Glaciers surge after ice shelf collapses. (Slippin' Slide).Five of the six large glaciers This is a list of glaciers. Due to somewhat sparse information, some glaciers, especially those in the tropics, may no longer exist as listed. This is especially true for glaciers in Africa and New Guinea. that once fed into Antarctica's Larsen A ice shelf have sped up significantly since that floating ice mass collapsed and drifted away in January 1995, scientists report. Analyses of satellite images and aerial surveys aerial surveys an epidemiological technique for surveying animal populations and their habitat, especially the latter, over a very wide area. Requires special techniques adapted to sensing of electronically marked animals from a distance, and infrared scanning of vegetation. reveal the glaciers' acceleration, says glaciologist Hernan De Angelis of the Argentine Antarctic Institute in Buenos Aires Buenos Aires (bwā`nəs ī`rēz, âr`ēz, Span. bwā`nōs ī`rās), city and federal district (1991 pop. . For instance, photos from orbit show that between February 2000 and September 2001, portions of the Sjogren Glacier glacier, moving mass of ice that survives year to year, formed by the compacting of snow into névé and then into granular ice and set in motion outward and downward by the force of gravity and the stress of its accumulated mass. moved at an average speed of about 2 meters per day. That's about double the speed measured in 1999 and four times the rate clocked in 1995 just after Larsen A's disintegration. De Angelis and his institute colleague Pedro Skvarca report their analyses in the March 7 Science. Although most of the areas large glaciers now flow seaward more quickly, ice upstream at higher elevations has sped up only modestly, if at all. These flow-rate differences affect the glaciers' surface topography. Among the most telling features is a series of 20-to-40-m-tall ice terraces, says De Angelis. Those icy cliffs, first observed in aerial surveys about a year ago, formed as the ice in the glaciers' channels surged seaward and thinned while peripheral ice lagged behind. Although the breakup breakup The division of a company into separate parts. The most famous breakup to date was the 1984 division of AT&T (formerly, American Telephone & Telegraph Company). This breakup was intended to increase competition in the communications industry. of an already floating ice shelf doesn't affect global sea levels, any subsequent flux of new ice from land-based glaciers into the ocean could lead to sea level rises. Because scientists haven't measured the thickness of glaciers that are now freely spilling across the 100-kilometer coastline once fringed by Larsen A, they don't yet know how much global sea levels might be affected, says Skvarca. Scientists have long debated whether ice shelves retard the flow of the glaciers that feed them. De Angelis and Skvarca's new finding strongly suggests that the presence of an ice shelf can matter, says Eric J. Rignot of NASA's Jet Propulsion Laboratory “JPL” redirects here. For other uses, see JPL (disambiguation). Jet Propulsion Laboratory (JPL) is a NASA research center located in the cities of Pasadena and La Cañada Flintridge, near Los Angeles, California, USA. in Pasadena, Calif. A glacier's flow rate can also be influenced by climate and other local conditions, Rignot adds. De Angelis and Skvarca agree that many factors contribute to a glacier's flow rate, including the firmness of rocks or sediments that the ice glides across and the presence of subglacial sub·gla·cial adj. Formed or deposited beneath a glacier. sub  gla melt water.
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