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 critical acceleration of global mean sea level (GMSL) rise, 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 satellite altimetry, tide gauge records, and advanced hydrodynamic models 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 consistent and systematic changes in sea level trends by decade and across regions. Notably the East China Sea, Yellow Sea and Bohai Sea show a decadal trend slowdown in the second (2003–2023) and third decade (2013–2023) with respect to the first one (1993–2003).

Accelerated regional mean SLA trends are observed in the North Indian Ocean, while Pacific sub-regions exhibited decadal variability. Discrepancies between tide gauge and satellite data in specific areas were attributed to land subsidence and inherent limitations of coastal altimetry.

Numerical modeling using the Global Tide and Surge Model (GTSM) 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 improved modeling frameworks.

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.