"Warm circumpolar deep water has expanded and shifted closer to the ice, threatening to melt ice shelves from below."
A new study combining ship-based data and Argo float measurements reveals that warm circumpolar deep water (CDW) is moving toward the Antarctic continental shelf, threatening to melt ice shelves from below.
The research, conducted by scientists at the University of Cambridge and the University of California, provides a 40-year monthly record of ocean conditions. It shows that CDW has both expanded and shifted closer to the ice, marking a significant long-term change in Southern Ocean dynamics.
Professor Sarah Purkey of Scripps Institution of Oceanography described the change as analogous to turning on a hot tap. The study indicates that warming CDW not only melts ice shelves but also pushes back the grounding line—the boundary where ice meets bedrock—accelerating ice loss.
The cause of this ocean warming remains uncertain, possibly combining natural variability and human-induced climate change.
Broader Climate Implications
The Southern Ocean plays a key role in regulating global heat and carbon storage. Changes in heat distribution there have direct implications for the global climate system. A slowdown of the Atlantic Meridional Overturning Circulation (AMOC) could result, with potential impacts on sea levels and weather patterns worldwide.