1. Jakobshavn Isbrae Glacial Retreat
Casey Horgan and Erin Cowles

2. Project Goals
Analyze the retreat of the Jakobshavn Isbrae glacier over at least the last 20 years
Estimate the additional freshwater input to oceans due to retreat
Analyze land cover change in areas where glacier has retreated
Climate change impact on retreat?

3. The Glacier Location Characteristics Widely studied Greenland
Western Greenland near town of Ilulissat
Approximate latitude of 70 degrees N
Characteristics
Greenland’s largest outlet glacier
Drains 6.5% of total ice sheet area
Fastest flowing glacier in the world
Flow rate doubled between 1997 and 2003
Distinct calving mouth that forms 40 km ice fjord/tongue
Widely studied
Glacier dynamics
Effects of Climate Change
climatechange.umaine.edu
Google Earth

4. Data and Images Landsat 5 and 7 Images Google Earth
From 1985, 2001, 2007, 2009, 2011
All images from month of July, with exception of 1985 (Sept)
No images available from October 1992 to October 1997
Google Earth
Used for reference dataa
Ilulisat Climate Record
Only goes back to 1988
Preprocessing
Subsets with area coverage of 94.8 km E-W by 40.1 km N - S

5. Classifications Classes
Glacier, Fjord Ice, Icebergs, Glacial Pools, Open Water, Barren/Uncovered Land, Vegetative Land
Similarities between glacier, ice sheet, fjord ice, and icebergs
Spectral signatures
Boundaries
Locations
Unsupervised and two supervised classifications
Highly inaccurate

8. Simple Random Accuracy Assessment of the Seven Class Supervised Image

10. Digitizing More appropriate and accurate than classifying
Land covers digitized
Glacier
Recently uncovered/barren land
Fjord ice/tongue of glacier
Extent of connected ice only
Digitizing provided ability to…
Calculate change in coverage areas of the glacier and ice sheet
Measurement of glacier retreat
Visual representation of glacier and tongue retreat
Amount of land recently uncovered by the retreat
Estimate amount of fresh water added to oceans from Jakobshavn retreat

12. Area Analysis Calculations
Did area calculations in ArcMap, using the vector files created when digitizing
Had to do unions between image pairs for 1985 and 2001, and 2007, 1985 and 2009, 1985 and 2011, 2001 and 2007, 2007 and 2009, and finally 2009 and 2011
Then clipped to the area of the glacier and used attribute table to find amount of change

13. Table of Area Calculations

14. Table of Ice Sheet Area Calculations

15. Jakobshavn Isbrae Changes
Retreated by square kilometers, which is just over 64 square miles
If estimate that the glacier is 1.1 meter thick, this inputs million cubic meters of water.
47.8 square kilometers of subglacial land, the rest is lakes, or part of the ice fjord
The subglacial land appears to be rocky with sparse or no vegetation
Vegetation coverage seems to increase as exposure time increases

17. Conclusions
Since we have not done a thorough accuracy assessment, we would not use our information for more detailed projects
However, we can conclude that the glacier has retreated significantly from 1985 to the present. 
In addition, our analysis can be applied to other glaciers around the world to see how climate change may be impacting their growth or retreat.

18. Questions?