Americans Abandoning Neighborhoods Due to Rising Flood Risk, Study Finds

As flooding becomes more common due to the shifting and strengthening weather patterns and sea-level rise associated with climate change, so does climate migration.

New research by the First Street Foundation (FSF) has combined historic population change trends with flood risk data to reveal climate migration patterns happening in areas with high flood risk across the United States.

“Much of the world’s population is exposed to some kind of extreme weather event exacerbated by climate change. These events have been directly connected to impacts on human systems including economic, social, and political crises,” the authors of the study wrote. “Increasing flood exposure and losses are expected to drive population and demographic shifts in the U.S. Some projections estimate that globally, up to 216 million people may migrate due to climate change by 2050.”

The study emphasizes “Climate Abandonment Areas” — areas with population decreases between 2000 and 2020 that can be directly linked to flood risk related to climate change, a press release from FSF said.

The researchers put together population data from the 2020 U.S. Census with the Census Block — property specific data on flood risk from FSF. “Tipping points” were revealed where population change was directly impacted by high flood risk thresholds.

There are 113 million people who live in parts of the country where housing choices have already been affected by flood risk, the most extreme being Climate Abandonment Areas. These areas account for more than 818,000 Census Blocks and lost a total of 3.2 million-plus residents due to flooding from 2000 to 2020.

“There appears to be clear winners and losers in regard to the impact of flood risk on neighborhood level population change,” said Dr. Jeremy Porter, FSF’s head of climate implications research and a professor of sociology at the City University of New York, in the press release. “[T]he downstream implications of this are massive and impact property values, neighborhood composition, and commercial viability both positively and negatively.”

The study, “Integrating climate change induced flood risk into future population projections,” was published in the journal Nature Communications.

“This research is the first to find a systematic pattern in the historic population change data that shows climate migration is not something that will happen in the future, but it’s something that is already happening in the case of the most likely type of migration (local moves),” Porter told Axios.

In the next three decades, current Climate Abandonment Areas are predicted to lose 2.5 million more residents — an additional 16 percent — due to flood risk. Along with those declines, areas with high flood risk that are still seeing net population growth are projected to experience net population loss later on and become Climate Abandonment Areas.

“[T]he people that can afford to leave, leave, and people [who] can’t afford to leave end up staying in the community,” Porter said, as reported by The Hill. “You end up with a lot of vulnerable populations at risk.”

Emerging Climate Abandonment Areas are expected to reach the risk tipping point soon, eventually losing a total of five million residents — 24 percent of their population — by 2053.

“The population exposure over the next 30 years is a serious concern,” said Evelyn Shu, lead author of the paper and a FSF senior research analyst, in the press release. “For decades we’ve chosen to build and develop in areas that we believed did not have significant risk, but due to the impacts of climate change, those areas are very rapidly beginning to look like areas we’ve avoided in the past.”