NASA and a team of glaciologists from the University of California have presented the first continental map documenting how the Antarctic grounding line has changed over the past three decades.
The study, published in Proceedings of the National Academy of Sciences, reveals that although 77% of the coast has remained stable since 1996, certain vulnerable regions are losing ice at a rate equivalent to the area of the city of Los Angeles every three years.
Retreat of Key Glaciers
The data shows that the ice sheet has retreated an average of 442 km² per year. The most significant losses are recorded in West Antarctica, especially in the Amundsen Sea and Getz:
- Pine Island Glacier: retreat of 33 km.
- Thwaites Glacier: retreat of 26 km.
- Smith Glacier: retreat of 42 km.
In the Antarctic Peninsula, glaciers such as Edgeworth (16 km), Boydell, Sjögren, Bombardier, and Dinsmoor also show notable reductions.
Causes of Retreat
Scientists attribute most of the loss to the influx of warm ocean water under the floating ice shelves, which thins the ice from below.
Eric Rignot, principal investigator at NASA’s Jet Propulsion Laboratory, compared it to a balloon: “It’s not punctured everywhere, but where it is, it goes very deep.”
International Satellite Technology
The record was built thanks to the combination of data from multiple satellite missions:
- ERS-1/2 and Sentinel-1 (European Space Agency).
- RADARSAT 1, 2 and RADARSAT Constellation (Canada).
- ALOS/PALSAR-2 (Japan).
- COSMO-SkyMed (Italy).
- TerraSAR-X (Germany).
- SAOCOM (Argentina).
The integration of commercial and space agency observations opened a new era in polar monitoring.
Global Implications
NASA estimates that Antarctica loses 136 billion tons of ice per year, while Greenland loses 267 billion tons. Both contribute directly to the rise in sea level, according to the GRACE and GRACE Follow-On satellites.
Francisco Navarro, from the Polytechnic University of Madrid, warns: “If the grounding line retreats and the area of the shelves decreases, the speed at which the ice sheet expels its ice into the sea as icebergs accelerates.”
A Record for the Future
This study establishes a solid foundation for next-generation models that project sea level rise. If a model fails to reproduce this historical record, it will need to be revised. Continuous Earth observation is essential to refine projections and understand how Antarctica responds to global warming.
The research confirms that Antarctica faces massive and irreversible ice losses in critical areas. Although much of the continent remains stable, the retreat in vulnerable regions is enough to impact sea level and, consequently, the lives of millions of people worldwide. NASA’s warning is clear: there is no turning back.
