Sea ice loss triggers Antarctic ice shelf collapse

Scientists have identified a clear pattern that links sea ice retreats to large-scale iceberg calving events in Antarctica, revealing how seawater bends and destroys weakened ice shelves when protective barriers disappear.

Researchers tracked three major calving events over seven years and found that sea ice caused prolonged losses in the 6-18 months before the collapse, leaving ice shelves vulnerable to destructive waves, eventually triggering their rupture.

Published in Natural Earth Sciences, these findings provide the first comprehensive model connecting sea ice conditions, ocean expansion and ice shelf stability, which is crucial to predict future collapses as it collapses at an unprecedented rate due to climate change.

Threatened protective barriers

“Sea ice is retreating at an unprecedented rate and our work shows that this will put further pressure on the already sparse and weakened ice shelves,” explained Professor Luke Bennetts of the University of Melbourne. “This could lead to larger calving events that have profound implications for the future of global sea levels.”

The team developed a mathematical model to quantify the massive expansion of elastic ice shelves in the south and then track the conditions that led to calving events that led to Wilkins and Voyeykov ice shelves. Their analysis shows that the three-stage pattern before the collapse is consistent:

• Long-term reduction of ice cubes starts from 6-18 months before calving
• “Fast Ice” was lost in the last few weeks before the collapse (ice is fixed on the shelf)
• The continuous intense ice shelf never hinders the hairon bending

The protection of sea ice has proven to be crucial because it serves as a buffer between ice shelves and potentially destructive ocean waves. “In addition to the relatively short periods near summer, sea ice creates protective barriers between ice shelves and potentially destructive expansion in the Southern Ocean,” Bennett said. “Without such barriers, the expansion can be bent and bent toward the ice shelf until it breaks.”

Mathematical models reveal hidden connections

The researchers found that the sea ice barrier equivalent to 100 kilometers provides protection comparable to the thickness of the other 50-100 meters of ice shelf. This mathematical relationship helps explain why relatively thin ice shelves (100 meters below the thickness of the final flat area) are particularly susceptible to wave-induced bending.

The study tracked the “bending pressure” caused by ocean swelling over the years and found that ice shelves experienced the highest levels of continuous stress over the years before major calving events. The team measured the accumulated pressure over a 60-day period, representing the cumulative fatigue effect of repeated waves affecting already damaged ice.

For Wilkins Ice Shelf, the model predicted stress levels exceeded the long-term extension threshold before the 2008 calving event, which 17% removed 17% of the shelf area. Voyeykov ice shelves showed similar patterns before losing 14% of their area in 2007.

Destruction process

The study revealed that ice shelf collapse is a cascade process, not a sudden event. The initial sea ice retreat was exposed to ice shelves to increase the volatility, creating the pressure accumulated over months. The fast ice is directly connected to the shelf frontline to provide the final protective layer, but when such ice shelves explode (usually a few weeks before large calving), the exposed ice shelves become completely vulnerable to destructive ocean expansion.

The timing of this study captured natural experiments between 2002 and 2009, as atmospheric conditions such as LaNiña mode and continuous low-pressure systems drive regional sea ice loss around the Antarctic Peninsula. These conditions eliminate the protective barrier and have been exposed to the full force of the already broken ice shelf edge to the Southern Ocean.

Current observation systems do not typically monitor waves in Antarctic sea ice regions, making mathematical modeling crucial for understanding these connections. The researchers’ model successfully predicted stress patterns for other recorded calving events, including the collapse of McMurdo 2016 and Conger-Glenzer 2022.

Impact on future sea level rise

While the ice shelf collapse did not directly raise sea levels (as the ice has floated) eliminated the critical obstacles to flowing from land into the ocean. The Antarctic ice sheet contains enough water to increase global sea level by 50 meters, making ice shelf stability crucial for long-term predictions.

Research shows that the ongoing Antarctic sea ice resort will be an increasingly important factor in the collapse of ice shelves in the future. However, the model shows that only relatively thin ice shelves face the vulnerability of immediate susceptibility to wave-induced collapse, thus reassuring the assurance on thicker, more stable ice shelves.

As warm temperatures spread around Antarctica’s coastline, understanding how sea ice loss affects the stability of ice shelves is critical to reducing uncertainty in sea-level projection and preparing for future changes in Antarctic ice dynamics.

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