NASA JPL-Caltech | 2011 Aug 18
NASA-funded researchers have created the first complete map of the speed and direction of ice flow in Antarctica. The map, which shows glaciers flowing thousands of miles from the continent's deep interior to its coast, will be critical for tracking future sea-level increases from climate change. The team created the map using integrated radar observations from a consortium of international satellites.Click to play embedded YouTube video.
"This is like seeing a map of all the oceans' currents for the first time. It's a game changer for glaciology," said Eric Rignot of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the University of California (UC), Irvine. Rignot is lead author of a paper about the ice flow published online Thursday in Science Express. "We are seeing amazing flows from the heart of the continent that had never been described before."
Rignot and UC Irvine scientists Jeremie Mouginot and Bernd Scheuchl used billions of data points captured by European, Japanese and Canadian satellites to weed out cloud cover, solar glare and land features masking the glaciers. With the aid of NASA technology, the team painstakingly pieced together the shape and velocity of glacial formations, including the previously uncharted East Antarctica, which comprises 77 percent of the continent.
Like viewers of a completed jigsaw puzzle, the scientists were surprised when they stood back and took in the full picture. They discovered a new ridge splitting the 5.4 million-square-mile (14 million-square-kilometer) landmass from east to west.
The team also found unnamed formations moving up to 800 feet (244 meters) annually across immense plains sloping toward the Antarctic Ocean and in a different manner than past models of ice migration.
"The map points out something fundamentally new: that ice moves by slipping along the ground it rests on," said Thomas Wagner, NASA's cryospheric program scientist in Washington. "That's critical knowledge for predicting future sea level rise. It means that if we lose ice at the coasts from the warming ocean, we open the tap to massive amounts of ice in the interior."
The work was conducted in conjunction with the International Polar Year (IPY) (2007-2008). Collaborators worked under the IPY Space Task Group, which included NASA; the European Space Agency (ESA); Canadian Space Agency (CSA); Japan Aerospace Exploration Agency; the Alaska Satellite Facility in Fairbanks; and MacDonald, Dettwiler and Associates of Richmond, British Columbia, Canada. The map builds on partial charts of Antarctic ice flow created by NASA, CSA and ESA using different techniques.
"To our knowledge, this is the first time that a tightly knit collaboration of civilian space agencies has worked together to create such a huge dataset of this type," said Yves Crevier of CSA. "It is a dataset of lasting scientific value in assessing the extent and rate of change in polar regions."
First Map of Antartica’s Moving Ice
NASA Earth Observatory | 2011 Aug 19
Ice moves. It flows in streams and channels. It creeps and compresses and deforms. We see it best perhaps in glaciers birthing icebergs, frozen rivers emptying into the ocean. Now, for the first time ever, we can see just how much ice moves across the entire Antarctic continent, and the view offers up a few big surprises. This new knowledge could help scientists understand how ice is changing now and how it will change as our climate continues to warm in the future. It will help scientists predict how much sea levels will rise as ice melts in coming decades.
This new view of Antarctica in motion comes from thousands of measurements taken by radar instruments on satellites from Canada, Japan, and the European Space Agency between 1996 and 2009. Eric Rignot of NASA’s Jet Propulsion Laboratory and the University of California Irvine led the team of scientists that pieced together the data to figure out how much each section of ice moves per year. An animation of the ice in motion is available from the NASA multimedia gallery.
The end result, shown here, reveals areas where ice moves as quickly as a few kilometers per year (shown in bright purple and red) and other areas where movement is confined to a few centimeters per year (shown in pink). The slowest moving ice is along the divides that separate glacier basins, which are outlined in black. These divides are generally over mountains that shape the flow of ice.
The fastest moving areas are glaciers and ice shelves along the edge of the ice, and of these, the Pine Island and Thwaites glaciers are moving most. The surprise, however, is that channels of fast-flowing ice extend far inland, broad tributaries feeding the glacial rivers.
The ice sheet around the tributaries moves slowly, compressed by its own weight and spreading like a mound of pancake batter. The wide tributaries, shown in blue are not quite as fast as an ice stream, but move faster than the ice sheet around them. This type of moderate-paced motion was a surprise to Rignot and his team.
“We are seeing amazing flows from the heart of the continent that had never been described before,” said Rignot in a NASA release. “This is like seeing a map of all the oceans’ currents for the first time. It’s a game changer for glaciology.”
The finding is a game changer because it adds another type of motion to the ice sheet. Previously, scientists have thought that ice sheets move largely because they are deforming under their own weight, pushing ice to their outer edges. The tributaries, however, are sliding on the ground, implying a relationship between ice motion at the coast and motion along the tributaries inland.
“That’s critical knowledge for predicting future sea level rise,” said Thomas Wagner, NASA’s cryospheric program scientist. “It means that if we lose ice at the coasts from the warming ocean, we open the tap to massive amounts of ice in the interior.”
Ice Flow of the Antarctic Ice Sheet - E. Rignot, J. Mouginot, B. Scheuchl
- Science (online 2011 Aug 18) DOI: 10.1126/science.1208336
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Wired Science | Danielle Venton | 2011 Aug 19
I kind of thought that striations left behind all accross the glaciated areas by the last major Ice Age kind of solved that one for us?