Changes in area of Heard Island Glaciers - measured from satellite images, 2012-2016

Brief description

The glaciers on Heard Island have continued to retreat over the past decade. There have been several aerial surveys of the glaciers on Heard Island. The first was in the 1940’s where it was reported that the glacierised area of the island was 288 km2 but by the 1980’s it had decreased to 256 km2 (Ruddell 2006). In the early 2010’s this had decreased further to 236 km2 in 2012 and again to 235 km2 in 2014. The most recent survey from 2016 of the larger Big Ben glaciers (i.e., Baudissin, Challenger, Downes, Ealey, Compton, Brown, Fifty-One, Gotley, and Lied glaciers) indicated that there has been an additional decrease in area of these larger glaciers since the 1940’s.

Examination of more recent satellite images of the eastern glaciers, indicates that these leeward glaciers continue to retreat at greater rates then those on the windward side of the island. For example, in the last two Australian Government State of the Environment reports Brown Glacier has been reported to have retreated from 6.2 km2 in 1947 to 4.4 km2 in 2004, a loss of 29% and again decreasing to 3.6 km2 in 2008 (Harris 2009; Lucieer er al. 2009), to 3.5km2 in 2014 (Donoghue 2017), and to 3.4 km2 in 2016, a total loss since 1947 of 45%. As of January 2019 Brown Glacier has continued to retreat.

Four sets of GEOeye-1 images were purchased by the Australian Antarctic Division (AAD) from Digital Globe in 2016 and again in 2017. There were two images available for 2 February 2012, three images for 6 February 2014, three images for 21 February 2016 and two for 2 March 2017.

The purchased GEOeye images were orthorectified by Geo Image and made available through the AAD Data Centre.
The outlines of the glaciers were digitised using QGIS (3.10) using the UTC WGS 1984 zone map projected coordinate system for this region. Polygon shapefiles were created along the terminus of the glaciers and to outline any rock outcrops or other non-glacial features. The non glacial features areas were removed from the final area calculations.
Areas and lengths were calculated using QGIS area and measure calculation tools.