How have the Glaciers & Ice Fields of South Georgia Island Changed in Recent Decades?

• Main Author: Webster, Rob
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: The University of Edinburgh 2020
• Subjects: South Georgia, geodetic mass balance, glacier, climate change, ice field, SRTM, TanDEM-X, SAR, Interferometry; Southern Ocean; South Georgia Island
• Online Access: https://dx.doi.org/10.7488/era/903; https://era.ed.ac.uk/handle/1842/37622

South Georgia, in the midst of the Southern Ocean, is a mountainous island approximately 170 km long and up to 35 km in breadth. It is largely covered in ice-fields and glaciers that are responding to climatic changes. This study extends the work of Cook et al. 2010 and Gordon et al. 2008 by investigating recent changes to 70 glacier fronts using Sentinel 2 and Landsat 8 imagery. Ice elevation change was investigated by differencing digital elevation models (DEMs) generated from TanDEM-X data, NASA’s Shuttle Radar Topography Mission (2000) and TanDEM-X 90m datasets. 68 of the glaciers studied were found to be retreating, in one case as rapidly as −349ma 1 over the last ten years. Two glaciers have stable frontal positions. The average rate of front retreat (since records began) is −27ma 1. North coast glaciers are receding faster with mean rates of −43ma 1. South coast glaciers are retreating at the lower rate of −15ma 1 on average. Particularly noticeable is the accelerating recession of marine-terminating glaciers towards the southeastern end of the island, likely linked to increasing sea surface temperatures. The island as a whole was found to have lost mass at a rate of −1.91 ± 0.36 Gt a 1 in the period 2000 to 2012. Detailed analyses in a study area of 360 km2 are produced for 2000-2011 and 2012-2015. The former shows substantial mass loss due to ice thinning. The latter suggests substantial areas with increasing ice elevation around the period 2012-2015 which requires further investigation. Finally, results from glacier frontal change and ice mass balance area are drawn together, with a discussion of possible driving factors.