Sea-Level Change in Asia since the Last Glacial Maximum

Tanghua Li 

As a ‘far-field’ area, distal from former ice sheets, Asia is minimally influenced by the glacial isostatic adjustment process. Therefore, Relative sea-level (RSL) data from Asia, recorded by various geological proxies, provide essential constraints on the history of ice-equavilent sea-level changes. The global mean sea-level has risen over 130 m on average since the Last Glacial Maximum (LGM), significantly altering the paleogeography, landmass distribution, coastal evolution, ecosystems, regional climate and monsoon patterns, as well as the human settlement in the region. Understanding paleo RSL changes is crucial for projections of future sea-level rise and its potential impacts on Asia’s densely populated coastal regions.

This chapter introduces the controlling processes behind RSL changes, reviews available RSL proxies in Asia, and discusses the spatial and temporal variability of RSL history since the LGM. Particularly the mid-Holocene highstand, a unique phenomenon that RSL was higher than present-day levels between 7000 and 4000 years ago in the ‘far-field’ regons, will be illustrated in detail. The mid-Holocene highstand serves as a analogue for future sea-level rise of similar magnitude. This chapter also explores the impact of RSL rise on landmass and human demography, featuring a case study from Southeast Asia that integrates paleogeographic data and population genomics to reveal the earliest documented instance of forced human migration driven by sea-level rise. Additionally, the probability perspectives of future sea level for Singapore using geological proxies and instrumental measurements since the LGM is provided. It shows that the projected rate of sea-level rise by 2150 under a moderate emissions scenario has only been exceeded (at least 99% probability) during the rapid ice melting events.