West Antarctic Ice Sheet dynamics controlled export production in the Pacific Southern Ocean over the last 500,000 years

The increased supply of the micronutrient iron (Fe) promotes primary and export production in the Fe-limited Southern Ocean, which acts as a dynamic sink of atmospheric CO₂ that has amplified past natural climate variations. This mechanism critically relies on the partial dissolution of the lithogenic particle input. However, the influence of lithogenic particle composition (and Fe solubility) on Southern Ocean export production in the large Antarctic Zone (AZ) is largely unconstrained for the Pleistocene glacial cycles. Here, we present a comprehensive dataset of glacial-interglacial particle fluxes and geochemical composition in the remote Southeast Pacific AZ covering the last 500,000 years. The observed high fluxes and compositional range of lithogenic material can only be explained by sediment input sourced from West Antarctica. Importantly, higher solubility of the lithogenic input corresponds with enhanced export production, implying that West Antarctic Ice Sheet (WAIS) dynamics controlled the primary production in large parts of the South Pacific AZ. These processes contributed to atmospheric CO₂ reductions in particular during the early part of the glacial cycles, suggesting that the WAIS retreat will likely affect predictions of future changes in Southern Ocean biogeochemical cycles.