Glacial retreat in West Antarctica began in the 1940s

The glaciers Thwaites and Pine Island, two of the most important in the Antarctica Western countries, they would have begun their significant decline as early as the 1940s, thus sharing a common history of weight loss.

A team led by the University of Houston (USA) that publishes the journal PNAS studies the history of the Thwaites glacier, the widest in the world and measuring about 130 kilometers, and its results coincide with previous studies on the retreat of the Pine Island.

The Thwaites loses about 50 billion tons of ice more than it receives in the form of snow, which endangers its stability. An accelerated process that has been observed since the 1970s, but the new study places the beginning of this mechanics in the 1940s.

The results of the new research on the Thwaites Glacier coincide with previous work that studied the retreat of the Pine Island Glacier and found that it began in the same decade.

“A significant implication of our findings is that once an ice sheet retreat is set in motion, it can continue for decades, even if what started it does not worsen,” according to James Smith, from the British Antarctic Survey and co-author of the study.

The team suggests that Thwaites’ first retreat was likely triggered by an extreme El Niño weather pattern that warmed West Antarctica, from which it has not recovered, and currently contributes 4% to global sea level rise.

If the glacier were to completely collapse, it is estimated that global sea level would rise by 65 centimeters.

Is “significant” El Niño may only last a couple of years but Thwaites and Pine Island are still in sharp decline, indicating that “Once the system becomes unbalanced, the regression is continuous,” highlighted fellow signatory Julia Wellner, from the University of Houston.

The most important thing about the study – according to the team leader, Rachel Clark – is that this change “it is neither random nor specific to a glacier,” but is part of “a broader context of climate change. “You cannot ignore what is happening on this glacier.”

The research also establishes that the retreat in the glacial grounding zone, or the area where glaciers lose contact with the seabed and begin to float, was due to external factors.

Thwaites and Pine Island share a common history of thinning and retreat, corroborating the view that ice loss in West Antarctica is predominantly controlled by external factors rather than internal glacier dynamics or local changes, such as melting in the glacier bed or the accumulation of snow on the surface.

The Thwaites Glacier plays a vital role in regulating the stability of the West Antarctic Ice Sheet and therefore global sea level rise, according to Antarctic researchers.

Thwaites is significant not only for his contribution to sea level, but also acts as “a cork in the bottle” which retains a larger area of ​​ice behind him”: if it destabilizes, “there is a possibility that all the ice in West Antarctica will destabilize”Wellner warned.

This study helps “to better understand which factors are most critical in driving the thinning and retreat of the glaciers that drain the West Antarctic Ice Sheet into the Amundsen Sea”said Claus-Dieter Hillenbrand, also a signatory of the study.

These results will improve, according to the scientist, numerical models that attempt to predict the magnitude and pace of future melting of the Antarctic ice sheet and its contributions to sea level.