Profound modern sea-level evolution against geological backdrop in southeastern China

Quantifying the physical mechanisms driving relative sea-level change—including global mean sea level (GMSL) and its regional and local components (i.e., sea level budget)—is essential for reliable future projections and effective coastal management. While previous research has focused on sea-level budgets for China from late 20th-century, these studies capture short timescales and lack the long-term context necessary to fully assess modern sea-level rise. Here, we employ a spatiotemporal hierarchical model to reconstruct process-related Holocene sea-level budget (11700 BP to present) across different spatiotemporal scales in southeastern China. By integrating geological proxies, tide gauge records, and paleoenvironmental data, our finding show that while deglacial land ice melt-induced GMSL dominated the overall Holocene sea-level budget, its stabilization since the late Holocene (~4300 BP) has shifted the primary drivers to location-dependent regional processes, such as glacial isostatic adjustment and climate variability. This stability was disrupted in the mid-19th century by accelerating GMSL rise; it is extremely likely (P>0.95) that the GMSL rise rate since 1900 CE (1.51 > 0.16 mm/yr, 1σ) has exceeded any century over the past four millennia. Moreover, our geological analysis indicates that at least 94% of the rapid modern urban subsidence is attributable to anthropogenic activities, significantly amplifying local sea-level rise, with localized rates often exceeding the GMSL rise rate. These results highlight the profound modern sea-level evolution against its geological backdrop in southeastern China and emphasize the urgent need for city-specific, adaptive risk management strategies to address the pronounced spatial variability in the sea-level budget.