Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

Abstract

The first moderate‐ to high‐resolution Holocene marine stable isotope record from the nearshore Antarctic continental shelf (Ocean Drilling Program (ODP) Hole 1098B) suggests sensitivity of the western Antarctic Peninsula hydrography to westerly wind strength and El Niño‐Southern Oscillation (ENSO)‐like climate variability. Despite proximity to corrosive Antarctic water masses, sufficient CaCO3 in Palmer Deep sediments exists to provide a high‐quality stable isotopic record (especially in the late Holocene). Coherence of benthic foraminifer δ18O, δ13C, sedimentologic, and CaCO3 fluctuations suggests that rapid (<20 years) Palmer Deep bottom water temperature fluctuations of 1°–1.5°C are associated with competitive interactions between two dominant oceanographic/climatic states. An abrupt shift from a warmer, stable Upper Circumpolar Deep Water (UCDW) state to a cooler, variable shelf water state occurred at ∼3.6 ka. Palmer Deep bottom waters oscillated between UCDW and shelf water‐dominated states between ∼3.6 and 0.05 ka. Cool shelf water intervals correlate with Neoglacial events, the most recent and largest being the Little Ice Age (LIA; ∼0.7–0.2 ka). Similarities between Palmer Deep and global Holocene records and the rapidity of inferred bottom water fluctuations suggest that western Antarctic Peninsula shelf hydrography has not been controlled by thermohaline reorganizations but by variable strength and/or position of the Southern Hemisphere westerly wind field. We suggest that these atmospheric perturbations may have originated in the low‐latitude tropical Pacific.