The support line is the transition zone between ice resting on land and ice floating in the sea. Its stability is key to understanding the future of glaciers. A study led by the University of California and published in PNAS reveals that, between 1992 and 2025, Antarctica lost more than 12,800 km of coastline in that transition line, concentrated in 23% of its surface.
The lead author, Eric Rignot, explained that while 77% of the coastline remains stable, the rest has retreated rapidly and drastically, responding to climate change “like a house of cards.”
Most Affected Areas
The most notable retreats were recorded in West Antarctica and vulnerable sectors of the peninsula:
- Amundsen Sea and Getz Ice Shelf: retreats between 10 and 40 km.
- Smith Glacier: 42 km.
- Thwaites Glacier: 26 km.
- Ina Island: 33 km.
In some cases, the ice loss is equivalent to ten times the size of Los Angeles.
Causes of Retreat
The study attributes the changes to the intrusion of warm ocean water under the ice layers, favored by wind alterations caused by climate change.
- Glaciers near sources of warm water were the most affected.
- In the northeast of the Antarctic Peninsula, support line migrations were observed that still have no clear explanation.
Rate of Loss
The ice sheet has retreated from the baseline at an average rate of 442 km² per year. The most impacted areas include:
- Northeast and southwest of the Antarctic Peninsula.
- Wilkes and George V Lands in East Antarctica.
- Sectors of the Bellingshausen Sea and Amundsen Sea.
Satellite Technology and Commercial Data
The team analyzed information from 15 satellite missions, including synthetic aperture radar data from commercial providers.
According to Rignot, the private sector has experienced a “boom” and offers observation capabilities that surpass space agencies, allowing significant scientific advances.
Global Implications
The results will serve as a reference to project the future loss of the Antarctic ice sheet and the consequent rise in sea level. Although much of the coastline remains stable, the affected areas show that climate change can cause rapid and profound transformations in vulnerable regions.
The research confirms that Antarctica, in general, remains stable, but in critical areas, climate change has triggered alarming retreats. These findings reinforce the need to continuously monitor the region and understand how the interaction between oceans and glaciers can accelerate the rise in sea level in the coming decades.
