A research vessel sent to study ocean currents near Antarctica was pushed off course by a storm and stumbled upon something no one had expected: a previously unknown island, hidden behind thick, shifting sea ice. The discovery was made by the Polarstern expedition, operated by Germany’s Alfred Wegener Institute. The mission was focused entirely on studying ocean currents, sea ice behavior, and meltwater flow from the Larsen Ice Shelf. But when a dangerous storm forced the ship away from its planned route, the crew spotted a solid rock landmass that had gone unnoticed for years.
Once the scientists realized what they were seeing, they carefully maneuvered the vessel to within about 150 meters of the newly discovered land. They carried out the first detailed survey of the area using a multi-beam echo sounder to create a high-resolution map of the seafloor and shoreline, and used aerial drones to capture images from above. The reason the island had remained hidden for so long becomes clear when looking at the conditions in the region. Sea ice around the western side of the continental shelf near Joinville can reach up to 4 meters thick in some areas, driven by strong tidal movements and the island’s close proximity to the coast.
A real landmass could remain concealed behind or beneath thick, constantly shifting ice for years, with passing ships and even satellites mistaking it for an iceberg or an unclear patch of pack ice. But this discovery points to something much bigger happening across the wider Antarctic Peninsula today. It is not simply about one hidden island—it offers another look at how much this part of the world has been changing and how quickly. The Antarctic Peninsula is one of only three places on Earth that has experienced some of the most extreme warming over the past 50 years, with average temperatures rising at nearly five times the global average.
This continued warming has caused about 87% of the glaciers along the peninsula to retreat, along with the collapse of some of the largest floating ice shelves ever directly observed by scientists. The hidden island is only the most visually dramatic part of a much larger and stranger story. Scientists are also getting an unprecedented look at what lies beneath the ice sheet itself using advanced tools that allow them to effectively see through kilometers of solid ice. Published in the journal Nature Geoscience, a team of researchers announced the discovery of a massive, previously unknown geological structure buried beneath the East Antarctic ice sheet, with parts of it sitting under more than 3 kilometers of solid ice.
What they found was not a single feature but an enormous fan-shaped network made up of basins, deep depressions, and connected bedrock. This network revealed that several well-known subglacial features scientists had already identified individually were actually part of one single connected geological formation—something nobody had previously linked together. Researchers now believe this entire network developed through several different tectonic events connected to the formation and eventual breakup of Gondwana, the ancient supercontinent that once brought together what are now Antarctica, Africa, South America, Australia, and India. Buried beneath miles of Antarctic ice is a fossilized record of one of the most important geological events in the planet’s history—the physical marks left behind when an entire supercontinent broke apart.
This massive structure remained almost completely hidden until researchers combined radar, gravity, and magnetic survey data to finally reveal the full shape of what had been buried beneath the ice. The shape of the bedrock beneath an ice sheet plays a major role in controlling how the ice moves, where it flows quickly, and where it remains firmly anchored to the ground. In some cases, it can also determine how vulnerable certain sections of an ice sheet become when warmer water reaches them and begins weakening the ice from below. This newly revealed network of deep basins gives scientists a much clearer picture of the hidden landscape, helping them refine computer models used to predict how East Antarctica—the largest and until recently considered one of the most stable parts of the ice sheet—might respond as ocean and air temperatures continue to rise.
Another equally striking piece of research focused on how warm ocean water manages to reach and slowly erode ice shelves from underneath, quietly and invisibly long before any major change becomes obvious from the surface. Ice shelves are huge floating extensions of glaciers that help slow down the movement of enormous amounts of ice into the ocean. Scientists in Norway have now identified a process that could be causing these ice shelves to weaken faster than expected. According to the study, long channels carved into the bottoms of these ice shelves can trap relatively warm ocean water, causing much more melting in specific areas.
The findings raise concerns that go far beyond Antarctica. As ice shelves become thinner and weaker, they gradually lose their ability to hold back the glaciers behind them. This can allow more land ice to flow into the ocean, potentially speeding up global sea level rise. The research focused on the Fimbul Ice Shelf in East Antarctica, where scientists discovered that the shape of the underside of the ice shelf has a strong effect on how seawater moves beneath it.
Where deep channels exist underneath the ice, ocean currents can create small circulation patterns that trap warmer water against the ice instead of allowing it to move away quickly. Lead author Tore Hattermann from the IC3 Polar Research Hub in Tromsø, Norway, explained: “We found that the shape of the ice shelf underside is not just a passive feature. It can actively trap ocean heat in exactly the places where extra melting matters most. ”
The Fimbul Ice Shelf is located in East Antarctica, a colder part of the continent that has generally been considered less vulnerable than other regions.
Yet the researchers found that even small amounts of warmer water can substantially increase melting within the channels. The researchers found that melting inside these channels can increase by roughly an order of magnitude in some places. Co-lead author Chunguo Cui added that even modest inflows of warmer deep water can have a large effect when the base of the ice shelf is shaped by channels. This means some ice shelves that scientists usually consider cold may actually be more fragile than expected.
