World Glacier Inventory — Inventaire Mondial Des Glaciers

World Glacier Inventory — Inventaire mondial des Glaciers (Proceedings of the Riederalp Workshop, September 1978; Actes de l'Atelier de Riederalp, septembre 1978): 1AHS-AISH Publ. no. 126, 1980. West Greenland outlet glaciers: an inventory of the major iceberg producers R.C. Koilmeyer Abstract. By an international treaty between 22 nations involved in North Atlantic shipping, the United States Coast Guard has been assigned a statutory mission to act as the International Ice Patrol. The International Ice Patrol was formed shortly after the iceberg sinking of the RMS Titanic. Ice Patrol duties include studies of the current conditions affecting the drift and persistence of icebergs in the North Atlantic Ocean and the glacial origin of the ice. In 1968 the US Coast Guard commenced an examination of the major iceberg producing glaciers along the west coast of Greenland. This programme, called the West Greenland Glacier Survey, is attempting to visit and revisit every major outlet glacier along the western edge of the ice sheet. Terminus locations have been surveyed along with height measurements on 27 major outlet glaciers. A total of 59 glaciers have been photo-documented. Most of the glaciers exhibit retreat. Les glaciers émissaires du Groenland occidental: un inventaire des principaux producteurs d'icebergs Résumé. Un traité international signé entre 22 pays engagés dans le commerce maritime de l'Atlantique Nord a confié à la Garde Côtière des EU la mission d'agir en tant que Patrouille Internationale des Glaces. Cette patrouille a été créée à la suite du naufrage du RMS Titanic, survenu à la suite d'une collision avec un iceberg. Les tâches de la Patrouille des Glaces comprennent l'étude des conditions actuelles qui influencent la dérive et la durée de vie des icebergs dans l'Atlantique Nord et l'étude de la provenance des glaces. En 1968, la Garde Côtière des Etats Unis à commencé à examiner les glaciers qui produisent la plupart des icebergs le long de la côte ouest du Groenland. Ce programme, nommé 'Surveillance des Glaciers du Groenland occidental', prévoit de visiter et de revisiter tous les principaux glaciers émissaires situés le long de la limite ouest de la banquise. On a observé la position et l'altitude du front des 27 principaux glaciers émissaires. Au total, on a réuni des documents photographiques sur 59 glaciers. La plupart des glaciers semblent se trouver dans une période de recul. BACKGROUND. Icebergs produced along the West Greenland coast are carried by winds and currents to the Canadian shore and then south by the Labrador current to the Grand Banks of Newfoundland. The Grand Banks have been traversed by transatlantic shipping for centuries. These transiting vessels have always been menaced by icebergs and prevalent fog particularly in the spring and early summer. In 1912 the RMS Titanic struck an iceberg and sank with a great loss of life. One year later in London the International Conference on Safety at Sea established the International Ice Patrol. In 1914 the United States Coast Guard assumed these responsibilities and commenced patrolling the Grand Banks of Newfoundland each spring, reporting the iceberg presence to passing ships and has continued this service to the present day. From the first ice patrol, the Coast Guard also undertook a systematic series of océanographie and ice studies. By 1928, these studies included the glacier origins of the icebergs. Coast Guard expeditions to Western Greenland were carried out between 1928 and 1935 and identified 21 glaciers which make major contributions to iceberg occurrence in the North Atlantic Ocean. Average annual production rates for these glaciers were estimated and glacier front advances or retreats were determined qualitatively within the limits of available information. 57 58 R. C. Kollmeyer Some 33 years later in 1968 the West Greenland Glacier Survey was established to resume the research of the sources of the North Atlantic icebergs. The decades of the 1950s and 1960s showed a decline in the mean number of icebergs drifting into the Grand Banks Ice Patrol area. The decline was precipitous in comparison to the steady iceberg populations during the preceding 50 years. Future planning and budgeting for International Ice Patrol as well as planning for the possibility of greater arctic shipping activities required a re-inspection of the general productivity of the glaciers that produce the icebergs which hazard shipping. Trends during the first half of the 1970s turned out to be the reverse of the 1950s and 1960s. 1972 became the greatest year ever for icebergs on the Grand Banks and 1974 ended up to be the second greatest year on record. Conflicting interpretations of these data are clearly possible, e.g. advancing glaciers, abnormal meteorological conditions or a catastrophic breakup of the great floating ice tongues of West Greenland. Obviously, information of this sort is required for the planning and budgeting of the International Ice Patrol. METHODS The region