Changes in Heard Island glaciers, king penguins and fur seals since 1947

Abstract

The purpose of this paper is to summarise and discuss the changes in glaciers, king penguins and fur seals reported by the nine wintering parties and 11 summer expeditions that have visited Heard Island since 1947, with emphasis upon those of the years between 1947 and 1971. These early years were notable for an initial period (1947-55) of minimal change, and a subsequent period(1963-71) of rapid change in which a complex pattern of asynchronous glacier retreat and readvance was observed and the main features of the island's recolonisation by king penguins and fur seals were established. Subsequent expeditions have reported continuing glacier recession, evidently in response to warmer air temperatures, and a continuing exponential increase in king penguins and fur seals. The glacier observations show that the Heard Island glaciers are sensitive indicators of climate change in the Southern Ocean, and of the interactions between climate and glacier topography. The island's recolonisation by king penguins and fur seals is attributed mainly to an improved food supply which may itself, like the glacier recession, be a response to changes in atmospheric and oceanic circulation. Glacier recession and its consequences are changing the island's coastline, and the expanding populations of king penguins and fur seals are damaging the vegetation. All these phenomena, occurring as they do in an island with a hitherto undamaged ecosystem and no introduced predators, clearly warrant continuing study.

Glacier retreat and melt-lake expansion at Stephenson Glacier, Heard Island World Heritage Area

“…Regions that show melting without pond formation remain relatively unchanged de spite the increase in SST (Scambos and others 2000). Glacier retreat on both Heard Island and nearby Kerguelen conforms broadly to a similar atmospheric warming trend (Frenot and others 1993;Garvin and others 1999;Budd 2000). MAT at Heard Island increased 1.8°C between 1948 and 1951 and remained 1.3°C higher in the middle 1950s.…”

“…Recession of these glaciers over the last half-century has been attributed to a rise in atmospheric air temperatures and a steady rise in sea-surface temperature (Radok and Watts 1975;Allison and Keage 1986;Budd 2000). Glaciers that originate low on Big Ben have shown the most marked recession during historicaltime because they have a low mass flux and a high proportion of their total area at low altitude, and are therefore sensitive to a balance shift (Ruddell and Allison 1997).…”

“…Observa tions in 1965, 1969, and 1971 indicated generally continu ing retreat, although some re-advance occurred between 1963 and 1971 (Budd 1970;Budd and Stephenson 1970;Allison and Keage 1986). In 1971 a lake several hundred metres wide was present between the ice edge and north eastern Dovers Moraine, from which a large stream flowed down a meltwater channel to the coast beside the present day ANARE Spit Camp (Budd 2000;G. Budd, personal communication, 26 April 2001).…”

“…Some asynchronous retreat and advance of different gla ciers took place during the following decade (Budd 1973(Budd , 2000, after which continuing recession occurred (Allison and Keage 1986;Garvin and others 1999;Kiernan and McConnell 1999;Green 2000).…”

Major eruption-induced changes to the McDonald Islands, southern Indian Ocean

“…Flat Island, however, was seen to be deserted. King penguins (Aptendoytes patagonica), which have been rapidly recolonizing Heard Island since the late 1950s (Budd 2000), were not seen on the McDonald Islands in either 1971 or 1980 -possibly because the steepness of the rocky coast had prevented them from gaining access to suitable habitat. In November 2002, however, photographs indicate large colonies of some thousands of King penguins with large chicks -many of them grouped in separate crèches -behind and to the north of Thelander Point (Fig.…”