High interstadial sea levels over the past 420ka from the Huon Peninsula, Papua New Guinea

12 pages, 5 figures, supplementary information https://doi.org/10.1038/s43247-022-00583-7.-- Data availability: The Pleiades satellite imagery was obtained through the DINAMIS program of the Centre National d’Etudes Spatiales (CNES, France) under an academic license and is not for open distribution. We do however share the Digital Surface Model that was derived from the satellite imagery (Supplementary Data 5), in GeoTiff format with 2-m horizontal resolution, which is enough to reproduce the results of this study. We note that the original imagery could be requested through dinamis@cnes.fr (please quote this paper). The 12-m resolution TanDEM-X Digital Surface Model that is used in this study was also obtained under an academic license and not for open distribution. It is not necessary to possess this data in order to reproduce the results of this study: this data was only used for aesthetic purposes in some of the maps, and Supplementary Fig. 3. To freely obtain such data, we note that calls for scientific projects are regularly launched through the TanDEM-X Science website (https://tandemx-science.dlr.de/).-- Code availability: The code for reef modeling is available through https://github.com/Anne-Morwenn/REEF. The TerraceM-2 code for shoreline angle calculation is available through https://doi.org/10.3389/feart.2019.00255
The history of sea level across the Quaternary is essential for assessing past and future climate. Global sea-level reconstructions are typically derived from oxygen isotope curves, but require calibration with geological constraints that are scarce prior to the last glacial cycle (>130 thousand years ago). Here we show that the coral reef terrace sequence at the Huon Peninsula (Papua New Guinea) provides such constraints up to ∼420 thousand years ago, through a geometric analysis of high-resolution topographic data. We derive a northward tectonic tilt as regional deformation pattern, and estimate relative sea level for 31 Quaternary periods, including several periods for which no relative sea level data exists elsewhere. Supported by numerical reef models, these estimates suggest that oxygen isotope-based global mean sea-level curves systematically underestimate interstadial sea-level elevations, by up to ∼20 m. Compared to those curves, our results imply a stronger degree of non-linearity between ice-sheet volumes and global temperatures within Quaternary glacial cycles
G.G. acknowledges the CNES for his postdoctoral scholarship that made this study possible, as well as postdoctoral funding from the IRD and the Manajemen Talenta BRIN fellowship program
With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)