Abstract from: 'An inventory of present glaciers on Heard Island and their historical variation' by Andrew Ruddell.
Heard Island is a large ice-covered volcanic cone situated in the south Indian Ocean. Its location enables unique climatic information to be obtained from a very remote and predominantly maritime region. Past studies show that while some glaciers have undergone major recession since the late 1940s, others, such as large non-calving glaciers, have shown little change in extent. The island is usually cloud covered and this has hampered aerial and ground based surveys. Using SPOT satellite imagery acquired in 1988 and supplemented by aerial photography in 1987 and a digital elevation model derived from 1997 Radarsat imagery, an inventory of glacier extent is provided and this indicates that there are a total of 29 glaciated basins (41 termini), with an area of 257 km2 and an estimated volume of 14.2 km3. The satellite imagery is used to rectify earlier estimates of glacier extent based on aerial photography in 1947 and 1980. Between 1947 and 1988 the glaciated area had decreased by 11% and volume by 12%. Approximately half of this occurred during the 1980s. A variety of historical records have been compiled and these provide evidence of glacier behaviour since the mid-1800s when they were at their greatest extent during the recorded period. The elevation range of a glacier is a good indication of glacier hypsometry and its sensitivity to mass balance and climate variations. Glaciers such as the Gotley are of large elevation range and high mass turnover. Such glaciers show little sensitivity to climate variations as they lose much of their ice through calving into the sea rather than surface melt. Glaciers of low elevation range such as those on the Laurens Peninsula are especially sensitive to climate change. Glaciers of this type indicate that while minor decadal fluctuations have occurred in the period from at least 1902 to the 1950s, the recession of many glaciers during the past 50 years has been unprecedented. The glacier variations correlate with observed temperature records. Observations of occasional volcanic eruptions since the 1880s indicate that most activity is related to lava flows from Mawson Peak and fumerole activity on its upper southwestern slope. This activity appears to have had little effect on the Gotley and Lied glaciers.