Published in the journal Natural Hazards, the study examined Portland through a social, ecological and technological systems framework. Rather than treating each natural hazard as an isolated event, researchers analyzed how environmental threats interact with the built environment and with social conditions. The approach recognizes that a neighborhood’s risk is not determined only by whether it lies near a river or on a steep slope. Tree removal, drainage systems, housing patterns, transportation networks, historical zoning decisions and access to emergency services can all alter the consequences of a disaster. “We’re not just people experiencing natural hazards, but we’re in a system that interacts with the natural hazards,” said Justin Huber, a doctoral student in Portland State’s Earth, Environment & Society program and the study’s lead author.

The researchers created spatial assessments at two geographic scales: census block groups and census tracts. Block groups are relatively small statistical areas, generally containing several hundred to a few thousand residents, while census tracts cover larger populations and can reveal broader urban patterns. Using these scales allowed the team to examine both neighborhood-level inequality and citywide differences. Hazard layers for extreme heat, flooding, wildfire and landslides were combined with demographic and environmental data, including median income, educational attainment, racial composition, disability, tree cover, wetlands and the distance to hospitals. The result was a multi-hazard potential map designed to show where several forms of danger may overlap, rather than simply ranking neighborhoods according to one threat at a time.

The geography of individual hazards followed Portland’s distinctive terrain. Flooding and extreme heat were more common in the relatively flat areas of East Portland, where extensive paved surfaces can absorb and retain solar energy while low-lying land is more exposed to high water. Wildfire and landslide potential was concentrated in the hillier western parts of the city, where steep slopes and vegetated terrain create different environmental risks. When the four hazards were analyzed together, however, East Portland emerged as the city’s clearest multi-hazard hotspot. Neighborhoods near I-205 recorded some of the highest combined scores, demonstrating how a place that may not face the greatest risk from any single hazard can become highly vulnerable when threats are superimposed.

The social profile of these hotspots was striking. About 5 percent of Portland’s residents live in neighborhoods classified as facing the highest risk from three or more hazards. The 18 census block groups in this category had lower median incomes and lower educational attainment than the citywide average. They also contained fewer wetlands and were located farther from hospitals, potentially complicating both disaster response and long-term recovery. Residents in these areas were more likely to include people with disabilities, a factor that can make evacuation, access to warning systems and recovery from power outages or extreme temperatures more difficult. In addition, the most exposed neighborhoods had a higher proportion of non-white residents, highlighting the unequal distribution of environmental danger across the city.

The researchers connected this pattern to Portland’s history of redlining and uneven urban investment. Much of East Portland near today’s I-205 was classified as “definitely declining” in 1938 maps created by the Home Owners’ Loan Corporation, a federal program whose lending grades helped institutionalize racial discrimination in housing and finance. Areas marked as undesirable often received less investment in infrastructure, public amenities and economic development for generations. Later redevelopment in historically redlined but lower-risk neighborhoods in North and Northeast Portland contributed to rising housing costs. As those communities became less affordable, many residents were pushed toward East Portland, where housing was often cheaper but exposure to heat and flooding was greater. The movement of people, the researchers argue, is itself part of the hazard system.

This history also helps explain why hazard exposure cannot be reduced simply by building protective infrastructure in the places that currently appear most vulnerable. A new park, flood-control project or transportation improvement may make a neighborhood safer, but it can also increase property values and rents. Without anti-displacement measures, residents who endured years of environmental neglect could be priced out just as conditions begin to improve. Huber cautioned that planners must consider how ecological and technological changes influence where people live. “You don’t want to inadvertently cause people to move,” he said. The warning is increasingly relevant as cities invest in climate adaptation and compete for limited housing in neighborhoods with lower disaster risk.

The findings point toward a different model of urban resilience, one that treats natural infrastructure as part of public safety rather than as a decorative addition. Wetlands, tree canopies and other “blue” and “green” spaces can perform several protective functions at once. Wetlands can store floodwater, reduce downstream flows and support cooler local microclimates. Vegetation can provide shade and lower surface temperatures, although its effects on wildfire and slope stability depend on species, density, moisture and land-management practices. Trees may stabilize soil and reduce landslide potential in some settings, while in others dry or poorly managed vegetation can contribute to fire risk. These interactions illustrate why climate planning requires place-specific analysis rather than a universal solution.

