Early-mid Holocene Ross Sea extreme wave heights reflect sea ice retreat and ocean-atmosphere interactions.

Antarctic coastal systems preserve valuable records of postglacial environmental change and extreme storm events. On Inexpressible Island, Ross Sea, we integrated geomorphic mapping, boulder measurements, exposure dating, radiocarbon constraints, and hydrodynamic analysis to reconstruct early to mid-Holocene storm-wave activity. Here we show that between approximately 8000 and 5000 years ago, reduced sea-ice cover, expanded open-water fetch, and stronger atmosphere-ocean coupling drove repeated high-energy storms with significant wave heights of 1-3 m during typical events and up to 4-9 m during episodic extremes. These storms transported meter-scale boulders and formed raised beach ridges, the highest ridge crest situated at 29 m above sea level (asl), reflecting postglacial sea-level fluctuation, glacio-isostatic adjustment, and local wave energy variations. Holocene storminess in the Ross Sea region exceeded present-day extremes, underscoring linkages between Antarctic coastal evolution and climate-ocean-cryosphere processes, with implications for projecting future coastal change under ongoing warming.