Study: Wealthy Americans flee floods and hurricanes, driving income migration

When climate disasters strike, survivors sometimes have to make difficult decisions about whether to rebuild or move to higher ground. But who is stuck in place, and who can afford to move to safety? And what do they bring with them when they go?

Two UVM researchers wanted to explore these questions. Building on their previous study examining American migration patterns from 2010 through 2020, Mahalia Clark and Gillian Galford expanded the scope of the research by digging into how different types of extreme weather, including floods, hurricanes, wildfires, tornadoes, and other storms, affected where Americans—and their household incomes—are moving.

“There hasn't been a ton of research that looks at how multiple different climate hazards affect human migration in the US,” says Clark, who is the study’s lead author, “and there’s even less on that migration’s economic impacts." Clark recently completed her PhD as a Gund Fellow at UVM.

The data showed that, in the aftermath of floods and hurricanes, higher-income households left affected communities at higher rates than other residents, taking their resources with them. If this trend continues, it could leave at-risk communities with smaller tax bases to recover and prepare for future flooding.

Clark and coauthor and Gund Fellow Gillian Galford used anonymous IRS data to examine human migration and household income from 2011-2021. They then overlaid county-level data on weather-related property damage from the publicly available SHELDUS database housed at Arizona State University to examine relationships with severe weather from 1995-2021.

The national study, published this summer in the journal Population and Environment, is a novel look at the relationships among human migration, income migration, and extreme weather events.

The data showed how people and household income flowed in and out of counties. For example, they found even when a county’s total population didn’t change much, wealthy households and less-wealthy households tended to cluster, contributing to more concentrated higher-income communities and lower-income communities.

The researchers modeled these migrations of people, and their income, in comparison to property damage from severe weather events.

“Hurricanes had an impact on both net migration of people and net migration of income,” Clark says. Fewer people (and less income) moved into hurricane-hit counties, with population and income shifts rising and falling together.

The Northeast, however, saw a slightly different response. Here, hurricanes had an outsized effect on income migration. The effect of hurricanes on income lost through migration was more than twice as strong as the effect on loss of actual people, suggesting that—relative to the average person—higher-income households were disproportionately likely to leave impacted counties.

“In the Northeast, we might be seeing those higher-income households being more responsive to this emerging threat,” Clark says.

In other words, people with money were more likely to move away from hurricane zones in the Northeast relative to lower-income residents, and while new households replaced some of those who moved, the new residents were likely to have less means.

Compared to hurricanes, flood damage had little impact on migration rates of people: the net numbers of households in flood-affected communities remained largely unaffected throughout the study period, and those who left were replaced by similar numbers of new arrivals. Again, income was a different story; following a year when destructive flooding occurred, income migration dropped in affected communities, though the effect was less pronounced than with hurricanes.

“This suggests that you have either more higher-income households leaving, or fewer higher-income households arriving in those places,” Clark says. “On average, the household income of the people leaving is higher than the average household income of people coming in.”

Clark says it appears that households that had the means to make an intentional choice were more likely to leave after a destructive flood or hurricane—and if higher-income households  continue to depart, taking their economic resources with them, the negative impacts in the communities left behind could be significant, from loss of a tax base to fund basic services, to reduced ability to recover following a climate catastrophe, or prepare for the next disaster.

“One thing that I took away as a researcher is that it's really important to study these different types of natural climate hazards individually and compare and contrast their effects,” she says.

Previous studies had tended to lump various types of severe weather together as a single variable, but by teasing apart the differences here, Clark and Galford noticed that wildfires, tornadoes and other types of storms did not have the same impacts that hurricanes and floods  had on human migration.

Now, Clark is considering next steps, especially as climate change brings more extreme weather to new regions.

“I think there's a lot of places where it's worth looking at this on the local level… and thinking about who can afford to move out of the most exposed neighborhoods,” Clark says.

She says understanding the income-based divergence in migration choices following extreme weather events will also help state and local planning officials get “resources to where they're needed to support the families that need help to get out of harm's way.”

The needed research is on the horizon at UVM through the recently launched Climate Measurements Center of Excellence. Housed at the Gund Institute, and directed by Galford, who is a professor in the Rubenstein School of Environment and Natural Resources, the center is creating standardized tools for state, local, and regional climate assessments so they can be more easily used.  

“We’re learning where these severe climate events are happening, and the human dynamics within these events,” Galford says. “This knowledge is especially needed when the net number of people in and out of a community does not tell the whole story of who's being affected by climate disasters, or who is actually able to move.”

Story URL: Wealthy Americans Flee Foods and Hurricanes, Driving Income Migration

Study: Exodus of the affluent? Examining climate hazards, migration, and household income in the U.S.