Portland’s Foster Floodplain Natural Area offers an example of the type of intervention the study could help guide. In the Lents neighborhood, the city purchased property from more than 60 homeowners and restored space along Johnson Creek so the waterway could overflow safely and store floodwater. Such projects can reduce flood damage while creating habitat, open space and cooler environments for nearby residents. The new research suggests that similar investments should be prioritized according to combined hazard exposure and social vulnerability, with hospitals, evacuation routes and other critical infrastructure planned to remain functional during multiple simultaneous emergencies. As climate change intensifies heat waves, heavy rainfall and wildfire conditions, a map that shows only one threat at a time may no longer be sufficient.

The Portland study is intended to be replicated in other cities where climate hazards intersect with development pressures and inequality. Its central message is both technical and political: risk is produced by the interaction of natural processes, engineered systems and social decisions. A neighborhood’s vulnerability can rise when heat, flooding or fire converges with inadequate drainage, limited tree cover, distant medical care, low incomes and a history of exclusionary investment. By identifying those intersections before disaster strikes, city officials may be able to target green and blue infrastructure, improve emergency planning and protect residents from displacement. For Portland, the maps make a difficult reality visible: the communities facing the greatest number of hazards are often the same communities that have received the fewest resources to withstand them.

Subject of Research: Multi-hazard climate vulnerability in Portland, Oregon, including extreme heat, flooding, wildfires, landslides, social inequality and urban resilience.

Article Title: Spatial assessment of multi-hazard potential across scales using the social, ecological, and technological systems framework

Web References: https://link.springer.com/article/10.1007/s11069-026-08362-9; https://www.portland.gov/bes/protecting-rivers-streams/ffna; https://sites.google.com/pdx.edu/psunrt/home

References: Huber, Justin, and Heejun Chang. “Spatial assessment of multi-hazard potential across scales using the social, ecological, and technological systems framework.” Natural Hazards. DOI: 10.1007/s11069-026-08362-9.

Image Credits: Justin Huber and Heejun Chang, Portland State University

Keywords: climate change, natural hazards, Portland, Oregon, extreme heat, flooding, wildfires, landslides, environmental justice, redlining, urban resilience, wetlands, disaster planning, social vulnerability, climate adaptation

The study meticulously mapped hazardous sites, such as industrial waste facilities, Superfund sites, and toxic storage locations, alongside flood risk projections informed by recent climate models. The researchers combined geospatial data on hazardous locations from EPA databases with sophisticated projections of sea level rise and flooding scenarios under various greenhouse gas emissions trajectories. Their assessment revealed that thousands of hazardous sites currently imperiled by rising waters will expand dramatically by mid-century, placing nearby marginalized communities at exponentially greater risk of contamination from flooded toxic materials.

One profound revelation of the study is the clear spatial overlap between hazardous sites vulnerable to flooding and neighborhoods characterized by low income, high proportions of minority residents, and limited social capital. The authors demonstrated that communities historically burdened by systemic inequalities bear the brunt of environmental hazards exacerbated by climate change. This dynamic amplifies existing disparities in health outcomes, access to resources, and political representation, underscoring the need for intersectional climate resilience efforts.

Technically, the researchers utilized a multi-layer geospatial analytic framework integrating floodplain mapping under different Representative Concentration Pathway (RCP) scenarios. They incorporated LiDAR-derived elevation data, local hydrological models, and FEMA flood risk assessments refined with climate projections. This advanced modeling accounted for land subsidence, storm surge, and tidal variance, thereby yielding a nuanced understanding of site-specific flood vulnerabilities. Such an approach represents a significant technological advancement in environmental risk assessment methodologies.

Furthermore, the analysis highlighted that by 2050, under moderate emission scenarios, over 2,000 hazardous sites nationwide could face flooding, exposing an estimated 4 million people to potential toxic releases. Notably, the frequency and intensity of storm surges accompanying higher sea levels are projected to increase contaminant dispersion dramatically, suggesting that flood events will not only become more common but also more ecologically damaging. This nexus of factors paints a dire picture for public health if mitigation strategies are not swiftly and comprehensively implemented.

The authors emphasized the critical importance of coupling climate adaptation plans with environmental justice frameworks. They advocate for targeted investment in flood mitigation infrastructure—such as sea walls, coastal wetlands restoration, and improved stormwater management—specifically prioritized for vulnerable communities. Additionally, the study calls for the rigorous cleanup and remediation of hazardous sites before flood risks rise, aiming to prevent toxic exposure during inundation events. This strategy requires enhanced policy coordination between environmental protection agencies, urban planners, and marginalized community representatives.

