New Scientific Review Identifies Antarctic Coastal Blind Spots Limiting Sea Level Projections

The paper, recently published in American Geophysical Union (AGU)’s Reviews of Geophysics, synthesizes current understanding of how ice, ocean, atmosphere, and the solid Earth interact in Antarctica’s coastal zone, and highlights key knowledge gaps and the need for improved observations at a pan-Antarctic scale.

The paper brings together existing observations, models, and theory to highlight how incomplete data continue to limit estimates of Antarctic ice loss and future sea-level rise.

“Antarctica’s coastal zone is where ocean, ice, atmosphere, and the underlying bed interact—making it central to predicting future sea level rise. Yet limited observations in this region leave critical gaps in understanding, meaning Antarctica remains a major source of uncertainty”, says first author and the chair of the RINGS Action Group, Dr. Kenichi Matsuoka at Norwegian Polar Institute.

The working place inside the plane. Photo: Kenichi Matsuoka / Norwegian Polar Institute

A critical control point for sea level rise

The Antarctic coastal zone is not simply the edge of the continent. It is a tightly coupled system where grounded ice meets the ocean, and where small changes can have outsized consequences. Processes occurring near the grounding zone—the point where ice lifts off the bed and begins to float—can regulate ice discharge or, under certain conditions, trigger feedbacks that accelerate ice loss.

Kenichi Matsuoka is a senior researcher and first author of the publication. Photo: Siri Uldal / Norwegian Polar Institute

Observations over recent decades show that Antarctic mass loss has increased. The most rapid changes are driven by interactions between the ice and surrounding ocean, and by ice flow at the margins of the ice sheet, rather than surface melting alone. Yet key coastal conditions remain poorly mapped.

The biggest gaps—and why they matter

The review identifies persistent gaps in direct observations of coastal bed topography and sub–ice shelf cavities. Because ice sheet models are highly sensitive to conditions at the coast, even advanced models can produce misleading results when this data is missing or poorly constrained.

While satellite observations provide powerful measurements of ice motion and surface change, they cannot observe the bedrock under ice from space.

“Satellite data alone cannot reliably estimate ice loss into the ocean, and computer models alone cannot predict future change. Both depend on accurate knowledge of bed topography. Observations like those proposed in this paper provide a key missing piece”, Matsuoka says.

A modernized plane from the 1940s is what the researchers use for flying. Photo: Kenichi Matsuoka / Norwegian Polar Institute

A roadmap for coordinated action

Because no single nation can achieve comprehensive coverage alone, the authors emphasize that international coordination is essential.

“Uncoordinated surveys risk leaving gaps or duplicating effort. This paper provides an evidence-based framework to support coordinating RINGS activities under SCAR and COMNAP, helping to build more comprehensive datasets for improved sea-level projections”, Matsuoka says.

“Such internationally coordinated efforts can serve as a steppingstone towards the next International Polar Year 2032–33”, Matsuoka concludes.

Contributing countries and institutions: