Assessing sea level rise and extreme events along the China–Europe Sea Route

Abstract

The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report highlights the accelerating rise of global mean sea level (GMSL), with trends surpassing historical rates observed over the past two millennia. The China–Europe Sea Route (CESR), a region of strategic importance for international trade, is particularly vulnerable to sea level changes and extreme events. This study integrates data from satellite altimetry, tide gauge records, and a global hydrodynamic model to assess absolute and relative sea level variations, as well as extreme sea level events, across eight CESR sub-regions over the period 1993–2023. Statistically significant mean sea level trends confirm systematic decadal variability across regions. Notably, the East China Sea, Yellow Sea and Bohai Sea show a decadal trend slowdown in the second (2003–2013) and third decade (2013–2023) with respect to the first one (1993–2003). Signals of enhanced regional mean SLA trends are observed in the North Indian Ocean, while Pacific sub-regions exhibit pronounced decadal variability. Discrepancies between tide gauge and satellite altimetry in specific areas were attributed to land subsidence and inherent limitations of coastal altimetry. A global hydrodynamic model provided estimates of return periods for extreme sea levels, identifying high-risk zones such as the Bay of Bengal and the South China Sea. However, challenges remain in capturing cyclone impacts, emphasizing the need for continued improvements in modeling frameworks for extreme sea level assessment. By highlighting the importance of localized, data-driven approaches and continuous monitoring, the findings contribute to advancing climate resilience and informing risk mitigation strategies in this globally significant region.