New Analysis Finds Rising Seas Threaten US Infrastructure Critical for Millions of People, Hundreds of Communities

WASHINGTON—Climate change is rapidly worsening tidal flooding and escalating risks to essential and valuable coastal infrastructure that millions of people depend on. According to a new analysis released today by the Union of Concerned Scientists (UCS) titled “Looming Deadlines for Coastal Resilience,” nearly 1,100 critical infrastructure assets along the U.S. coastline would flood 12 times per year on average, or the equivalent of once a month, by 2050, assuming a medium rate of sea level rise. That number could jump to more than 5,300 critical infrastructure assets at risk by 2100. With tidal flooding risks to expensive, long-lived infrastructure growing rapidly in the decades ahead, policymakers and decision makers from every sector of society must take urgent actions to prepare communities and sharply curtail the use of fossil fuels driving the climate crisis.

“Our society depends on infrastructure like subsidized housing, wastewater treatment facilities, power plants, and hospitals reliably providing services. If these facilities are flooded even just once, it can be incredibly disruptive or even paralyzing to daily life,” said Dr. Kristina Dahl, the lead report author and a principal climate scientist at UCS. “Communities don’t have long to prepare before their vital coastal assets are routinely under threat from climate change-caused flooding. Our analysis shows that by 2030, the amount of critical infrastructure at risk of repeat flooding along U.S. coastlines is expected to grow by 20% compared to 2020 conditions.”

“There’s a rapidly approaching deadline for many coastal communities that demands urgent attention,” said Erika Spanger, a report author and the director of strategic climate analytics at UCS. “Even if their homes stay dry, disruptive flooding of vital infrastructure could leave people essentially stranded within their communities or enduring intolerable and even unlivable conditions. It’s imperative that policymakers plan and invest in safeguards and solutions now to limit the worst outcomes to people’s health and safety.”

According to the report, by 2050 and assuming a medium sea level rise scenario:

• As many as 1,662 of today’s critical infrastructure assets would be at risk of being flooded, on average, twice annually. Of those assets, 1,094 would be at risk of flooding the equivalent of once each month and 934 the equivalent of once every other week.
• The critical infrastructure at risk of flooding, on average, monthly includes a total of 390 public housing buildings and affordable housing units, 260 industrial contamination sites, 198 public health and safety buildings, 122 power plants and electrical substations, 43 government facilities, and 38 educational institutions.
• The 703 coastal communities with at-risk critical infrastructure are currently home to nearly 2.9 million people.
• The number of critical infrastructure assets at risk of disruptive flooding is expected to nearly double compared to a 2020 baseline.

By 2100, assuming a medium sea level rise scenario (3.2 feet globally, on average, by century’s end):

• As many as 6,533 of today’s critical infrastructure assets would be at risk of being flooded, on average, twice annually. Of those assets, 5,337 would be at risk of flooding the equivalent of once each month and 4,797 the equivalent of once every other week.
• The critical infrastructure at risk of flooding, on average, monthly includes a total of 2,359 public housing buildings and affordable housing units, 920 industrial contamination sites, 836 public health and safety buildings, 518 power plants and electrical substations, 383 educational institutions, and 321 government facilities.
• The 1,758 coastal communities with at-risk critical infrastructure are currently home to nearly 7.4 million people.
• The number of critical infrastructure assets at risk of disruptive flooding is expected to increase more than sevenfold compared to a 2020 baseline.

The amount of sea level rise experienced along U.S. coastlines by century’s end is less certain, with the release of more heat-trapping emissions increasing the likelihood of greater sea level rise. If sea level rises by 6.5 feet globally, on average, even more critical infrastructure in the United States and its territories could be at risk. Under such conditions, as many as 13,620 assets would be at risk of flooding the equivalent of once a month.

Using a combination of data from National Oceanic and Atmospheric Administration (NOAA) tide gauges, U.S. government agencies, and three sea level rise scenarios developed by a U.S. Interagency Task Force—referred to as high, medium, and low in the report—UCS determined when critical infrastructure assets along the entire coastline of the contiguous United States, as well as Guam, Puerto Rico and the U.S. Virgin Islands, would be at risk of being routinely flooded by high tides at least two, 12 or 26 times per year, on average, in the coming decades. Critical infrastructure is defined in the analysis as assets and facilities that provide functions necessary to sustain daily life or that if flooded could impose societal hazards. The analysis includes results for 2020, 2030, 2050 and 2100 for six types of critical infrastructure: educational institutions, energy infrastructure, government facilities, industrial contamination sites, public health and safety buildings, and subsidized housing. It also utilizes the White House Council on Environmental Quality’s Climate and Economic Justice Screening Tool to ascertain if the infrastructure at risk of flooding is located in “disadvantaged” or “non-disadvantaged” communities, as defined by the tool. Factors that contribute to a community being considered disadvantaged include burdens they face related to health, housing, climate change and income. This analysis only considers present-day infrastructure and population data, which means the results may be conservative. More information about the methodology used in this report can be found here.

