Breakthroughs in Mapping Ice Sheet Flow: How New Radar Tech Reveals Hidden Glacier Secrets

The retreat of glaciers and ice sheets threatens communities globally by driving sea level rise. Over the past three decades, the global average sea level has climbed more than 10 centimeters, with the rate of increase accelerating. This trend intensifies storm surges, flooding, and the loss of infrastructure and land. Recent studies highlighting the instability of Antarctica’s Thwaites Glacier underscore how rapidly shifting ice flow can trigger ice sheet collapse and catastrophic sea level rise.

Yet predicting the pace of ice loss from Thwaites and other glaciers remains uncertain. A key challenge is our incomplete understanding of the complex processes governing ice sheet mass balance. Ice sheets grow through snowfall but lose mass via surface melting, iceberg calving, and ocean-driven melting at their base. The flow of glacial ice under its own weight toward coastal regions is a primary driver of mass loss. This flow rate depends on two critical factors: the resistance at the ice-bed interface (e.g., whether the ice is frozen to the ground) and the ice’s effective viscosity—a measure of its resistance to deformation.

The viscosity of ice varies with temperature, crystal size and orientation, and impurity content. Some properties within and beneath ice sheets are anisotropic, meaning they change depending on direction. For example, the roughness of the bedrock in certain directions can enhance ice sliding, much like a corrugated metal roof allows snow to slide off more easily. Anisotropy also arises from the alignment of ice crystals, known as ice fabric, which influences how ice deforms and flows (Figure 1).

Measuring these anisotropic properties is essential for improving projections of how changes at the edges of the Greenland and Antarctic ice sheets will contribute to sea level rise. Recent advancements in ice-penetrating radar technology and data processing are transforming our ability to observe directionally varying ice sheet properties. These innovations enable scientists to account for previously overlooked processes in ice flow models, offering more accurate predictions of future mass changes.

Ice Fabric: The Hidden Architect of Glacier Flow

Ice fabric—the orientation of crystals within the ice—is the most studied and arguably most influential anisotropic property. As ice deforms, such as when it stretches horizontally during its flow toward the coast, its millimeter-scale crystals reorient. This reorientation creates a memory of past deformation, which in turn modulates how the ice will flow in the future. Understanding ice fabric is therefore critical for predicting the behavior of glaciers like Thwaites, where rapid changes could have global consequences.

Radar Technology: Illuminating the Hidden Layers of Ice Sheets

Modern ice-penetrating radar systems emit pulses that penetrate deep into the ice, revealing its internal structure. By analyzing how these pulses reflect off layers of ice with different properties, scientists can map anisotropic features such as crystal alignment and bedrock roughness. Recent improvements in radar resolution and data processing have unlocked new insights into the complex dynamics of ice sheets. These technologies are paving the way for more precise models of ice flow and mass loss, helping researchers address one of the most pressing challenges of climate change.