The team combined a highly detailed map of the underside of the Fimbul Ice Shelf with a high-resolution computer model of the ocean cavity beneath it. They tested both smoother ice shelf bases and more realistic channeled formations under cooler and slightly warmer ocean conditions, allowing them to separate the effects of the channels on ocean circulation, mixing, and melting. Antarctica has more than 70 ice shelves that extend the continent’s enormous ice sheet out over the surrounding ocean, covering about 1. 5 million square kilometers.
These ice shelves float on the water, meaning they do not directly raise global sea levels when they melt. However, if rising ocean temperatures cause them to melt from underneath, the ice shelves could become unstable, allowing the ice sheet behind them to flow faster into the ocean. The continent’s most vulnerable regions alone contain enough ice to raise sea levels by about 15 meters if all of it were to melt. A new research effort brought together computer modeling work on basal melt rates from nine different research groups around the world.
By combining the nine different models, researchers estimated that in recent decades, Antarctica’s ice shelves have lost about 843 billion tons of ice every year because of melting from underneath. To put that amount into perspective, it is equal to 843 giant ice cubes, each measuring 1 kilometer long, 1 kilometer wide, and 1 kilometer deep, all melting every year. It is also roughly the same amount of water that flows from the Nile River into the ocean each year. The results of this analysis, which took a decade to bring together, could help scientists improve and update their models for the future.
One detailed analysis of Antarctica’s entire ice sheet found that overall satellite data showed the continent lost about 93 billion tons of ice between 1992 and 2020. At the surface of the ocean, seawater freezes at around -1. 9°C. But beneath an ice shelf, where the water can be a kilometer or more below the surface, the pressure changes the freezing point, meaning the ocean water does not freeze until about -2.
2°C. The coldest water anywhere in the ocean is found beneath the Antarctic ice shelves. “There is no light,” said Dr. Steve Rintoul, an oceanographer and leading Antarctic expert at Australia’s CSIRO.
“All our usual tools for measuring the ocean cannot reach this water. Satellites cannot reach it because it is covered by ice. Ships cannot get in. ”
Only a small number of holes have ever been drilled through Antarctic ice shelves, and they can only provide information about conditions in one specific location.
But Rintoul’s team received an unexpected opportunity. Scientists placed an autonomous floating instrument called an Argo float underneath the Totten Ice Shelf, but the instrument drifted away and spent 9 months underneath two other ice shelves that were more than 300 meters thick. The data collected by the float showed that one of those ice shelves, the Denman Ice Shelf, was being exposed to warm water that was melting the ice from underneath. Rintoul says the Denman Glacier catchment contains enough ice to cause about 1.
5 meters of global sea level rise if it were completely lost. Its shape is such that once it passes a certain point, it can begin retreating in an unstable way without needing any additional influence from the ocean. In the distant geological past, when Earth was covered by much more ice than it is today, glaciers in Antarctica carved enormous canyons into the landscape as they expanded. “They were basically creating the conditions for their own collapse because those deep channels give warm water a path to move underneath the ice,” Rintoul said.
Ice loss from Antarctica is also producing huge amounts of fresh meltwater at a rate of around 1,100 to 1,500 billion tons every year. This meltwater eventually flows into the Southern Ocean and mixes with the seawater, making the ocean fresher. As the Southern Ocean becomes fresher, its different layers become more separated and stable. These changes are causing the upper part of the ocean circulation to become stronger, speeding up the movement of major ocean currents.
At the same time, the lower part of the circulation is becoming weaker because it depends heavily on the very salty Antarctic bottom water. Since the 1970s, the upper part of the circulation has strengthened by about 3 to 4 sverdrup—an increase of about 50 to 60%—while the lower part has weakened by around 10 to 20%. However, these changes have not been caused entirely by climate change. Natural climate patterns, including the Interdecadal Pacific Oscillation, have also played a role.
One study suggests that under the worst climate change scenario, the Southern Ocean circulation could lose about half of its strength by 2050. This raises an even bigger concern: the Southern Ocean overturning circulation may not simply continue weakening as the climate warms. Instead, it could eventually collapse completely. Such a collapse would be extremely difficult to reverse and could become an example of a climate tipping point—where a system passes a critical limit and begins changing in a much more dramatic way.
Some early research suggests a collapse could become more likely if global warming reaches between about 1. 7°C and 3°C, though there is much more uncertainty around these estimates than for many other possible climate tipping points. Even if the process begins in the near future, scientists believe a complete collapse of the circulation would probably not happen until close to the year 2300. The effects would not necessarily appear immediately—changes such as less rainfall across parts of the Southern Hemisphere and more rainfall across the Northern Hemisphere could develop over many decades.
The Southern Ocean could also experience major declines in fisheries, with some marine ecosystems potentially collapsing as conditions continue to change. These effects show that changes happening in Antarctica today could eventually influence ocean systems, weather patterns, and marine life far beyond the continent itself.
