# Southern Ocean evidence for recurring West Antarctic Ice Sheet destabilization during Marine Isotope Stage 11

## TL;DR

The study finds evidence that the West Antarctic Ice Sheet melted repeatedly during a warm climate period, affecting ocean oxygen levels and sea levels.

## Contribution

The paper provides new evidence of recurring WAIS destabilization and its impact on deep ocean oxygen levels during MIS11.

## Key findings

- Bottom water oxygen minima in the Pacific Southern Ocean during MIS11 align with Atlantic events.
- WAIS retreat likely caused Antarctic Bottom Water perturbations and sea-level rise during MIS11.
- Ocean warming and deep circulation changes may have enhanced WAIS melting from below.

## Abstract

Millennial-scale deoxygenation of Antarctic Bottom Water (AABW) in the Atlantic Southern Ocean during past interglacials was linked to West Antarctic Ice Sheet (WAIS) melt-driven suppression of dense water formation along the Antarctic margin. However, the circum-Antarctic extent of these ‘AABW stagnation events’ and drivers of WAIS retreat remain unclear. Here, we identify recurring bottom water O2 minima in the central Pacific Southern Ocean during Marine Isotope Stage (MIS) 11 (424–374 ka ago) that are synchronous with their Atlantic Southern Ocean counterparts. As they (partially) align with Circumpolar Deep Water (CDW) warming above present-day levels and/or a reorganization of deep-ocean circulation, we postulate recurring and synchronized Pacific-Atlantic AABW perturbation events during MIS11 through WAIS retreat and enhanced exposure to ocean heat (i.e., CDW) from below. This indicates a significant contribution of WAIS meltwater to sea-level high-stands during MIS11 and, by analogy, to sea-level rise due to ocean warming in the future.

Recurring deep ocean oxygen minimum events occur in the Pacific Southern Ocean during the warm climate interval Marine Isotope Stage 11. They are linked with perturbed Antarctic Bottom Water formation caused by West Antarctic Ice Sheet retreat.