Antarctica is at the center of a new scientific picture that helps explain why floating sea ice grew for decades and then suddenly fell away in 2016. A new paper tied to deep-diving robots points to salinity, winds, and ocean churn as the main forces behind the shift. The finding matters because the loss of sea ice could affect Antarctica’s vast ice sheet and, if that ice sheet disappeared, sea levels would rise by 190 feet.
What the robots found beneath Antarctica
The study drew on a network of data-gathering machines known as Argo floats, which sink thousands of feet, measure temperature and salinity, then rise and send the information to a satellite. In the waters around Antarctica, those measurements helped scientists see how cold surface water and warmer water below interacted over time. Earle Wilson, a polar oceanographer at Stanford University and lead author of the new paper, said one key takeaway is that the ocean plays a major role in how sea ice varies from year to year and decade to decade.
For years, the pattern around Antarctica looked unusual. From the 1970s until about a decade ago, sea ice had been expanding even as climate change advanced. Then in 2016, the system shifted sharply, and the sea ice has not recovered. The new work links that change to fresher surface waters, stronger layering in the ocean, and a later disruption that allowed deeper heat to rise.
Antarctica and the new low-ice era
The satellite-based study also shows that Antarctica is moving through a dramatic change in sea-ice coverage with consequences for the region’s marine food web. About 10 years ago, an expanse of ocean around Antarctica lost its seasonal ice within just a few years, a step-like drop described as the start of a new low-ice era. That change pushed the Southern Ocean from extremely low phytoplankton levels to more moderate productivity, with chlorophyll-a shifting between the earlier stable sea-ice period and the low-ice era.
This is not just a story about ice at the surface. The altered conditions around Antarctica are being tracked because sea-ice loss can reshape the environment that supports key plankton species, and those species underpin the wider marine food web.
Why the change happened so fast
The new paper points to a sequence of events. As sea ice expanded in the years before 2016, more precipitation made surface waters fresher than the saltier waters below, creating stratification. That layering trapped warmth in the depths. Then intensified and shifting winds pushed surface waters away from Antarctica and stirred up that stored heat. Wilson described the result as a violent release of heat from below that was linked to the sea-ice decline.
Scientists say the wind changes were likely driven at least in part by climate change, because warming can strengthen atmospheric temperature gradients and alter wind patterns. They also note that work is still underway to separate that influence from natural variability.
What comes next for Antarctica
Researchers are now continuing to sort out how much of the shift around Antarctica is tied to human-driven warming and how much may reflect natural variability. The broad picture is already clear: Antarctica has entered a new phase of lower sea ice, and the ocean beneath it appears to be a central reason why. As scientists keep reading the data from deep-diving robots and satellites, Antarctica remains the place where the next answers are likely to emerge.
