Cook Ice Cap – Dramatic melting raises concern

The Cook Ice Sheet is the largest French glacier found more than twelve thousand kilometers from the Alps, in the Kerguelen Islands. In 1963, the Cook ice cap had an area of ​​about 500 square kilometers. Glaciologists have observed the increasingly rapid contraction of the French glacier using recently collected satellite data.

Over the past four decades, scientists have witnessed the Cook Ice Sheet thinning by about 1.5 meters each year. The decrease in the area of ​​the glacier has been around 20%. Glacier retreat has been recorded to have been twice as fast since 1991. This research on the shrinkage of this ice sheet was published in the Journal of Geophysical Research.

Initial studies of Cook Cap melting showed a slow initial retreat of Ampere Glacier, which is one of the outlet glaciers of the Cook Cap, between 1800 and 1965, which subsequently became much faster. In situ monitoring of the French Glacier has not been carried out since 1974. However, observations made from space between 1991 and 2006 have allowed scientists to collect data on the French Glacier, which is located in a rather inaccessible area.

Glaciologists began their studies of the French glacier by compiling a complete inventory of the glaciers found on the Kerguelen Islands. At that time, these glaciers covered more than 700 square kilometers, including the 500 square kilometers occupied by the glacier alone.

The scientists then used Spot and Landsat satellite imagery to update this inventory for the years 1991, 2001, and 2003, as well as to quantify the glacial retreat of the Cook Ice Sheet. In 1991, the glacier covered 448 square kilometers, the area of ​​which had shrunk to 403 square kilometers in 2003. In total, the French glacier has lost 20% of its surface in 4 decades and has rapidly retreated twice as fast since 1991. In addition, the scientists were able to estimate the volume loss, or mass balance, of the glacier over the past 4 decades.

This mass balance provides an accurate characterization of the response of this glacier to climatic variation (temperature and precipitation) and can be used in comparisons of glacial responses for various regions on earth. For example, the Cook Ice Sheet has thinned by 300 to 400 meters in the low-lying glacier tongues, while thickness variations appear smaller in the higher regions.