The "Heater" Beneath the Glaciers Turns On... Antarctica's "Hidden Variable" Advances 1km Toward the Continent Each Year [Reading Science]

Circumpolar Deep Water Has Shifted 1.26 km per Year Over Two Decades
“Signal of Accelerated Basal Melting Beneath Antarctic Ice Shelves”

An analysis of decades of accumulated ocean observation data has revealed that deep-sea heat surrounding Antarctica is rapidly moving toward the continent. This suggests that the “hidden heat supply” melting the ice shelves from below is intensifying, making it a key variable that could accelerate sea level rise.

A joint research team from the University of Cambridge in the UK and the University of California in the US combined ship-based and ocean float observation data to analyze the deep structure of the Southern Ocean. They found that the relatively warm Circumpolar Deep Water (CDW), which surrounds Antarctica, has been moving toward the Antarctic continental shelf over the past 20 years. The results of this study were published on April 28 (Korean time) in the international journal Communications Earth & Environment.

View of the Bellingshausen Sea, Antarctica, taken aboard the research vessel R/V Falkor in 2025. Photo by Laura Cimoli, University of Cambridge

The researchers reconstructed monthly ocean data over the past 40 years by merging existing ship-based observation records and data from globally distributed floating instruments (Argo) using machine learning. This analysis confirmed that the thickness of the warm water layer in the upper approximately 2,000 meters near Antarctica has increased.

Notably, the core of the CDW has shifted toward the Antarctic continent at a rate of about 1.26 kilometers per year. At the same time, the heat content within this water layer has also increased, indicating that the supply of heat delivered to the underside of Antarctic ice shelves is expanding.

"Melting from Below the Ice Shelves"... A Key Variable in Sea Level Rise

The CDW is considered the main heat source melting the base of Antarctic ice shelves from below. As this water penetrates deeper onto the continental shelf, basal melting of the ice shelves accelerates, which can lead to glacier collapse and further sea level rise.

Won Sang Lee, principal researcher at the Korea Polar Research Institute, told the Korea Science and Technology Media Center, "This study is significant because it quantitatively analyzed the movement and heat distribution of deep water by combining Antarctic observation data, which had long gaps, through machine learning." He added, "The results themselves will serve as a critical input for predicting basal melt rates of ice shelves and projecting sea level rise."

Seong Hyun Nam, a professor at Seoul National University, also commented, "The influx of CDW onto the continental shelf is a key cause of West Antarctic ice shelf melting, and this research offers important implications for sea level rise projections."

Reference photo to assist in understanding the article. Melting Antarctic ice. Photo by EPA / Yonhap News Agency

However, the researchers explained that this study focuses more on changes in the distribution and thickness of warm water rather than on “temperature rise” itself, and that further research is needed to determine which factors most significantly contribute to the actual increase in heat supply.

Observation Gaps Remain... "Urgent Need for Long-term Polar Observation Networks"

Due to the difficulty of access, the Southern Ocean has the limitation of restricted long-term, continuous observations. Even now, observation networks south of latitude 65 degrees, at depths below 2,000 meters, and beneath the ice shelves remain “blind spots.”

Consequently, securing next-generation observation technologies—such as Polar Argo floats that can avoid sea ice, Deep Argo that can measure down to 6,000 meters, and autonomous underwater vehicles (AUVs)—is considered a major task.

Experts stress that these changes are not merely polar phenomena but global warning signals, as the collapse of Antarctic ice shelves and resulting sea level rise could directly impact coastal regions worldwide.

Principal researcher Lee said, "The ocean is a massive reservoir that has absorbed about 90% of the heat emitted by humanity," and added, "Given that today’s decisions to reduce greenhouse gases will determine sea levels centuries from now, this study holds major policy implications as well."

This content was produced with the assistance of AI translation services.