Vertical Land Motion and Coastal Cities: Bridging Global Science and Policy for Resilient Communities

Vertical land motion (VLM) is an underrecognized hazard in susceptible coastal cities, especially those experiencing rapid urbanization. Human-induced VLM often causes elevation loss (subsidence) at rates that exceed, sometimes by an order of magnitude or more, those of climate-driven sea-level rise. Local land subsidence (LLS) also damages infrastructure, disrupts drainage, and alters flood dynamics, yet its broader impacts remain poorly quantified and systematically assessed. This review synthesizes the scientific, technical, and policy dimensions of VLM, with particular focus on LLS, highlighting how natural processes and human activities interact to amplify coastal hazards. We examine the geophysical drivers of VLM, advances in monitoring and modeling, and their integration into hazard assessment frameworks. We consider socioeconomic and infrastructural vulnerabilities of city residents, especially where limited observational capacity and governance gaps intensify risk. VLM acts as both a physical amplifier and a socio-institutional blind spot within coastal adaptation planning, requiring real-time data integration, scenario testing, and inclusive policy development. Finally, we identify key research frontiers—including subsidence mitigation strategies, dynamic VLM projections, and equitable, high-resolution risk assessment—to support more resilient, adaptive, and just coastal futures. ▪ Tectonics, sediment compaction, groundwater extraction, and urban loading combine to produce complex, nonlinear patterns of vertical land motion that shape local hazard dynamics. ▪ Local land subsidence, often exceeding the rate of global sea-level rise, is the dominant and least understood driver of coastal flooding and infrastructure risk in many urban regions worldwide. ▪ Subsidence disproportionately affects marginalized communities, exacerbating social inequities, driving displacement, and eroding cultural heritage, underscoring the need for inclusive, justice-centered adaptation frameworks. ▪ Closing critical data and policy gaps through coordinated vertical land motion observation, open-access standards, and equitable governance is essential to safeguard coastal populations and sustain long-term urban resilience.