Ice-front change and iceberg behaviour along Oates and George V Coasts, Antarctica, 1912-96

Ice-front change may well be a sensitive indicator of regional climate change. We have studied the western Oates Coast from Cape Kinsey (158°50'E, 69°19'S) to Cape Hudson (153°45'E, 68°20'S) and the entire George V Coast, from Cape Hudson to Point Alden (142°02'E, 66°48'S). The glaciers here drain part of the Dome Charlie and Talos Dome areas (640 000 km2). A comparison between various documents, dated several years apart, has allowed an estimate of the surficial ice discharge, the ice-front fluctuation and the iceberg-calving flux during the last 50 years. The ice-front discharge of the studied coast has been estimated at about 90±12 km3 a-1 in 1989-91, 8.5 km3 a-1 for western Oates Coast and 82 km3 a-1 for George V Coast. From 1962-63 to 1973-74 the floating glaciers underwent a net reduction that continued from 1973-74 to 1989-91. On the other hand, from 1989-91 to 1996 the area of floating glaciers increased. Ninnis Glacier Tongue and the western part of Cook Ice Shelf underwent a significant retreat after 1980 and 1947, respectively. Satellite-image analysis of large icebergs has provided information about ice-ocean interaction and the existence of an 'iceberg trap' along George V Coast. A first estimate of the mass balance of the drainage basin of Mertz and Ninnis Glaciers shows a value close to zero or slightly negative.