Decadal Area Changes of Arctic Glaciers using Object-Based Image Analysis in Google Earth Engine: Session C52A-04

Climate change has had a significant impact on glacier recession worldwide, contributing disproportionately to global sea-level rise. Due to Arctic amplification, glaciers in the Arctic are retreating faster than at lower latitudes. To better understand the impact of climate change on glaciers in the Arctic, observations of temporal changes in glacier extent are necessary, but these observations are not widely available due to the large effort required in accurately mapping glacier area. In this study, we mapped 1208 glaciers in Disko Island (Qeqertarsuaq), Greenland and Novaya Zemlya, Russian Arctic, using Object-Based Image Analysis (OBIA) applied to multispectral Landsat satellite imagery in Google Earth Engine (GEE) to quantify the glacier area changes over three decades. In 1986-89, the total glacierized area in Novaya Zemlya was 22990±301 km2, in 2000-01 the area was 22525±308 km2, and by 2019-21 the glacier area was 21670±292 km2, a 5.73% reduction in area between 1986-89 and 2019-21 - three glaciers covering an area of 6.44±0.08 km2 were entirely retreated. On Disko Island, the glacierized area was 1929±127 km2 in 1985, 1769±127 km2 in 2001, and 1472±110 km2 in 2019, a 23.6% decline in area during 1985-2019, and 110 glaciers (18.02±1.19 km2) are retreated completely. Land-terminating glaciers on Novaya Zemlya lost a total glacierized area of 580±130 km2 (7.9%), compared to 457±168 km2 (23.6%) on Disko Island. The accuracy of the automatically generated outlines was evaluated by comparing with manually corrected outlines (reference data) using a random sampling approach, resulting in an overall accuracy estimate between 96% and 97% with the reference data. This indicates that the method used in GEE has the potential for rapid glacier mapping and can be easily used in other glacierized regions.