As the relentless advance of climate change continues to reshape the planet, one of the most pressing challenges humanity faces is the rising sea level. The gradual yet inexorable increase in ocean waters threatens not only ecosystems but also the very infrastructure that supports human civilization. A groundbreaking study recently published in npj Urban Sustainability provides a comprehensive assessment of the exposure of buildings across the Global South to long-term sea level rise, revealing unsettling insights about the vulnerability of urban infrastructure in some of the world’s most rapidly developing and densely populated regions.
The research, led by Willard-Stepan, Gomez, Cardille, and others, dives deep into the intersection of urban expansion, economic development, and environmental change. Unlike previous studies that often focused on developed countries with robust data collection mechanisms, this study extends its analytical reach to include cities and towns in the Global South, where data scarcity and rapid urbanization compound risks. By leveraging novel satellite imagery, geospatial modeling, and demographic data, the authors provide an unprecedented spatially explicit evaluation of how rising seas will affect millions of structures presently standing in vulnerable coastal zones.
Sea level rise is a product of multiple climate-related processes, including the thermal expansion of oceans and the melting of polar ice sheets and glaciers. The authors emphasize that projections for the 21st century and beyond show a consistent upward trend that will accelerate as global temperatures continue to rise. In this context, the study’s projections for how this rise affects urban infrastructure are crucial. Buildings, roads, and other critical assets are often located in low-lying coastal areas due to historical trade routes, economic opportunities, and population pressures, creating a perfect storm of risk as the shoreline shifts inland.
The study notably engages with the uncertainty inherent in sea level projections by incorporating multiple emissions scenarios and time horizons, from mid-century benchmarks to the year 2100 and beyond. This nuanced approach allows planners, policymakers, and researchers to envision a spectrum of possible futures rather than a single deterministic outcome. For cities in the Global South, where adaptation resources may be limited, understanding this range is vital to formulating responses that are both effective and equitable.
One of the most striking revelations from the research is the sheer number of buildings located within zones that are expected to be regularly inundated by high tides and storm surges in coming decades. Urban centers that are often seen as engines of economic growth—metropolises like Mumbai, Lagos, and Jakarta—face a difficult balancing act between pursuing development and mitigating risks associated with their geographical vulnerability. The authors highlight that while some coastal defenses exist, they are frequently insufficient or poorly maintained, accentuating the exposure.
An especially poignant aspect of the study lies in its examination of informal settlements, which frequently inhabit the most vulnerable coastal edges. These communities, often lacking secure tenure or access to infrastructure, suffer disproportionately from environmental hazards. The data suggests that millions of low-rise, often self-built structures are at imminent risk, raising concerns about displacement, loss of livelihoods, and long-term socio-economic destabilization.
The technical backbone of the study integrates remote sensing datasets with building footprint analyses and elevation models refined through machine learning techniques. This multidimensional spatial data fusion creates a high-resolution mosaic that identifies not only which buildings are at risk but also their construction type, height, and associated land use. Such technical sophistication is essential for tailoring interventions, as it provides granular insight into the vulnerability profile of urban environments at a scale previously unattainable in the Global South.
Moreover, the researchers engage with the temporal dynamics of exposure, recognizing that the risk is not static but accelerates over time as sea levels rise and urban footprints expand. This interplay suggests that new construction in hazardous zones without adequate protective measures may exacerbate future losses. Their findings underscore the urgent need for integrating climate risk assessments into urban planning, zoning policies, and development financing.
Water management and flood defense strategies in many evaluated cities appear insufficient to cope with projected rise and variability. Traditional “hard” infrastructure approaches such as seawalls and levees often face limitations, including costs, ecological disruption, and maintenance challenges. The paper advocates for a paradigm shift towards “nature-based” solutions, including wetland restoration and mangrove reestablishment, which offer adaptive capacity while preserving biodiversity and ecosystem services.
Financial vulnerability compounds exposure; many at-risk urban areas in the Global South fall within lower and middle-income countries where resources for resilient infrastructure and disaster response are constrained. This fiscal reality elevates the stakes of the authors’ call for international cooperation and targeted investment in climate adaptation that prioritizes equity and sustainability.
The study’s authors further stress the importance of community engagement and local knowledge in building adaptive capacity. Top-down technical solutions without local buy-in may falter in addressing the socio-economic complexities involved. Therefore, co-designed approaches that empower vulnerable populations can enhance resilience by combining scientific insights with lived experience.
In addressing data limitations, the paper’s methodologies demonstrate how innovative computational techniques can overcome gaps and uncertainties common in urban and environmental datasets in the Global South. This represents a significant step forward in the equitable distribution of knowledge and technological tools necessary for global climate adaptation.
Crucially, the researchers do not shy away from confronting the implications of potential widespread displacement and migration provoked by inundation of urban coastal zones. Such phenomena could lead to social disruption, increased urban density inland, and new environmental pressures elsewhere, creating cascading effects that extend far beyond the immediate zones of exposure.
Their projections challenge global decision-makers to recognize that climate risk is not uniform but intricately tied to socio-economic and geopolitical contexts. The study advocates for proactive collaborative frameworks that integrate climate mitigation, urban development, and disaster risk reduction into cohesive strategies that transcend national borders.
As urban populations around the world burgeon, particularly in coastal cities of the Global South, this research acts as a clarion call to action. The interdependence between environmental stability and urban sustainability is highlighted with unprecedented clarity, emphasizing that rising seas threaten not only ecosystems but also the foundation of modern civilization itself.
By combining rigorous technical analysis with a humanitarian lens, this study charts a way forward to safeguard vulnerable urban territories. It elucidates that addressing long-term sea level rise exposure is not merely an environmental imperative but a multidimensional challenge that necessitates integrated scientific, social, and political solutions.
The findings underscore that efforts to decelerate climate change, while critical, must be coupled with adaptive innovations tailored to the local realities of the Global South’s urban landscapes. Failure to act decisively risks locking in decades of vulnerability that may manifest in tragedies for both people and places.
Ultimately, the study by Willard-Stepan and colleagues offers an invaluable resource and roadmap for urban planners, climate scientists, policymakers, and civil society organizations striving to navigate the uncertain waters ahead. Their work exemplifies how interdisciplinary collaboration and cutting-edge technology can illuminate paths toward resilience amidst the daunting challenge of sea level rise.
Subject of Research: Exposure of buildings to long-term sea level rise across the Global South and associated urban vulnerability.
Article Title: Assessing the exposure of buildings to long-term sea level rise across the Global South.
Article References:
Willard-Stepan, M., Gomez, N., Cardille, J.A. et al. Assessing the exposure of buildings to long-term sea level rise across the Global South. npj Urban Sustain 5, 72 (2025). https://doi.org/10.1038/s42949-025-00259-z
Image Credits: AI Generated
