impact. 

“$300 million is right now being spent in Miami Beach on things like pumps and elevating roads,” Evans says. “With each community that's along the coast and as we're making decisions about growth, what we really want to study … [is] how much is it going to cost? How much risk is there to people to live in these very vulnerable areas? And then for infrastructure that we build, how much is it going to cost to maintain it?”

Many coastal areas in the United States are already beginning to see the impact of rising sea levels, according to Evans. And as sea levels rise more, it will become increasingly difficult to maintain infrastructure. 

“We talk about king tides a lot," Evans says. "These are the annual high tides that we see each year and these are very natural occurrences. But as we see with sea level rise now, the king tide that 30 years ago would have just been a minor problem, now you have water going into the streets. In some areas we actually see things like storm sewers, they'll run the wrong way. And so once you start seeing this, that's when you really get the attention of local governments and then we're starting to do studies to say OK, how much is it going to cost to adapt?”

Evans says there are some built-in natural features that may help absorb the impact of rising sea levels — ecosystems like coastal marshes and dune fields. But he says it’s important to learn more about maintaining and working with these systems. He also says it’s important to continue convincing politicians of the importance of recognizing and dealing with climate change. 

“We know southeast Florida is the area in terms of just the sheer amount of people,” Evans says. “This is a very consistent result. It’s just the most vulnerable within the entire United States. … This is a problem that we really need to deal with.”

This article is based on an interview that aired on PRI's Science Friday.