An Aerial View of ~100 Years of Glacier and Ice Cap Change in South Greenland

Authors: Laura J Larocca*, Northwestern University, Yarrow L Axford , Northwestern University, Anders A Bjørk, Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen
Topics: Cryosphere, Earth Science, Climatology and Meteorology
Keywords: Greenland, Arctic, glacier, climate change, air photo, remote sensing
Session Type: Poster
Day: 4/4/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: No File Uploaded

In addition to the Greenland Ice Sheet, Greenland’s outlying glaciers and ice caps (covering ~90,000 square kilometers) will contribute substantially to sea-level rise this century. As long-term, in-situ mass balance measurements on Greenlandic glaciers are rare, most studies on glacier change have been restricted to the satellite era. We investigate longer-term fluctuations of local glaciers and ice caps in South Greenland using a unique archive of Danish air photos. This archive of 180,000 aerial photographs documents the frontal positions of Greenlandic glaciers beginning in the early 20th century with the historic Seventh Thule Expedition. We combine the air photos with early (Corona) and modern (Landsat and Sentinel) satellite imagery to measure frontal positions and glacier lengths over the past ~100 years. We also infer Little Ice Age (LIA) extent from moraines and trim lines, where visible. End-of-melt-season air photos were digitized, orthorectified, and georeferenced for comparison with the late 20th and early 21st century satellite imagery. Terminus change was calculated via the variable box method and multi-centerline method using the Margin change Quantification Tool (MaQiT). Preliminary results suggest that South Greenland’s glaciers have responded on a decadal scale to periods of warming and cooling, with fastest retreat in the early 20th century after the LIA, followed by low retreat rates (possibly in response to mid-twentieth century cooling), and increasing retreat rates in the early 21st century. Ultimately, this study aims to improve estimates of glacier sensitivity to 21st century projected warming.

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