November 8, 2013
Glacier ‘Tiger Stripes’ Slowing Down Ice Flow In Antarctica
Lee Rannals for redOrbit.com – Your Universe Online
Researchers writing online in the journal Science say they have found narrow stripes of dirt and rock underneath Antarctic glaciers create friction zones that slow the flow of ice toward the sea.
These ribs, or “tiger stripes,” provide friction that hinders the glaciers from slipping along the underlying bed of rock and sediment. Understanding how these regions form and subside could help scientists know more about the flow of these glaciers in response to climate change.
The team found the tiger stripes using mathematical modeling based on data from the National Snow and Ice Data Center and the British Antarctic Survey. They hope to find out what factors determine the flow of glaciers, which could contribute substantially to sea level rise if they flow into the ocean.
Researchers studied two glaciers in West Antarctica that together contribute about ten percent of the observed sea-level rise over the past 20 years. They said the Pine Island Glacier moves at a velocity of about 1.5 miles per year.
Studying the bottom of these glaciers is impossible due to the inability to see through the ice, so the team used satellite measurements of the ice velocity and radar data collected from airplane flyovers to detect bedrock and surface topography. After this they created a mathematical model that calculated what happens inside the glacier as it flows along the bedrock.
The tiger stripes sit at about 30-degree angles to the direction of the glacier’s movement, rising and decaying in response to natural processes.
"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," Olga Sergienko, an associate research scientist in Princeton's Program in Atmospheric and Oceanic Sciences, said in a press release. "These changes can happen independently of climate change, too," she added.
The team says more studies are needed in order to verify the models of rib formation. They believe these ribs are related to typical landforms that exist in the formerly glaciated areas of North America and Europe.
Douglas MacAyeal, a professor of glaciology at the University of Chicago, who was not involved in the work, said the study reveals new patterns of friction that help control the speed of ice flow and determine the effect of Antarctic ice on sea level.
"This is strongly suggestive of a new style of physical controls over friction, like water flow in the thin zone between the rock of the bed and the ice," he said in a press release. "The results of this study will drive new theoretical and observational efforts to understand what causes this pattern."