A mid\u2011ocean polynya needs the cake to collapse. Salt must slip into the surface, make the top layer heavier, and flip the stack. <\/p>\n
Once that happens, convection kicks in, the lid fractures, heat pours skyward, and the ocean \u201cbreathes\u201d gases.<\/p>\n
Coastal versions manage something similar each year because fierce winds shove ice away from land. Out on the high seas, though, the phenomenon is much less common.<\/p>\n
Maud\u00a0Rise<\/a>, a\u00a04,600\u2011foot\u2011tall seamount, may provide the missing ingredient by diverting currents and trapping water in tight spirals.<\/p>\n Stubborn patch over Maud\u00a0Rise<\/p>\n History backs that hunch. Between\u00a01974 and\u00a01976, a much larger hole lingered over Maud\u00a0Rise each winter. <\/p>\n The Maud\u00a0Rise polynya was discovered in the 1970s, when remote\u2011sensing satellites capable of observing sea ice<\/a> over the Southern Ocean were first launched. <\/p>\n It persisted through consecutive winters from\u00a01974 to\u00a01976, and oceanographers at the time assumed it would become an annual occurrence. But since the 1970s, it has occurred only sporadically and for brief intervals.<\/p>\n \u201c2017 was the first time that we\u2019ve had such a large and long\u2011lived polynya in the Weddell Sea since the 1970s,\u201d said Aditya\u00a0Narayanan of the University of Southampton<\/a>, lead author of the study in\u00a0Science\u00a0Advances. <\/p>\n He joined colleagues to probe the comeback with robotic floats, tagged elephant seals, and a high\u2011resolution ocean model<\/a>.<\/p>\n Salt, storms, and a hidden conveyor<\/p>\n During those winters, the clockwise Weddell Gyre sped up. That spin drew a deep layer of warm, salty water nearer the surface, softening ice from below. Yet the meltwater should have freshened the lid and shut down mixing.<\/p>\n \u201cThis upwelling helps to explain how the sea ice might melt. But as sea ice melts this leads to a freshening of the surface water, which should in turn put a stop to the mixing,\u201d explained Fabien Roquet, a Professor in Physical Oceanography at the University of Gothenburg<\/a> and co-author of the research. <\/p>\n \u201cSo, another process must be happening for the polynya to persist. There must be an additional input of salt from somewhere.\u201d<\/p>\n Roaring extratropical storms supplied part of that punch. Their swirling winds flung sea ice outward and dragged briny water toward Maud\u00a0Rise. <\/p>\n Atmospheric rivers \u2013 plumes of moist air stretching a thousand miles \u2013 added warmth from above, helping strip away stratification.<\/p>\n \u201cEkman transport\u201d as the missing shove<\/p>\n A final push came from physics first described a century ago. When wind blows across the ocean, Earth\u2019s rotation deflects the surface flow roughly\u00a090\u00a0degrees, a process called Ekman transport<\/a>. <\/p>\n The model showed this flow steering salt\u2011laden water onto the northern flank of Maud\u00a0Rise, exactly where the 2017 hole opened. <\/p>\n \u201cEkman transport was the essential missing ingredient that was necessary to increase the balance of salt and sustain the mixing of salt and heat towards the surface water,\u201d said co\u2011author Alberto\u00a0Naveira\u00a0Garabato, also from the University of Southampton.<\/p>\n The storms didn\u2019t just move ice; they herded the right water into the right spot, letting convection roar. By late September, the opening had vented more than twenty times the heat that normally seeps through unbroken ice before finally freezing again.<\/p>\n Polynyas have a global impact<\/p>\n A hole in the Southern Ocean<\/a> sea ice may look local, yet its fingerprints show up far away. <\/p>\n \u201cThe imprint of polynyas can remain in the water for multiple years after they\u2019ve formed,\u201d noted Professor Sarah Gille from University of California San Diego (UCSD<\/a>), another co-author of the research<\/p>\n \u201cThey can change how water moves around and how currents carry heat toward the continent. The dense waters that form here can spread across the global ocean.\u201d <\/p>\n Deep convection hauls carbon\u2011rich water upward, where it can release CO\u2082, and sends newly formed, oxygen\u2011rich brine sliding along the seafloor.<\/p>\n What happens next?<\/p>\n That heavy brine eventually feeds the global conveyor belt of currents that helps regulate climate. Because the Maud\u00a0Rise mechanism hinges on a stronger gyre and stormier skies, its future frequency could ride on winds already shifting as the planet warms.<\/p>\n \u201cFor the first time since observations began in the 1970s, there\u2019s a negative trend in sea ice<\/a> in the Southern Ocean, which began around\u00a02016. Before then, it had remained somewhat stable,\u201d Professor Gille concluded.<\/p>\n The same rise of warm, salty water that primed the\u00a02017 hole now seems to be thinning ice across Antarctica\u2019s fringe.<\/p>\n Scientists will watch the next few winters closely. Whether the polynya returns or not, its story shows that the frozen edge of the world can still spring surprises \u2013 and that what happens far south seldom stays there, for the wider planet.<\/p>\n The full study was published in the journal Science Advances<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Antarctica\u2019s winter sea ice usually forms a bright lid over millions of square miles. So when a massive,…\n","protected":false},"author":2,"featured_media":39474,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3843],"tags":[728,70,16,15],"class_list":{"0":"post-39473","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-environment","9":"tag-science","10":"tag-uk","11":"tag-united-kingdom"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/114378363805382423","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/39473","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=39473"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/39473\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/39474"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=39473"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=39473"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=39473"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"An](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/04\/antarctica_sea-ice-hole_Maud-Rise-polynya_switzerland-size_blue-ice_credit-NASA_1s.webp.webp\")
<\/a>An arial view of the Maud Rise polynya. Scientists were baffled as to how this formed but now have an explanation. Click image to enlarge. Credit: NASA Earth Observatory<\/p>\n