Researchers from UC San Diego’s Scripps Institution of Oceanography have collaborated with the University of Cambridge in a groundbreaking study revealing significant changes in the Southern Ocean. This research indicates that a warm water mass known as “circumpolar deep water” has expanded and migrated towards the Antarctic continental shelf over the last two decades.
Scripps physical oceanographer Sarah Purkey noted the alarming implications of this shift, explaining, “In the past, the ice sheets were protected by a bath of cold water, preventing them from melting. Now it looks like the ocean’s circulation has changed, and it’s almost like someone turned on the hot tap and now the bath is getting warmer.” Ice shelves are critical in supporting Antarctica’s glaciers and inland ice sheets, which collectively could elevate sea levels by approximately 58 meters (190 feet) if fully melted.
Joshua Lanham, the lead author of the study at Cambridge Earth Sciences, emphasized the gravity of the situation: “It’s concerning because this warm water can flow beneath Antarctic ice shelves, melting them from below and destabilizing them.” This study marks the first documented observation of deep-ocean heat changes throughout the Southern Ocean, a scenario previously predicted by climate models due to global warming but not confirmed through data until now.
In the past, information about the Southern Ocean, which encircles Antarctica, was largely limited to sporadic ship-based observations about once a decade. Researchers traditionally relied on these snapshots to understand temperature, salinity, and nutrient levels, but the lack of continuous data left significant gaps in their understanding of long-term heat distribution. To address this, the researchers combined ship data with insights from a global array of robotic floating instruments known as Argo, resulting in monthly snapshots that clearly illustrate the shift in warm waters.
Purkey underscored that this increase in warmer water is expected, as over 90% of excess heat from global warming is sequestered in the ocean, with the Southern Ocean absorbing a substantial portion of this heat.
The implications of these findings extend beyond Antarctic ice melt and rising sea levels. Ali Mashayek, another senior author from Cambridge Earth Sciences, pointed out that the Southern Ocean plays a pivotal role in global heat and carbon regulation. Changes in heat distribution here could have broader impacts on the global climate system. In polar regions, extremely cold water forms and sinks, creating a global “conveyor belt” of currents, including the Atlantic Meridional Overturning Circulation (AMOC), which influences oceanic water movement.
Climate models, notably those from the Intergovernmental Panel on Climate Change (IPCC), suggest that increased air temperatures and additional freshwater from melting ice are diminishing the formation of this dense water in the North Atlantic, potentially weakening the AMOC. Similar forecasts are emerging for the Southern Ocean, predicting a decline in cold, dense water production, allowing warmer circumpolar deep water to encroach upon the continent.
“This isn’t just a possible future scenario suggested by models; it’s something that is happening now,” Lanham concluded, pointing to significant consequences for the cycling of carbon, nutrients, and heat throughout the global ocean.
The study adds to the growing body of evidence highlighting the urgent need for climate action, as changes in oceanic conditions could have far-reaching effects on climate patterns worldwide. Additional researchers involved in the study include Matthew Mazloff from Scripps Oceanography, Kaushik Srinivasan from UCLA, and Laura Cimoli from Cambridge. The findings were published in the journal Nature Communications Earth & Environment.
Original Source: https://oceannews.com/news/science-technology/long-term-study-reveals-deep-ocean-heat-has-been-marching-closer-to-antarctica/
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Publish Date: 2026-04-28 20:57:00
