Annual resolution records of sea-level change since 1850 CE reconstructed from coral δ18O from the South China Sea

Abstract

Compared with other ocean basins, annual resolution long-term series of sea-level records in the South China Sea (SCS) are still rare. Here we first analyzed the correlation mechanism between the oxygen stable isotopes (δ 18 O) of Porites coral and instrumental sea-level, sea surface salinity (SSS), sea surface temperature (SST) and rainfall of the SCS, and NINO 3.4 SST during 1980–2015 CE (Common Era); and we then quantitatively reconstructed sea-level at an annual resolution based on the coral δ 18 O in the SCS. The results show that the sea-level fell slightly (−0.73 ± 0.27 mm/yr) during 1850–1900 CE; then has continuously risen (1.31 ± 0.06 mm/yr) with a total increase of 152 ± 7 mm from 1900 to 2015 CE. On the inter-annual timescale, ENSO by mediating the overflow effect of seawater in the Western Pacific Warm Pool and the location of storm genesis in the western Pacific, indirectly affects sea-level, rainfall and SSS, which is finally reflected in changes in coral δ 18 O in the SCS. On the long-term timescale, especially since the 1900s, the gradual increase in SST and glaciers and ice sheets meltwater injected into the ocean due to the continuous warming mainly caused by human activities has not only promoted the rise of sea-level, but also caused a gradual negative bias of δ 18 O seawater (i.e. a gradual decrease of SSS), these processes are faithfully recorded by coral δ 18 O. Compared with SST, SSS or δ 18 O seawater may play a more important role in promoting the negative bias of coral δ 18 O in the SCS. Our study not only provides a better understanding of sea-level history and relationship mechanism around the SCS during 1850–2015 CE, but also may have the potential to provide a valuable proxy for the accurate quantitative reconstruction of sea-level at an annual resolution over a longer time scale for recent past periods. • On the interannual timescale, ENSO is the main driver of coral δ 18 O via its indirect effects on seawater δ 18 O in the SCS • On the long-term timescale, SST and injection of meltwater are the main driver of changes in coral δ 18 O and sea-level • Both SSS and SST are bridges between coral δ 18 O and sea-level • Coral δ 18 O is an ideal proxy to indicate sea-level, which has risen by 152 ± 7 mm in total from 1900 to 2015 CE in the SCS