Siple Dome vs Palmer Deep: Resolving a Dichotomy in Antarctic Holocene Paleoenvironmental Records from Marine Sediments and Ice Cores

We compare the detailed Holocene signals preserved in a northern Antarctic Peninsula marine sediment core (Palmer Deep at 64° S) to a similarly resolved Holocene ice core from the interior of the West Antarctic region (Siple Dome at 81° S). This exercise is done in order to decipher Holocene climate variability from contrasting sectors of the Southern Hemisphere that today lie on either side of the atmospheric contrast established by the circumpolar westerlies and the higher latitude circulation of the polar vortex. The records are remarkable for the agreement in the millennial scale frequency (first order) change exhibited at the half cycle of regional solar insolation (as controlled by precessional index). However the two signals are out of phase through the Late Holocene: with the Siple Dome record demonstrating increased melt events (summer warming) through the Late Holocene since 3.5 ka and Palmer Deep demonstrating lower productivity and mass accumulation (cooling) since 3.4 ka. Superimposed upon this millennial time scale change are multi-century events of short duration that demonstrate increased frequency in both records during the last 3.5 ka. If the Palmer Deep signal is faithfully interpreted from the proxy data then the contrast demonstrated between the two records confirms the persistence of the polar vortex vs. westerly circulation pattern back through the entire Holocene record. Concurrence of the Palmer Deep record with sea surface temperatures from the ACC-Peru Chile current supports this hypothesis.