Estimating ice retreat on Greenwich island – Antarctica between 1956 and 2019 using optical and SAR imagery

Abstract

The Antarctic Peninsula and the adjacent South Shetland Islands show a significant atmospheric warming trend. Increase in air temperature is commonly associated with glacier melting. However, there is a dearth of documentation about the glaciers of Greenwich Island. This study fills a knowledge gap about glacier melting on Greenwich Island by focusing on four glaciers located on the northern part of it. We also update the temperature trends and analyze the relationship between glaciers melting and temperature changes. We used airborne, optical and SAR satellite sensors along with in-situ measurements over the 1956–2019 period to map glaciers extent changes. The total ice cover of these glaciers decreased from 10.01 km2 in 1956 to 7.97 km2 in 2019, i.e. 20.4%. The results suggest a glacier loss rate of 32359 m2/year (−0.32%/year). This rate of loss is coherent with other measurements made in the South Shetland Islands. We also update the air temperature rising trend in this area to +0.23 °C/decade between 1966 and 2018 at Chile's Arturo Prat base. We do however find two significant trends over the last sixty years: +0.36 °C per decade between 1966 and 1998 and a sharp decrease between 1998 and 2015 of −0.6 °C per decade.