Antarctica's Lambert Glacier
The Largest Glacier in the World
Nov 15, 2009 Alexandra Matiella Novak
Ice covers 98 percent of Antarctica in the form of ice sheets and moving glaciers. Glaciers travel towards the coasts of Antarctica where they enter the ocean, hanging onto the bedrock as ice shelves and eventually breaking off to fall into the sea where they float away as icebergs and sea ice. These glaciers hold a majority of the Earth’s fresh water and studying them is a major theme of current climate change research because as they melt, the sea-level rises. Research on how glaciers move from the interior of Antarctica towards the ocean is becoming increasingly important.
Lambert Glacier
The Lambert Glacier is the largest glacier in Antarctica and in the world. It is located in East Antarctica and is about 60 miles wide, over 250 miles long, and about 1.5 miles deep. Ice that feeds the glacier originates in the Antarctic Plateau ice sheet and flows north towards the Amery Ice Shelf. The Amery Ice Shelf hangs out over Prydz Bay and icebergs and sea ice in this bay are most likely chunks of the Amery Ice Shelf breaking off. Along with ice, the Lambert Glacier also transports sediment from the interior of the Antarctic Plateau to Prydz Bay.
Studying Glacier Movement
The Lambert Glacier drains about 12 percent of the total East Antarctic ice volume, making it very sensitive to changes in East Antarctic ice mass balance. For this reason, Lambert Glacier is one of the most closely watched glaciers in Antarctica, and in the world. One aspect of Lambert Glacier that is monitored very closely is the rate at which the glacier moves towards the Amery Ice Shelf.
A scientific study called the Antarctic Mapping Mission used radar signals originating from satellites to measure the velocity of the glacier. During a period from early September to early November 2000, scientists on this mission obtained pairs of radar generated images of the Lambert glacier 24 days apart using the Canadian Space Agency’s RADARSAT-1 satellite. These images can detect characteristics of the glacier such as topography and other surface features. Scientists used a technique called radar interferometry, in which the pairs of images are aligned, to look for areas where these surface features had moved. Knowing the scale of the images, the scientists were able to calculate how far the surface features had moved over a 24-day period.
Glacier Velocity
During the 2000 Antarctic Mapping Mission, scientists found that most of Lambert Glacier had velocities between 400-800 meters (1,210-2,620 feet) per year. However, the portion of the glacier that spreads out over the Amery Ice Shelf had a much faster velocity at 1,000-1,200 meters (3,280-3,937 feet) per year. This means that the glacier is moving faster as it nears and enters Prydz Bay, causing the upper portions to thin.
It is not yet completely understood if Lambert Glacier is losing ice as quickly as its West Antarctica counterparts (e.g. Pine Island Glacier and Kohler Glacier) or on the Antarctic Peninsula. Further monitoring of this glacier and other East Antarctica glaciers will help scientists to determine how much global warming is affecting the mass balance of the Antarctic ice sheet and subsequent sea-level rise.
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Antarctica's Mount Erebus Volcano
Spaceborne Lasers Detect Thinning Ice Sheets
Sources:
NASA Earth Observatory: Lambert Glacier Velocity Map
Rignot, Eric, "Changes in ice dynamics and mass balance of the Antarctic ice sheet", Phil. Trans. R. Soc. A 15 July 2006 vol. 364 no. 1844 1637-1655.
Lambert Glacier Captured by Landsat 7 Satellite
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Lambert Glacier Velocity Image
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