The recent rapid retreat of an Antarctic glacier could be unprecedented, a new study suggests, a finding which could have major implications for future sea-level rise.
The researchers found that Hektoria Glacier retreated by more than 8km (5 miles) in just two months in late 2022. The authors believe it could be the first modern example of a process where the front of a glacier resting on the seabed rapidly destabilises. However, there are dissenting views that argue this part of the glacier was floating in the ocean, making the changes impressive but not as unusual.
That Hektoria has undergone huge change is not contested. Its front retreated by about 25km (16 miles) between January 2022 and March 2023, as satellite data shows. Unraveling the causes resembles a 'whodunnit' mystery, notes Naomi Ochwat, the study's lead author.
The case began in 2002 with the collapse of the Larsen B ice shelf in the eastern Antarctic Peninsula, which significantly impacted Hektoria Glacier by allowing it to move and thin faster. By early 2022, the stability provided by the sea-ice that had filled the bay left by Larsen B was disrupted.
In just two months in late 2022, researchers suggest the glacier's front, now classified as 'grounded' on the seabed, retreated at a speed ten times faster than any previously recorded grounded glacier. The authors attribute the rapid retreat to upward forces from ocean water lifting the thinning ice.
This remarkable shift highlights the potential for similar rapid changes in other lightly grounded glaciers in Antarctica, with serious implications for global sea-level rise.
However, the study's findings have not gone without skepticism. Many scientists question the precise location of the grounding line, which determines whether the glacier was indeed grounded or floating, underlining the debate within the glaciological community. This uncertainty complicates the assessment of whether the retreat seen at Hektoria is truly unprecedented or part of a more common ice behavior pattern.
Ultimately, the ongoing changes in the Antarctic ice sheets serve as a reminder of the urgent need to understand the dynamics of these fragile environments as climate change accelerates their transformation.
