New Controls on Sedimentation and Climate in the Central Equatorial Pacific Ocean

Abstract. The equatorial Pacific is a nexus of key oceanic and atmospheric phenomena, and its regional climate has critical implications for hydroclimate, the partitioning of CO₂, and temperature on a global scale. The spatial complexity of climate signals across the basin has long posed a challenge for interpreting the interplay of different climate phenomena including changes in the Intertropical Convergence Zone (ITCZ) and El Niño Southern Oscillation. Here, we present new, millennially resolved sediment core chronologies and stable isotope records from three sites in the equatorial Pacific’s Line Islands region, as well as updated chronologies for four previously studied cores. Age constraints are derived from ¹⁴C (n=17) and δ¹⁸O (n=610), which are used as inputs to a Bayesian software package (BIGMACS) that constructs age models and uncertainty bounds via correlation with the global benthic δ¹⁸O stack (Lee et al., 2023). We also make use of the new planktonic δ¹⁸O data to draw inferences about surface water salinity and to infer a southward-shifted position for the ITCZ at the Last Glacial Maximum (18–24 ka) and Marine Isotope Stage 6 (138–144 ka). These new chronologies and related datasets improve our understanding of equatorial Pacific climate and show strong promise for further surface and deep ocean paleoclimate reconstructions over the last several glacial cycles.