When a time series of suitable images are available for a certain region, changes in glacier length and extent can be calculated. "Such data allow scientists to assess the overall pattern of changes in a larger region for a better determination of climatic change impacts," said GlobGlacier Project Manager Frank Paul from the University of Zurich.
The above animation, based on data acquired by Landsat's TM on 15 November 1990 and by ETM+ on 1 August 2001, illustrates the changes in glacier extents that occurred during this time in the region northeast of the Gangotri Glacier, situated in Garwhal Himalaya.
While most of the smaller and debris-free glaciers show considerable retreat in this period, the larger glaciers with completely covered tongues have not changed much. Several of the pro-glacial lakes have grown. Quite a few glaciers at lower altitudes are nearly free of snow in the August 2001 image, indicating a retreat that year.
ESA's ERS-1, ERS-2 and Envisat Advanced Synthetic Aperture Radar (ASAR) data are providing velocity measurements of selected glaciers. The image to the right shows the surface velocity field for the Baltoro Glacier in Pakistan based on Envisat ASAR data from 2003 to 2008.
ESA's new Climate Change Initiative, which will produce robust long-term records of essential climate variables, will build on the results of the GlobGlacier project by further improving the algorithms for glacier monitoring and continually updating the related glacier inventory information.
|Contact: Mariangela D'Acunto|
European Space Agency