A new multi-hazard analysis of twenty major U.S. coastal cities lays out a clear warning. Many of the nation’s largest population centers are more exposed, more vulnerable, and less prepared for coastal hazards than current public discussion reflects. The study’s findings are based on sea level rise, storm surge, erosion, land subsidence, high tide flooding, extreme rainfall, temperature extremes, drought, wind hazards, land use patterns, infrastructure concentration, and demographic factors. Taken together, the results point to accelerating stress on critical systems across the Gulf, Atlantic, and Pacific coasts.
The most direct signal comes from land elevation. Some cities are already operating almost entirely inside zones that fall below five meters of elevation. New Orleans sits at 99.56 percent exposure. Miami sits at 92.93 percent. Lake Charles sits at 92.30 percent. These conditions guarantee that any rise in water levels, whether from tides, storms, or long-term sea level trends, will reach key infrastructure, residential areas, and evacuation routes with little margin for error.
The study identifies Lake Charles, Louisiana as the highest-risk city in the entire assessment. It receives the top scores for hazard exposure because of fast relative sea level rise, frequent high tide flooding, intense rainfall, and regional storm surge risk. It also carries high exposure due to its geography and land use patterns. The city’s adaptive capacity is not strong enough to offset those combined pressures. The resulting composite risk places Lake Charles above New Orleans, Miami, and every other city in the dataset.
The hazard maps presented in the analysis show a sharp divide in sea level rise rates along the U.S. coastline. Gulf Coast locations commonly exceed four millimeters of annual rise, accelerated further by ongoing land subsidence. Similar trends appear along the Mid-Atlantic. The Pacific Coast shows lower rates on average, but still faces erosion, storm water issues, and drought. These regional differences are significant because they define how fast local exposure will increase before new defenses or land use adjustments are put in place.
High tide flooding is already a chronic problem for several cities. Boston records more than ten high tide flooding days each year even without storms. New Orleans shows similar numbers. These events disrupt transportation, damage roads, and cause repeated strain on drainage systems. The frequency of these floods is projected to increase, which means many locations will shift from occasional nuisance flooding to routine inundation that affects daily life and business operations.
Infrastructure vulnerability is one of the most serious findings in the report. The study documents the number of energy facilities, emergency shelters, roads, ports, and aerodromes built inside the lowest coastal elevations. New Orleans stands out with twenty-six power plants located in the flood zone and sixty-seven emergency shelters sitting in the same vulnerable area. Many cities show dense road networks placed in elevation zones that will flood under relatively minor water level increases. The concentration of critical systems in these areas creates the conditions for cascading failures. When roads, power, and shelters fail together, emergency response becomes significantly harder, and the consequences of a single event expand across a wider area.
The vulnerability analysis also highlights demographic factors. Cities with larger populations of older residents or very young children show higher susceptibility during evacuations and recovery periods. Land use in the lowest-elevation zones adds another layer of risk. Residential neighborhoods built directly in the exposure zone face greater displacement pressures. Natural vegetation in low zones is often limited, which reduces natural buffering against incoming water.
Socioeconomic capacity varies sharply across the twenty cities. Education levels, income, and the percentage of economically active residents determine how quickly a community can respond to and recover after major disruptions. Several Gulf Coast cities score lower in these categories. This creates a mismatch between hazard intensity and adaptive resources. Many of the cities facing the greatest physical hazards have fewer financial and institutional tools to manage those hazards. This gap increases long-term vulnerability and slows recovery after major events.
The scenario testing in the report shows what happens as water levels continue to increase this century. Under the range of sea level rise projections used in the study, cities diverge in their sensitivity. Some Gulf Coast cities show clear jumps in overall risk under moderate increases. Pacific Coast cities show smaller changes, though they still face other chronic hazards such as erosion and drought. Storm surge simulations reveal that risk can climb by four to five percent in several cities once storm categories rise, even under controlled model assumptions.
One of the most concerning results appears in the infrastructure analysis for low-elevation coastal zones. The report shows that infrastructure placement decisions made over several decades have placed power generation facilities, roads, ports, and even emergency shelters directly in the path of sea level rise and recurrent flooding. As land subsides in some regions, the effective rate of relative sea level rise accelerates, reducing the lifespan of existing protective structures and drainage systems. The study cites evidence that subsidence may contribute between twenty-three and thirty-five percent of total inundation by 2050 in parts of the Gulf Coast.
The comparison with FEMA’s National Risk Index reinforces the need for forward-looking models. FEMA’s index is based heavily on historic loss data, which does not always reflect the scale of future physical threats. Cities that have not experienced large recorded losses may appear safer in historical datasets, even though they now show rising vulnerability due to rapid coastal change, population growth, and infrastructure placement. The study’s multi-hazard index captures these emerging trends, showing why some cities are moving into higher-risk territory even without recent major disasters.
The overall conclusion is clear. Coastal risk in the United States is increasing through the combined effect of rising water levels, frequent flooding, concentrated infrastructure, demographic pressures, and varied adaptive capacity. The geographic distribution of this risk is uneven. Gulf Coast cities face the fastest changes and the most severe combined hazards. Atlantic cities face chronic flooding, aging infrastructure, and high population densities. Pacific cities show lower sea level rise trends but deal with drought, erosion, and specific localized risks.
The data shows that many coastal cities are moving toward conditions where hazards will cause larger and more frequent interruptions to power, transportation, housing, and emergency systems. This creates a growing gap between the speed of environmental change and the pace of local planning and infrastructure adaptation. The study provides evidence that this gap is widening in several cities where exposure is already high and adaptive capacity is limited.
Source:
Multi-Hazard Risk Index study, International Journal of Disaster Risk Reduction (2026).
Link: https://doi.org/10.1016/j.ijdrr.2026.106023
