CU Boulder Team Uncovers Rapid Retreat of Hektoria Glacier

A research team at the University of Colorado Boulder has identified a rapid retreat mechanism affecting the Hektoria Glacier in Antarctica, which lost nearly half its mass in just two months. This unprecedented retreat, documented between January 2022 and March 2023, marks the fastest recorded retreat of a grounded glacier, retreating approximately 15.5 miles during this period.

The glacier, which measures about 8 miles across and 20 miles long, captured the attention of Naomi Ochwat, a research affiliate at CU Boulder. After observing the glacier’s rapid withdrawal, she sought to understand the underlying processes. “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,” Ochwat explained. The implications for sea level rise could be serious, given that fast ice previously supported Hektoria’s ice tongue, a floating extension of the glacier.

As warmer conditions led to the breakup of this fast ice, the glacier’s floating ice tongue began to disintegrate into the ocean. Ted Scambos, a senior research scientist at CU Boulder, noted that while the immediate impact on sea levels is minimal, the revelation of this retreat mechanism raises critical questions about the stability of other glaciers in Antarctica.

Understanding the Retreat Mechanism

Scientists discovered that the glacier’s rapid retreat was primarily due to a calving process occurring on an ice plain — a flat area of bedrock below sea level. As water thinned the glacier, the ice resting on the bedrock began to rise. This led to increased pressure underneath, resulting in large ice slabs breaking off, a phenomenon described by Scambos as similar to “dominoes falling over backwards.”

Ochwat emphasized the significance of understanding this mechanism, stating, “The important thing is this ice plain that thins and starts to float and causes a rapid retreat. That process hasn’t been seen before.” The research team used satellite-derived data, including images and elevation measurements, to analyze the glacier’s behavior.

This study suggests that glaciers resting on ice plains may be particularly vulnerable to destabilization. Historical data indicate that during previous periods, such as 15,000 to 19,000 years ago, Antarctic glaciers with ice plains retreated at alarming rates, sometimes hundreds of meters per day. This context helps researchers interpret the rapid retreat of the Hektoria Glacier.

Implications for Sea Level Rise

The retreat of the Hektoria Glacier, while significant in its rapidity, contributes only fractions of a millimeter to global sea levels. However, the broader implications of this research resonate deeply. Ice sheets contain vast amounts of water, and their melting can lead to substantial increases in sea level. According to the National Oceanic and Atmospheric Administration, nearly 30% of the U.S. population resides in coastal areas vulnerable to flooding, shoreline erosion, and storm hazards exacerbated by sea level rise. Globally, eight of the ten largest cities are located near coastlines, as highlighted by the U.N. Atlas of the Oceans.

“What happens in Antarctica does not stay in Antarctica,” Ochwat stated, emphasizing the importance of ongoing research into these processes. As scientists continue to study the dynamics of glacial retreat and its potential consequences, understanding the Hektoria Glacier’s rapid withdrawal becomes a vital piece of the puzzle in addressing global climate challenges. The findings underscore the need for vigilance in monitoring other potentially unstable regions in Antarctica, as the effects of climate change continue to unfold.