Due to a variety of factors—coastline length, sea level rise rate, land subsidence and zoning laws—some states have more critical infrastructure assets exposed to disruptive tidal flooding in the coming decades than others. The analysis finds that California, Florida, Louisiana, Maryland, Massachusetts, and New Jersey have the highest numbers of critical infrastructure assets that will need to be made more resilient or be relocated to safer ground. Meanwhile, because of longstanding racial and socioeconomic inequities, disadvantaged communities that already carry heavy burdens have, on average, more infrastructure at risk of flooding and fewer resources to address this challenge. According to the analysis, about one-third of coastal communities are currently designated as disadvantaged, but they are home to more than half of the critical infrastructure at risk through 2050. Disadvantaged communities with infrastructure at risk have higher percentages of Black, Hispanic or Latino, and Native American residents and more infrastructure at risk per capita than non-disadvantaged communities. Public and affordable housing represents the single most at-risk category of vital infrastructure.

“Our analysis finds that communities identified as disadvantaged have twice as much critical infrastructure at risk per capita through 2050 compared to communities that are not designated as disadvantaged. There also tends to be more than one type of essential infrastructure at risk in disadvantaged communities,” said Dr. Juan Declet-Barreto, a report author and senior social scientist for climate vulnerability at UCS, who is available for interviews in English or Spanish. “That could translate into parents being forced to drive their kids longer distances to new schools, flooding of polluted soil and land contaminating local water supplies, or a fundamental and overwhelming loss of a sense of community. Failing to prioritize resilience solutions in these communities risks reinforcing the harmful legacy of environmental racism and colonialism in places already grossly underserved and overlooked.”

The report offers a range of recommendations for policymakers and public and private decision makers to ensure communities are adequately prepared for the risks and challenges that lie ahead. The recommendations include using the best available science to inform near- and long-term risk planning and scaling up public and private funding—beyond allocations in existing policies such as the Infrastructure Investment and Jobs Act—to increase the climate resilience of coastal infrastructure. The report also encourages implementing policies to reduce historical inequities and prevent future harms, protecting subsidized housing when possible, opening just opportunities for people or communities that opt to relocate, and planning for a wide range of possibilities that could occur as sea level rise rapidly accelerates.

“In some cases, it may make sense to elevate or construct flood defenses around lifeline infrastructure,” said Shana Udvardy, a report author and senior climate resilience policy analyst at UCS. “Protective, science-informed flood standards and building codes, together with investments in natural climate solutions, are crucial for protecting essential infrastructure. These types of investments can save as much as thirty-one dollars for every one dollar spent. Ultimately, not all communities will be able to fully adapt their way out of the challenges posed by worsening sea level rise and they should receive support from policymakers in considering their options for managed retreat from the coastline.”

Even if all global heat-trapping emissions ceased today, much of the expected sea-level rise between now and midcentury is already locked in due to insufficient efforts to reduce emissions by policymakers to date, and the obstructive and damaging actions of fossil fuel companies. However, the amount of sea level rise that occurs between 2050 and 2100 depends on global heat-trapping gases released over the next several decades and Earth’s physical response—namely the extent of land-based ice loss and ocean warming—caused by those emissions.

“Our findings are a clarion call to policymakers, as well as decision makers from across every sector of society, to significantly ramp up transformative and equitably shared investments in climate resilience within this decisive decade and beyond,” said Dr. Rachel Cleetus, a report author and the policy director of the Climate and Energy Program at UCS. “The serious flooding threat to public and affordable housing deserves special attention. If not urgently addressed, it will compound the ongoing affordable housing crisis. We must focus on smart risk management and avoid business-as-usual choices that are needlessly exposing more infrastructure—and the communities they serve—to harmful and costly flooding. Sharply curtailing heat-trapping emissions, phasing out fossil fuels and ramping up clean energy solutions must also be cornerstones of actions to help protect coastal communities.”

To view the report PDF, click here.

Spreadsheets with UCS data on the infrastructure at risk in specific states and communities are available for the following timeframes: 2020, 2030, 2050 and 2100.

To use the interactive mapping tool, click here. The map allows you to learn more about the infrastructure at risk in specific communities or states. When you zoom in, the maps become more detailed.

For all other materials, including state press releases, report methodology, case studies, and Spanish-language materials, click here.