The impact of climate change and localized land subsidence along the Korean Peninsula Coastline: An Overview of future coastal inundation and vulnerability

• Overview of localized VLM, RSLR, and coastal vulnerability in South Korea. • First comprehensive evaluation of VLM across the coastal region of South Korea. • PS-InSAR-based VLM shows that low-lying coastal regions subsiding at an average rate of −0.94 mm/yr. • Coastal vertical resilience (C VR ) indicates elevation loss relative to sea-level rise at most PS-InSAR-VLM sites. • Coastal communities are increasingly vulnerable to hazards and climate change impacts. Urban metropolises in low-lying coastal regions are particularly vulnerable to inundation due to localized ground subsidence and relative sea level rise (RSLR), amplified by climate change. Thus, vertical land movement (VLM) is a pivotal factor in projecting RSLR, especially at regional and local scales over short to medium timeframes. However, VLM is difficult to calculate due to the scarcity of long-term dense instrumental records (e.g., GPS, tide gauges). Consequently, RSLR projections often neglect local VLM, introducing significant uncertainties in coastal hazard assessments and mitigation strategies, particularly in regions experiencing rapid SLR rates, like the South Korean coastal region. To address this, the multi-temporal Sentinel-1 SAR data (2017–2023; n = 402) were analyzed using advanced PS-InSAR technique to model land subsidence in South Korea’s low-lying coastal regions. The updated RSLR projections indicate that the integration of localized subsidence with the geocentric sea-level rise presents a more immediate and severe threat to low-lying coastal regions under IPCC AR6 low and high emissions scenarios. The land use/land cover (LULC) exposure analysis to land subsidence reveals that subsidence significantly exacerbates the vulnerability of coastal built-up and wetland regions to RSLR. The calculated coastal vertical resilience (C VR ) shows that most of the persistent scatterer points (PSPs) lose elevation relative to SLR, and more than 90 % of PSPs located along the low-elevated (MSL < 5 m) coastal region of South Korea are vulnerable. The findings highlight the importance of high-resolution localized VLM to address coastal deterioration and safeguard the infrastructure of the major metropolitan coastal cities from the impacts of future coastal inundation.