Future Antarctic marine accessibility in a warming world

Abstract Antarctic sea ice is projected to decline under continued global warming, reshaping marine accessibility in the Southern Ocean with far-reaching implications for navigation, ecosystem stability, and polar governance. Leveraging optimally selected sea ice projections from the coupled model intercomparison project phase 6, we assess future Antarctic marine accessibility for open water and polar class 6 (PC6) vessels under 1.5 °C, 2 °C, and 3 °C warming scenarios. Results show significant increases in marine accessibility, with near-complete summer accessibility across the Southern Ocean in February, even under the 1.5 °C Paris Agreement target. Winter marine accessibility also increases, with over 50% of the Southern Ocean accessible for PC6 vessels at 3 °C warming. Spatially, the Eastern Route region, especially in the King Haakon VII Sea, is projected to exhibit the most significant increase in accessibility. Meanwhile, the South Shetland Islands and Antarctic Peninsula, which currently serve as important hubs for scientific research and logistical operations, are projected to experience increased year-round accessibility as global temperatures continue to rise. These findings provide insights that could support climate-smart marine spatial planning in the high seas.