The ocean around Antarctica plays a critical role in sea level rise, sea ice, ecosystems and global climate. Yet many of the processes that control its behaviour, such as dense water cascades, coastal polynyas and circulation beneath ice shelves, occur at small scales and in places that are extremely difficult to observe. These small-scale processes are also poorly represented in climate models.
In this talk, I will show how a new generation of high-resolution ocean and sea ice models is transforming our understanding of the ocean around Antarctica. Drawing on recent Australian advances, I will explore how these models are revealing the formation, variability and pathways of Antarctic Bottom Water, which ventilates the deepest layers of the global ocean. I will show how models can also open new avenues for observing previously inaccessible processes, including by demonstrating that dense water flowing into the abyss leaves a surface signature that can be monitored from satellites. Beyond the physical climate system, these models can reveal how ocean currents connect Antarctic ecosystems and may transport invasive species towards the continent. Finally, I will present new projections from a model that explicitly represents the ocean cavities beneath Antarctic ice shelves. These simulations reveal strongly contrasting regional responses to future warming, including reduced grounding-line melt beneath cold ice shelves but rapid ocean warming and a fivefold increase in melt in West Antarctica.