US Flood Risk to Spike by 2050 and Black Communities Are Disproportionately Threatened

The number of Americans exposed to flooding is expected to double in 30 years.

Hurricane Katrina Hits Gulf Coast
People come out of their homes to a flooded street after Hurricane Katrina hit the area with heavy wind and rain August 29, 2005 in New Orleans, Louisiana. . Mark Wilson / Getty Images

In 2005, the storm surge from Hurricane Katrina burst the levees in New Orleans, inundating low-income communities of color and leaving white neighborhoods relatively unscathed. Historical patterns of discrimination were compounded by a lackluster government response, leading to Kanye West’s famous accusation that “George Bush doesn’t care about Black people.” 

Now, a new study published in Nature Climate Change late last month suggests that, when it comes to the intersection of climate-fueled extreme weather and systemic racism, there may be more Katrinas in our nation’s future. The University-of-Bristol-led research team looked at exposure to flood risk in the U.S. today and by 2050 to find both were examples of environmental injustice in action. 

“The mapping clearly indicates Black communities will be disproportionately affected in a warming world, in addition to the poorer White communities which predominantly bear the historical risk,” lead author Dr. Oliver Wing, an Honorary Research Fellow at Bristol University’s Cabot Institute for the Environment, says in a press release. “Both of these findings are of significant concern.”

The Future of Flood Risk

The purpose of the study was to get a more accurate sense of how the climate crisis will contribute to flood risk in the U.S. over the next 30 years. 

“The present means by which flood risk is managed globally is predicated on the assumption that history is a good predictor of the future,” the study authors write. “Be it enforcing regulations within flood zones defined using historical water-level records, [modeling] the cost–benefit ratio of mitigatory actions on the basis of historical flood probabilities, or not considering future risk when permitting new development, ubiquitous flood risk management tools fail to recognize that the nature of floods is changing.”

The scientists sought to improve on current modeling by combining in-depth flood projections and property asset data to create a high-resolution estimate of U.S. flood risk. The study looked at risk through three main components, Wing explains to Treehugger in an email: risk, hazard, and vulnerability. 

“We use simulations of possible floods and their associated probabilities for the hazard component, exposure is represented by buildings and their contents, and vulnerability describes the damages that arise when buildings do get flooded,” he says.

The study concluded that flood risk in the U.S. would increase from $32.1 billion in 2020 to $40.6 billion three decades later, assuming a moderate greenhouse-gas emissions scenario.

“This is a 26.4% . . . increase across a typical 30-year mortgage term commencing today, a near-term impact that is essentially locked in climatically—that is, these projections hold even if dramatic decarbonization is undertaken immediately,” the study authors point out. 

They also showed that projected population change makes an important difference in assessing future risk, upping that risk by four times when compared to the impact of the climate crisis overall. 

However, the researchers weren’t only interested in how flood risk would impact the general U.S. population. They also wanted to “uncover the social justice implications of who bears present and future risk,” as the authors put it. 

Maps showing the distribution of U.S. flood risk (expressed as the annual average loss due to flooding) by county, and its projected change by 2050.


‘Social Justice Implications’

As it turns out, there are social justice implications to who bears or will bear the brunt of both current and future risk. The study is another example of how the climate crisis disproportionately impacts communities that are already vulnerable because of economic or racial injustice. 

“I like to [emphasize] that most of the climate change related flood risk is unaddressed historical risk; climate change just[] exacerbates it,” Wing tells Treehugger. 

The researchers used census-tract-level data from the 2019 American Community Survey (ACS) to determine which races and income groups were most at risk both now and currently. Today, impoverished white communities experience the greatest flood risk. However, over 30 years, the risk will shift from following economic to racial disparities. By 2050, census tracts that are more than 20% Black will see their risk increase at double the rate of communities that are less than 1% Black. This result was not dependent on income. 

Wing tells Treehugger that the study did not really delve into why this shift will occur, though part of it is geography. 

“Changing patterns of rainfall and sea level rise are particularly intense in the Deep South, where predominantly Black communities are generally concentrated,” he says. 

However, racist real-estate practices and extreme weather in the U.S. have combined to create unnatural disasters in the past, and the climate crisis is not making the situation any better. To return to Katrina, there was disproportionately less flood damage in white neighborhoods that had historically been the site of colonial plantations, as these homes had been built on higher ground, had better access to public transport and were protected from industrial activity, swamps, and developments like highways.  

 “Racial disparities in storm damage stem from centuries of white control over the characteristics of land occupied by African Americans—low elevations with high exposure to back-swamp flooding and poor access to transportation,”  Reilly Morse writes in the 2008 report Environmental Justice Through the Eye of Hurricane Katrina.

These historical inequalities contributed to the fact that people of color made up almost 80% of the population in flooded neighborhoods while 44% of those impacted when the levees broke were Black, according to the Center for Social Inclusion. 

Nor is Katrina an isolated incident. A 2021 paper looked at Hurricane Harvey, which flooded the Texas Gulf Coast in 2017, and found that minority and low-income groups had fewer resources to prepare for the storm, suffered disproportionate health impacts in the aftermath, and faced more hurdles in the recovery process. Beyond floods, a 2020 study found that the practice of red-lining–denying home loans or insurance to neighborhoods based on racial demographics–still impacts those neighborhoods’ exposure to heatwaves. Land surface temperatures in red-lined communities across the U.S. are approximately 4.7 degrees Fahrenheit (2.6 degrees Celsius) warmer than in non-redlined areas.

‘A Call to Action’

The fact that human policies can worsen the impacts of extreme weather events also means that we can take steps to lessen them. 

“The research is a call to action for adaptation and mitigation work to be stepped up to reduce the devastating financial impact flooding wreaks on people’s lives,” Wing says in the press release.

Because the paper deals with the next 30 years, the increased risk it finds can’t be combated by reducing greenhouse gas emissions (though this is still a good idea overall). Instead, it is important to make planning decisions that make communities flood-ready now.

“These kind of data can inform targeted mitigation measures – including relocation, retrofits, grey & green infrastructure, building codes, planning laws, flood insurance – to ensure what our models project transpires to be wrong,” Wing tells Treehugger. 

People living in at-risk areas can flood-proof their homes, buy insurance or move, but, especially for communities that face poverty or racial discrimination, there can be systemic reasons why they can’t take matters into their own hands. For example, 30% of households in New Orleans neighborhoods that flooded during Katrina did not have access to a car, as Morse points out, and yet they were living in communities that had been cut off by federal housing and transportation policies. 

“It is unfair to rely on individuals to solve national failures of investment and planning, however,” Wing says. “This has to be solved by governments at all levels.”

View Article Sources
  1. Wing, Oliver E. J., et al. "Inequitable Patterns of US Flood Risk In the Anthropocene." Nature Climate Change, vol. 12, no. 2, 2022, pp. 156-162., doi:10.1038/s41558-021-01265-6

  2. Allen, Troy D. “Katrina: Race, Class, and Poverty: Reflections and Analysis.” Journal of Black Studies, vol. 37, no. 4, 2007, pp. 466–68.

  3. Flores, Aaron B., et al. "Environmental Injustice in the Disaster Cycle: Hurricane Harvey and the Texas Gulf Coast." Environmental Justice, vol. 14, no. 2, 2021, pp. 146-158., doi:10.1089/env.2020.0039

  4. Hoffman, Jeremy S., et al. "The Effects of Historical Housing Policies on Resident Exposure to Intra-Urban Heat: A Study of 108 US Urban Areas." Climate, vol. 8, no. 1, 2020, p. 12., doi:10.3390/cli8010012.