New constraints on sea levels since the Last Glacial Maximum derived from the Atlantic coast of Africa and Southeast Asia

Reconstructions of relative sea-level (RSL) change from far-field regions (i.e., located far from extinct ice sheets) since the Last Glacial Maximum (LGM) provide fundamental constraints to global ice volumes. Most published sea-level records are temporally restricted to the Holocene (last ~11.7 ka BP) with very few extending to the LGM. Here, we present two new databases that quantify the magnitudes and rates of sea-level changes along the Atlantic coast of Africa and Southeast Asia from the LGM to present.

•  (1) Along the Atlantic coast of Africa, we compiled a database of 341 sea-level index points. During the LGM, RSL progressively dropped from -99.4 ± 2 m at 26.7 ± 0.5 ka BP to -103.0 ± 0.8 m at 19.9 ± 0.8 ka BP with average rates by -1 mm/yr. From ~15 to ~7.5 ka, RSL show phases of major accelerations with rates up to ~25 mm/yr, the timing of which is non-coincident with the Meltwater Pulse 1B and a major deceleration triggered by the ~8.2 ka cooling event. In the mid to late Holocene, data indicate the emergence of a sea-level highstand, which varied in magnitude (0.8 ± 0.8 to 4.0 ± 2.4 m above present mean sea level) and timing (5.0 ± 1.0 to 1.7 ± 1.0 ka BP).
• In Southeast Asia we compiled a database of 113 sea-level index points from the Sunda Shelf and Singapore. RSL rose from a lowstand of −121.1 m at 20.7 ka BP to −112.3 m at ~19 ka BP at rates of RSL rise up to ~7 mm/yr. Between ~16 ka and ~13 ka BP, RSL rose to −70 m with a cluster of SLIPs associated with the Meltwater Pulse 1A. The average rate of RSL rise reached ~15 mm/yr. In the Holocene RSL rose from −20.6 m at 9.4 ka BP to −0.25 m at ~7 ka BP at a maximum rate of 15 mm/yr. The rate of RSL rise subsequently slowed as RSL continued to rise and reached a mid-Holocene highstand of ~4.6 m at 5.2 ka BP. SLIPs constraining the mid- to late-Holocene transition suggest RSL fell below present level to −2.2 m between ~2.5 and ~0.25 ka BP at a rate of −1 mm/yr.