Intriguingly, the research also identifies environmental racism patterns embedded in the siting of these hazardous facilities near marginalized communities. By tracing historic zoning policies and land-use decisions, the study illustrated that structural inequities have long predisposed certain populations to disproportionate environmental risks. The overlay of climate-driven flooding now threatens to make an already unjust legacy exponentially worse. Such insights compel a reevaluation of regional development and regulatory frameworks with equity at the forefront.

Moreover, the study’s approach incorporates socioeconomic vulnerability indices, integrating data on income, educational attainment, language proficiency, and health care access to quantify community resilience. This multi-dimensional perspective enables a richer understanding of which populations will be least equipped to respond to or recover from hazardous site flooding. For policymakers, these metrics provide crucial guidance for directing resources and emergency preparedness efforts where they are needed most.

From a technical standpoint, the paper advances coastal risk modeling by merging natural hazard exposure with anthropogenic contamination risk assessment. This dual-threat approach captures the compounded risks of climate change intersecting with legacy pollution, a frontier area in environmental health research. The authors suggest that this integrated framework can be adapted globally, to identify and mitigate hotspots of toxic flood risk in other vulnerable coastal megacities.

Importantly, the researchers also analyzed policy gaps in current hazardous site regulation and climate resilience efforts. They found insufficient incorporation of flood risk in hazardous waste management plans, noting that regulatory frameworks lack mechanisms to proactively address contaminant releases due to climate-driven flooding. This regulatory oversight represents a critical vulnerability that must be addressed through updated guidelines and stricter oversight to prevent future environmental and public health disasters.

The report also discusses the potential compounding effects of chemical exposures following floods, including increased groundwater contamination, bioaccumulation in local food webs, and adverse health outcomes such as respiratory illnesses, cancers, and neurological disorders. Vulnerable populations, including children, elderly, and those with pre-existing conditions, stand to suffer disproportionate impacts. The authors call for enhanced environmental monitoring and public health interventions in communities identified as at-risk.

Importantly, the study reveals that existing federal funding mechanisms and climate adaptation grants insufficiently prioritize hazardous site risk reduction in socially vulnerable areas. This funding gap undermines efforts to build long-term resilience and increases the likelihood of costly disaster response and remediation. Bridging this divide requires a paradigm shift towards justice-centered funding allocation and inclusive community engagement in resilience planning.

The researchers conclude with a compelling call to action, urging urgent collaboration across scientific disciplines, government agencies, NGOs, and affected communities to address these intersecting crises. Policy reforms, technological innovations, community empowerment, and rigorous monitoring must coalesce to mitigate the escalating risks of hazardous site flooding under sea level rise. Without decisive intervention, expanding floodwaters threaten to unleash hazardous contamination with profound implications for environmental justice, human health, and ecosystem integrity.

Ultimately, this study provides a sobering but necessary wake-up call. It lays bare how climate change exacerbates entrenched inequities through the perilous convergence of rising seas and toxic legacies. Its comprehensive dataset, robust analytic techniques, and stark findings equip stakeholders with the evidence base needed to forge an integrated response that honors both climate resilience and social equity imperatives. The health and dignity of marginalized coastal populations depend on heeding this urgent appeal.

In the unfolding narrative of climate impact science, this research marks a significant milestone. It demonstrates how advanced geospatial analysis combined with social vulnerability frameworks can illuminate hidden dimensions of risk and guide equitable adaptation strategies. As sea level rise accelerates globally, such innovative and justice-centered approaches will be indispensable for safeguarding vulnerable communities and securing sustainable, inclusive futures amid a changing ocean landscape.

Subject of Research: The study focuses on assessing the risk of sea level rise and flooding on hazardous sites located near marginalized communities across the United States, evaluating the compounded environmental and social justice risks posed by climate change-driven inundation of toxic facilities.

Article Title: Sea level rise and flooding of hazardous sites in marginalized communities across the United States

Article References:
Cushing, L.J., Ju, Y., Karasaki, S. et al. Sea level rise and flooding of hazardous sites in marginalized communities across the United States. Nat Commun 16, 9711 (2025). https://doi.org/10.1038/s41467-025-65168-2

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41467-025-65168-2