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Home , Amery Ice Shelf, Caird Coast

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Coastal-Change and Glaciological Maps of

Changes in the area and volume of the for the U.S. Geological Survey (USGS), in The coastal-change and glaciological two polar ice sheets in Antarctica (fig. 1) cooperation with Scott Polar Research mapping task, an element of the Glacier and Greenland are intricately linked to Institute (Cambridge, U.K.), to carry out a Studies Project, has five objectives: changes in global climate and could result comprehensive analysis of the glaciological To determine coastline changes in in sea-level changes that would severely features of the coastal regions of Antarctica. Antarctica that have occurred between affect the densely populated coastal regions The project was later modified to include the mid-1970's and the late 1980's/early analysis of coastal change using Landsat 4 on Earth. Melting of the 1990's (Landsat 1-5 MSS and Landsat and 5 MSS and Thematic Mapper (TM) part of the Antarctic ice sheet alone could 4 and 5 TM) and between 1963 and images from the late 1980's/early 1990's, cause a worldwide sea-level rise of approxi­ 1995 where the data are available. mately 6 m. The potential sea-level rise declassified 1963 Argon (Corona Program) after melting of the entire Antarctic ice images, and 1992 and 1995 European Space To establish an accurate baseline series sheet is estimated to be 73 m. In spite of its Agency (ESA) Remote-Sensing Satellite of l:l,000,000-scale maps (fig. 2) that importance, the mass balance (the net volu­ (ERS) radar images. The different data sets defines, from the analysis of remotely metric gain or loss) of the Antarctic ice allow determination of coastal change in sensed data, the glaciological character­ sheet is poorly known; it is not known Antarctica over 15-20 years for the MSS istics (for example, floating ice, whether the ice sheet is growing or shrink­ and TM images and over as much as 32 grounded ice) of the coastline of ing. As a result, measurement of changes in years where Argon and ERS images exist, Antarctica and the location of floating the Antarctic ice sheet has been given a such as the . Coastal ice fronts during the time periods repre­ very high priority in recommendations by change has been most pronounced in the sented by the imagery. Antarctic Peninsula in the last few decades, the Polar Research Board of the National To determine velocities of outlet glaci­ where the Wordie Ice Shelf has practically Research Council, by the Scientific ers, ice streams, and ice shelves from disappeared, the northern part of the Larsen Committee on Antarctic Research (SCAR), comparison of Landsat images of the Ice Shelf has disintegrated, and other ice and by the National Science Foundation's same areas taken over time. Office of Polar Programs. shelves are also changing. Cooperation with other Antarctic mapping groups now To compile a comprehensive inventory An extensive archive of early 1970's includes scientists from Italy, Russia, of named (from published maps, Landsat 1, 2, and 3 Multispectral Scanner Norway, Canada, . Argentina, and gazetteers, and compact discs) and (MSS) images of Antarctica was the impetus Germany. unnamed (from analysis of Landsat

Planned USGS 1-2600 Maps:

A-Trinity Peninsula B-Larsen Ice Shelf C-Palmer Land D-Ronne Ice Shelf E-Eights Coast F-Bakutis Coast (1997) G-Saunders Coast H- l-Ross Island 90°W 90°W 90°E J-Drygalski Ice Tongue K-Oates Coast L-George V Coast M-Banzare Coast N-Knox Coast O-Queen Mary Coast P-Amery Ice Shelf Q- R-Mawson Coast S-Prince Olav Coast T-Princess Ragnhild Coast U-Fimbul Ice Shelf V-Cape Norvegia W-Caird Coast X-Berkner Island 180°W

Figure 1. Index map to the principal geographic features of Figure 2. Index map showing the locations and names of the 24 planned 1:1,000,000- Antarctica, including the ice shelves where large coastal- scale coastal-change and glaciological maps of Antarctica. The first (prototype) map, change events commonly occur. I-2600-F, "Coastal-Change and Glaciological Map of the Bakutis Coast, Antarctica: 1972-1990," was published by the U.S. Geological Survey in 1997.

U.S. Department of the Interior USGS Fact Sheet FS 050-98 U.S. Geological Survey May 1998 images) outlet glaciers and ice streams Velocities of floating glaciers (such as For more information, please contact: in Antarctica that are mappable from glacier tongues, ice streams, ice shelves) are Landsat and other satellite images. determined by two methods: (1) an interac­ Richard S. Williams, Jr. To publish the results of the analyses in tive one in which crevasse patterns are U.S. Geological Survey 24 maps as I-2600-A-X of the USGS traced visually on images and (2) an auto­ Woods Hole Field Center Geologic Investigations Series (I-Maps) correlation program developed by the U.S. 384 Woods Hole Road (fig. 2). Each 1:1,000,000-scale map National Aeronautics and Space Admin­ Woods Hole, MA 02543-1598 extends to the southernmost nunatak istration (NASA). The larger glacier tongues Telephone: 508-457-2347 within each map area or to the ­ and ice shelves have well-developed rift pat­ Fax:508-457-2310 ernmost extent of Landsat images terns that can be used for velocity measure­ E-mail: [email protected] (about 81.5°S. lat.). The 1:1,000,000- ments. Under optimum conditions, errors scale maps will be combined to pro­ can be as small as ±0.02 km per year, but or duce a l:5,000,000-scale map of for most Landsat image pairs, where regis­ Antarctica. tration of features is not as accurate, the Jane G. Ferrigno accuracy of velocity vectors is ±0.1 km per U.S. Geological Survey Ice fronts, tongues, and glacier tongues are the most dynamic and change­ year. A third method for calculating ice sur­ 955 National Center able features in the coastal regions of face velocity using satellite radar interfer- 12201 Sunrise Valley Drive Antarctica. Seaward of the grounding line, ometry has been developed by scientists at Reston,VA20192 the floating ice margin is subject to frequent the California Institute of Technology (Jet Telephone: 703-648-6360 and large calving events or rapid flow. Both Propulsion Laboratory) and NASA and Fax: 703-648-6524 of these situations lead to annual and decadal offers promise in some areas. E-mail: [email protected] changes in the position of ice fronts on the Producing a sophisticated glacier inven­ order of several kilometers, even tens of The Coastal-Change and Glaciological tory of Antarctica according to the require­ kilometers in extreme cases of major calving Maps of Antarctica effort is being done ments of the World Glacier Monitoring events (fig. 3). under the Glacier Studies Project of the Service, as part of its ongoing "World Processes and Regional Impacts component On the coastal-change and glaciological Glacier Inventory" program, is impossible of the Global Change and Climate History maps, the positions of the dynamic ice fronts with the present state of glaciological Program, USGS Global Change Research as observed on remotely sensed data have knowledge about Antarctica. Landsat and Program. For more information, visit the been mapped and annotated with the date of other images and available maps are used in World Wide Web site at each position. This record makes it possible the compilation of the coastal-change and http://geochange.er.usgs.gov to analyze changes that have occurred. glaciological maps to produce a reasonably Although calving does occur along ice walls, complete preliminary inventory of named the magnitude of the change on an annual to and unnamed outlet glaciers and ice streams decadal basis is generally not discernible on and also to define, more accurately, related the images; therefore, ice walls can be used glaciological features such as ice domes, ice as relatively stable reference features against piedmonts, ice shelves, ice rises, ice rum­ which to measure other changes along the ples, glacier tongues, and iceberg tongues. coast. Only a single observation date is given for the position of ice walls.

64 KM

Figure 3. Left, Landsat MSS image of margin of the Filchner Ice Shelf, , West Antarctica, on 11 November 1973. Right, Landsat MSS image of the same area on 18 October 1986 after a major calving event.