Recent changes in the glaciers of Heard Island

Abstract

ABSTRACTHeard Island, a heavily glacierized volcanic island in the Southern Ocean, is 80% ice-covered, with glaciers descending from 2,400 m to sea level: major glaciers are up to 7 km long with areas exceeding 10 km. Much of the island was photographed from the air in 1947 and again in early 1980. Photographs and limited ground surveys record changes (mostly retreats) in glacier fronts. Retreat is most marked on the eastern flanks where former tidewater glaciers are now grounded inland. Glaciers on northern and windward western flanks still end in ice cliffs but have narrowed; glaciers and ice caps on Laurens Peninsula (maximum elevation 710 m) are up to 65% smaller. Nearby lies Kerguelen and other southern islands with long climatic records have warrned significantly since the early 1960s. Surface and upper-air climatic data from Heard Island 1947–54 and records from automatic weather stations 1980–82 suggest that Heard too has warmed slightly, concurrently with a possible northward shift of low-pressure system tracks in this region. Temperatures have remained above average through the early 1980s and glacier retreat is expected to continue.