Remote sensing of glacier change on Disko Island, Nuussuaq Peninsula and Svartenhuk Halvø (West Greenland) since the Little ice age

Category GIS & Remote sensing
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Citterio, Michele۱; Paul, Frank۲; Ahlstrّm, Andreas P.۱; Jepsen, Hans F.۱; Weidick, Anker۱
Holding Date 08 October 2008

Glacier retreat from the end of the Little Ice Age (LIA) to the year 2001 has been quantified on Disko Island, Nuussuaq Peninsula and Svartenhuk Halvø using multispectral satellite imagery, aerophotogrammetric topographic maps and glacier inventory records.
We mapped the outlines of glaciers and ice caps in 2001 by first producing thresholded ratio images from Landsat ETM+ bands 3 and 5, and subsequently by manually correcting for occasional misclassifications (lakes, snow fields), or for glacier tongues with a supraglacial debris cover masking the underlying glacier ice. The maximum LIA glacier extents have been mapped from the Landsat ETM+ scenes by visually interpreting the trimlines, and using the plates from the Glacier Inventory and Atlas of West Greenland as an aid in the area south of 71° N. Topographic maps from 1984 have also been overlaid for comparison, and we present our results in terms of glacierized area changes both from the LIA to 2001 and, where available, for the sub-periods LIA-1984 and 1984-2001.
The general trend shows a marked decline in the glacierized area after the LIA and at places, especially on Disko Island, the incipient disintegration of larger glaciers into several entities. A strong retreat (comparable to the European Alps) of many valley or outlet glaciers has also been observed. We first discuss our results with reference to the glacier sample taken as a whole, and then we compare the changes of glaciers belonging to different size classes. The difficulties posed by the presence of surge-type glaciers, which are quite common on Disko Island, will be apparent from the examples shown.
The geospatial datasets produced during this work, and consisting mainly of verified glacier outlines from West Greenland, are a contribution to the GLIMS Project. As a regional center for Greenland within the GLIMS Project and member of the users group within the GlobGlacier Project, the National Geological Survey of Denmark and Greenland (GEUS) is actively supporting the mapping of glacierized areas in various parts of Greenland, either by directly running the complete workflow leading from the multispectral satellite scene to the vectorization of glacier outlines, or by carrying out validation work against other spatial datasets already available within GEUS itself.
Glaciers and ice caps in the Arctic are expected to experience a particularly marked temperature increase in the coming decades. At the same time, most of the required basic methods for producing glacier outlines from multispectral satellite data have matured from the experimental stage into a "production-ready" stage. A more comprehensive archive of digital outlines from local glaciers and ice caps on Greenland may therefore be attainable within a reasonable time frame.