Waves alter Antarctic polynyas by breaking up surrounding sea ice

October 29, 2026 dialog Waves alter Antarctic polynyas by breaking up surrounding sea ice Sadie Harley Scientific Editor Robert Egan Senior Editor Polynyas are one of Antarctica's great counterintuitive features: recurring areas of open water surrounded by vast expanses of sea ice. These unusual environments are hot spots for sea-ice production, ocean–atmosphere exchange and biological productivity. They are commonly maintained by powerful winds that push newly formed ice away from the coast, repeatedly exposing the ocean to the freezing Antarctic atmosphere. Yet these strong winds do something else: they generate waves. This is hardly surprising. Wind blowing across open water generates waves, and coastal polynyas are no exception. However, despite this seemingly obvious connection, we have rarely considered how these waves might affect the surrounding sea ice. Our study published in Nature Communications shows that during extreme wind events, waves generated inside the Vincennes Bay Polynya in East Antarctica can become steep enough to fracture the surrounding sea ice from the inside out, triggering a series of feedback processes that alter the evolution of the polynya itself. An unexpected pattern in our observations Our original research had little to do with waves generated inside coastal polynyas. We were interested in how energetic waves originating from the Southern Ocean propagate through hundreds of kilometers of Antarctic sea ice, and deployed wave-measuring buoys on coastal landfast ice in East Antarctica to investigate this process. During several of our deployments, however, the ice carrying our instruments broke away from the coast, leaving the buoys drifting across the nearby Vincennes Bay Polynya. Each time this happened, we noticed a similar pattern in the measurements: wave heights increased considerably as the buoys moved into open water. Initially, these observations were incidental to our original research. But as the pattern repeated over several years, we began to appreciate how energetic waves generated within the polynya could become. This raised a question we had not originally set out to investigate: could these waves be large enough to break up the surrounding sea ice and influence the evolution of the polynya itself? Breaking and redistributing the ice When waves encounter a sea-ice cover, they cause the ice to bend as they propagate through it. If the resulting stresses become sufficiently large, the ice can fracture. Our analysis indicates that waves generated within the polynya can readily exceed the conditions required for breakup. Fracture is only the first part of the process. Once broken, a relatively connected ice cover becomes fragmented into smaller, more mobile floes. Strong winds continue to act on these fragments, while the waves themselves transfer momentum as they enter the ice cover. Together, these forces can transport and compact the broken ice downwind, sometimes causing individual floes to raft over one another. We found evidence of this larger-scale response in more than two decades of satellite observations. Following the most extreme wind-wave events, sea-ice concentration around the polynya decreased by up to approximately 30%, with the changes persisting for at least a week. Farther downwind, sea-ice concentration increased. This suggests that the ice was not simply disappearing. Instead, our observations are consistent with wave-induced breakup making the ice more mobile, followed by wind- and wave-driven redistribution of the fragments. Importantly, we did not observe comparable changes during similarly strong wind events when conditions were less favorable for wave generation, further supporting the role of waves in this process. The consequences extend beyond redistribution. Breaking up the ice exposes more open water to the cold Antarctic atmosphere, increasing new sea-ice production. Satellite observations support this interpretation, revealing larger areas of actively forming frazil ice following extreme events. In other words, locally generated waves can do more than fracture individual pieces of ice. They can influence the broader evolution of the polynya itself. The bigger polynya picture Our observations come from one coastal polynya, and the buoy crossings occurred during particularly strong wind events. How frequently these processes operate under more typical conditions, and how important they are elsewhere in Antarctica, remain uncertain. Nevertheless, strong winds are a defining feature of many Antarctic coastal polynyas, and several have comparable or larger stretches of open water over which waves can develop. This raises broader questions about how locally generated waves influence other Antarctic polynyas, and which combinations of wind, open-water extent and sea-ice conditions produce the greatest impact. These questions are particularly relevant as Antarctic coastal polynyas change. Previous research indicates that Antarctic polynyas have increased in size over recent decades. Larger areas of open water provide greater fetch, allowing locally generated waves more room to develop. Understanding how these environments evolve therefore requires considering not only the winds that maintain them, but also the waves those winds generate. This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate. Publication details Joey J. Voermans et al., Inside-outward breakup of sea ice by locally generated waves in the Vincennes Bay Polynya, Nature Communications (2026). DOI: 10.1038/s41467-026-77979-y Journal information: Nature Communications Dr. Joey Voermans is an expert in experimental oceanography at the University of Melbourne. His research focuses on ocean waves, air-sea interactions and Antarctic sea-ice dynamics, drawing on field observations from extreme marine environments to investigate the physical processes governing interactions between the ocean, atmosphere and sea ice.