A new study led by researchers at the University of Maryland has revealed that Antarctic ice loss may speed up much faster than current climate models predict because of a hidden ocean feedback loop that scientists say has largely been overlooked.
The research, published in the journal Nature Geoscience, found that meltwater flowing from Antarctic ice shelves does more than raise sea levels. It also changes ocean circulation in ways that trigger even more melting, creating what scientists describe as a self-reinforcing cycle.
The study was led by Madeleine Youngs from the university’s Department of Atmospheric and Oceanic Science. According to Youngs, most current global climate models used to guide international policy do not fully include this interaction between melting ice and ocean circulation.
Researchers explained that cold, dense ocean water normally forms a protective barrier near the seafloor, preventing warmer deep ocean water from reaching the underside of Antarctic ice shelves. But when freshwater from melting ice enters the ocean, it weakens that barrier, allowing warmer water to flow underneath the ice and melt it from below.
Scientists say the process creates a dangerous positive feedback loop: more melting leads to more freshwater, which weakens the barrier further and allows even more warm water to reach the ice.
The team found that this effect is particularly severe in regions such as the Weddell Sea, where upstream melting can rapidly intensify ice loss. However, in areas like the Amundsen Sea and near the Thwaites Glacier, often called the “Doomsday Glacier,” the situation is more complex.
There, meltwater moving westward can temporarily form a cold freshwater layer that blocks warmer currents and slows additional melting in the short term. Scientists described this as a negative feedback effect, though they warned that it still depends on massive upstream ice loss already taking place.
The researchers said these findings expose a major blind spot in current projections of future sea level rise. Existing estimates from the Intergovernmental Panel on Climate Change suggest Antarctic ice melt could add up to 28–34 centimeters to global sea levels by 2100 under high emissions scenarios. But the new study indicates the real impact could be significantly larger if ocean feedback loops continue intensifying.
The warning carries major implications for coastal populations worldwide. Scientists noted that more than 680 million people currently live in low lying coastal regions vulnerable to flooding, storm surges, and rising seas, including major cities such as Miami and Mumbai.
Researchers are now developing higher resolution climate simulations to better predict when different Antarctic ice shelves could approach irreversible tipping points. The next phase of the work will focus on identifying which regions are most vulnerable and how quickly the changes could unfold through the end of the century.
Youngs said the study demonstrates that scientists can no longer consider Antarctic melting as a simple response to warming temperatures alone. Instead, the melting itself is actively reshaping the ocean around Antarctica in ways that may further accelerate climate risks globally.