A team from the University of Colorado Boulder has identified a previously unobserved process that led to the rapid retreat of the Hektoria Glacier in Antarctica, which lost approximately half its mass in just two months. Research indicates that this glacier retreated faster than any other grounded glacier on record, moving about 15.5 miles between January 2022 and March 2023.
The rapid changes observed in the Hektoria Glacier came to light through the efforts of Naomi Ochwat, a research affiliate at CU Boulder. Monitoring the glacier, she noted its unprecedented speed of retreat, prompting her to investigate the underlying causes. Ochwat emphasized the potential implications of this phenomenon, stating, “This process, if it could occur on a much larger glacier, then it could have significant consequences for how fast the ice sheet can change as a whole, and other kinds of destabilizing mechanisms could ensue.”
The Hektoria Glacier, which measures approximately 8 miles across and 20 miles long, has a minor impact on sea level rise, contributing only fractions of a millimeter. Yet, its significance lies in the insight it provides into glacial dynamics. Senior Research Scientist Ted Scambos explained that understanding the mechanisms of this retreat could reveal other areas in Antarctica that may experience similar rapid changes.
Central to the glacier’s retreat was the role of fast ice, a layer that typically supports the glacier’s ice tongue, which extends into the ocean. As warming conditions persisted, this layer fractured, leading to the disintegration of the floating ice tongue. Scambos noted, “What was unprecedented was what happened to the Hektoria Glacier as it rested on top of its ice plain, which is a flat area of bedrock below sea level.”
As warmer water thinned the glacier, it caused the ice resting on the bedrock to rise, resulting in pressure that led to significant calving events. Scambos likened this chain reaction to “dominoes falling over backwards,” where the failure of one slab of ice triggered a series of subsequent collapses.
Ochwat highlighted the importance of these findings within a broader context. “The fact that Hektoria retreated and dumped a bunch of ice into the ocean doesn’t really change much, to be completely honest. The important takeaway is this mechanism that hasn’t been seen before.”
The research team utilized satellite-derived data, including images and elevation measurements, to analyze the glacier’s changes. Their findings suggest that glaciers resting on ice plains, like Hektoria, can be particularly vulnerable to destabilization. Previous research indicated that during the last glacial period, Antarctic glaciers with similar characteristics retreated significantly, which provides valuable context for understanding the current dynamics.
According to Scambos, the Hektoria Glacier’s retreat is the fastest observed for any grounded glacier, marking a pivotal moment in glaciology. “It meant this grounded glacier lost ice faster than any glacier had in the past,” he said. Recognizing this trend is crucial for identifying other vulnerable areas in Antarctica that may also undergo rapid retreat.
The implications of such changes extend beyond Antarctica. Ice sheets store vast amounts of water, and their melting poses serious risks for global sea levels. According to the National Oceanic and Atmospheric Administration, nearly 30% of the United States population resides in coastal areas where rising sea levels contribute to flooding and erosion risks. Globally, eight of the ten largest cities are situated near coastlines, underscoring the far-reaching consequences of Antarctic glacial changes.
Ochwat concluded with a warning about the interconnectedness of climate systems: “What happens in Antarctica does not stay in Antarctica, and that’s why it’s really important to research these things because there’s so much we don’t know and so much that could have profound effects for us.” The findings from this research pave the way for future studies aimed at understanding and mitigating the impacts of climate change on global sea levels.
