'Tiger stripes' under Antarctic glaciers slow their flow to the ocean

Narrow stripes of dirt and rock beneath massive Antarctic glaciers act like no-slip strips on a floor to slow the flow of ice toward the sea, scientists say. Researchers at Princeton University and the British Antarctic Survey said understanding how the high-friction regions form could help increase understanding of how the glaciers' flow responds to a warming climate. The massive, moving ice sheets can contribute substantially to sea-level rise when they flow into the ocean. Dubbed "tiger stripes" after Princeton's tiger mascot, the formations provide friction that hinders the glaciers from slipping along the underlying bed of rock and sediment, the scientists said. Studying the bottom of mile-and-a-half-thick Antarctic glaciers is next to impossible due to the inability to see through the ice, so the researchers used satellite measurements of the ice velocity and ground-penetrating radar collected from airplane flyovers to detect bedrock and surface topography. The tiger stripes, which the researchers also call ribs, due to their slightly curved structure, lie at roughly 30-degree angles to the direction of the glacier's movement, and arise and decay in response to natural processes over roughly 50 to 100 years, the scientists calculated. The process is strongly affected by how water, melted from the ice by inherent heat trapped inside Earth, infiltrates the space between the ice sheet and the bedrock, they said. "The ribs may play an important role in buffering the effects of a warming climate, since they slow the movement of ice that reaches the ocean and contributes to sea-level rise," Princeton researcher Olga Sergienko said. "These changes can happen independently of climate change, too."