Measuring how – and where – Antarctic ice is cracking with new data tool

UNIVERSITY PARK, Pa. — A total collapse of the roughly 80-mile-wide Thwaites Glacier, the widest in the world, would trigger changes that could lead to 11 feet of sea-level rise, according to scientists who study Antarctica. To better predict fractures that could lead to such a collapse — and to better understand the processes driving changes in Antarctic ice shelves — a team led by researchers at Penn State developed a new method to evaluate cracks that destabilize ice shelves and accelerate those losses.

They reported their technique for analyzing fractures in the ice shelves, which are floating tongues of ice connected to land that extend out to float on ocean water, in the Journal of Geophysical Research: Earth Surface.

Drawing from NASA satellite data, the researchers focused on measuring vertical fractures in the Antarctic ice sheet — which shrinks by around 136 billion tons every year but is still the largest on Earth — over time. The group specifically evaluated ice fractures in the Thwaites Glacier, the so-called “Doomsday Glacier” in West Antarctica, to develop their method, which could help reveal the structural integrity of ice shelves and if – and when – they might give way, the researchers said.

“We know little about fractures, and their behavior is much more complex than conventional models suggest,” said lead author Shujie Wang, assistant professor of geography and faculty associate in the Earth and Environmental Systems Institute at Penn State. “Conventional models depend largely on simplified models and scarce, hard-to-obtain field observations.”

Modeling ice-shelf retreat is complex, especially due to limited data on ice fracturing. This challenge is pronounced at the Thwaites Ice Shelf, an extension of the Thwaites Glacier that is known for its rapid changes, fractured surface and fast ice flow, according to the researchers. They said they see the Thwaites shelf as a bulwark against further disintegration of the glacier.

Richard Alley, Evan Pugh University Professor of Geosciences at Penn State and a co-author on the paper, likened ice shelves to flying buttresses, an architectural feature that holds up exterior building walls.

“We’ve seen ice shelves break off, but we’ve never seen one grow back,” Alley said. “This new research indicates we can predict better the point at which these will break off. It’s helping to establish the early-warning signals.”

To establish more detail about fracture depth and activity, the research team analyzed data collected by NASA’s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) from 2018 to 2024. The satellite measures glaciers, ocean heights, tree canopies and other natural features.

The researchers developed a workflow for processing and analyzing the satellite data to measure fractures over time. The two-step approach generates high-resolution profiles of surface elevations and visual cross-sections of the fractures. Building on an earlier algorithm that Wang developed to detect individual fractures, the new method reveals a range of fracture types and characteristics amid shifting landscapes.

Among their discoveries, the researchers found more aggressive fracturing in the Thwaites shelf’s eastern part and relative stability to the west. Although they did not determine certain causes for the differences, they said warmer winter air, reduced sea ice and changes in the ocean circulation beneath the ice shelf are potential contributors to fracture growth that require more research.

Worsening fractures promote faster ice flow and a domino effect of fissures and instability within ice formations, according to the researchers. Wang said their study should contribute to overall understanding of fracture origins.

“We believe that if the Thwaites Glacier gets very unstable, it will have catastrophic consequences,” Wang said. “It’s an important area to be studied, to say what’s going to change next.”

The work follows a 2023 research paper, also led by Wang, that explored the 2002 collapse of the Larsen B Ice Shelf on the Antarctic Peninsula. Atmospheric and oceanic factors weakened the shelf over a period of years, leading the 1,250-square-mile body to break up and fall apart over about five weeks, that research found.

While conventional modeling of ice-shelf fractures has depended on theory, the new observations provide a foundation for more refined models that should emerge from longer-term research, Wang said.

Part of her hope, she said, is that better predictions on the behavior of Antarctic ice will lessen uncertainty around sea-level changes, contribute to public confidence in scientific research and help inform policymaking.

“I feel this is a bridge, really,” Wang said.

For future research efforts, Zhengrui Huang, doctoral candidate in geography and co-author on the paper, assembled satellite data for more than 40 Antarctic ice shelves. The dataset involves 3D fracture features, with details featuring locations and depths.

The group intends to offer that material as an open-source resource for use by the wider research community, Huang said.

“We expect this will be a key observational dataset of fractures for researchers who study and model Antarctic ice-shelf dynamics,” he said.

Other contributors to the paper from Penn State include Sridhar Anandakrishnan, professor of geosciences and faculty affiliate at the Earth and Environmental Systems Institute; Byron Parizek, professor of mathematics and geosciences and environmental scholar at the institute; and Amanda Willet, doctoral candidate in geosciences.

Patrick M. Alexander, associate research scientist at Lamont-Doherty Earth Observatory at Columbia University, also contributed.

The research was supported by the NASA Cryospheric Sciences Program, the U.S. National Science Foundation, the Heising-Simons Foundation and the Penn State College of Earth and Mineral Sciences John T. Ryan, Jr., Faculty Fellowship.

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