of study lies between 69° 10'N off Disko Island and 81°30'N in Hall basin. This region includes Jakobshavn as the southernmost glacier of interest and Petermann's as the furthest north. The following objectives of the West Greenland Glacier Survey are being pursued: (1) To survey the West Greenland iceberg-producing tidewater glaciers and compare the data thus obtained with earlier records to ascertain the advance or recession of the glaciers, changes in iceberg production rates, and future trends. (2) To determine the total annual number of icebergs calved from the major West Greenland glaciers and the regularity of production to allow further investigation of the causes of variations in the annual number of icebergs found on the Grand Banks. (3) To survey the environmental conditions affecting the discharge and drift seaward of icebergs from the parent glaciers. This includes fjord configuration, sill depth and coastal circulation. (4) To provide a carefully obtained pictorial and data documentation of the present state of the outlet glaciers of the last continental ice sheet in the Northern Hemisphere for scientific use in the future. The procedures generally followed for the survey of an outlet glacier are: (1) Conduct a helicopter flight from a Coast Guard icebreaker standing by near the glacier to select sites from which physical measurements of the glacier can be made. Place one or two survey parties ashore to make the following observations and measurements: (a) Locate the survey site by using visual landmarks and establish a metallic marker (benchmark) to which all data are referenced. (b) Optically survey the glacier terminus using a theodolite and laser range- finder. Due to the size of some glaciers, triangulation is necessary from two different survey sites. (c) Measure optically the height of the calving terminus at as many points as possible. Measure floating tabular icebergs when present. (d) Make observations concerning: recently unglaciated or overrun terrain near the glacier, tidal markings on terminus, calving activity and freshness of the calving surface, iceberg population and fresh ice near the terminus, the presence of upwelling meltwater immediately in front of the glacier, streaming zones and noise. Sketch the glacier, mark the site with a rock cairn. (2) Concurrently, complete a detailed photographic overflight by helicopter. West Greenland outlet glaciers 59 (3) Conduct océanographie observations from the Icebreaker including fjord bathymetry, sill depth determination and coastal and fjord water properties. Variations in these procedures are often made depending on the glacier and the situation. Many minor glaciers are only photographed. RESULTS Surveys have been conducted during the summers of 1968-1971, 1976 and 1978. A total of 27 major iceberg-producing glaciers have been extensively surveyed from the ground and 59 have been photographed from aircraft. Table 1 lists the glaciers for which survey data have been obtained. All the glaciers listed have been documented by photographs. A second visit to each of the major glaciers has commenced. Two more expeditions are planned to complete the project. TABLE 1. Glaciers visited Glacier Surveyed Glacier Surveyed Umiamako X Rinks X Great Karajak X Little Karajak - X Eqip X sextant angles Avangnarelleq (2) X Kujatdleq X (Torssukatak) Jakobshavn X Gade's X Helland Wulff Yngvar Nielson Mohn Unnamed! (Carlos) MoreË Docker Smith X Pearys X Kong Oscar X Nansen X Dietrichson X Sverdrup Steenstrup X Kjears Hayes X Giesecke X Upernavik X Cornell Ussings Nordenskiolds Humboldt X Petermann's X Bissels Morris Jesup X Clements Markham Diebitsch Meehan Verhoeff Sun Bowdoin X Tracy X Heilprin X Farquaar Academy (Leidy) X Petowik (Pitugfik) X Sermeissuaq (Moltke) X Knud Rassmussan Agpat Hart Sharp Melville Savage Berlingske Hurlbut Chamberlin Brother Johns Dodge San Martin Hubbard High altitude (2424 m) stereo-overlapping vertical photography of all glaciers from Jakobshavn north to the Humboldt Glacier was accomplished during the years 1968- 1970 with annually repeated coverage for particular glaciers. It is possible to give only a brief summary of the accomplishments to date. An enormous amount of data have been collected since 1968. An attempt is made herein to try to indicate the type and scope of the information obtained. Time and space permit only a short examination of several of the more interesting outlet glaciers. Starting with the southernmost glacier of interest, Jakobshavn is certainly one of the most impressive. It has been in a state of recession since first monitored in 1850 60 R. C. Kollmeyer (Fig. 1) with several minor advances. (Bauer, 1968). The glacier is presently some 50 km from the fjord's mouth. The fastest moving portion of the glacier is confined to the northern side with the wider southern portion filling an embayment. A slight rise occurs in the southern part leading to the suspicion that land will soon emerge in the form of a nunatak if recession continues.

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