The recent IPCC report discussion of the cryosphere noted medium confidence among experts in the belief that as much as one quarter of the world's mountain glacier mass would disappear if climate projections for 2050 were realized. Current trends show little change in some mountain glaciers and significant change in others. The report goes on to describe possible impacts associated with this and other cryosphere-related changes to include changes in seasonal water availability, altered landscapes, and changes in carbon dioxide and methane released to the atmosphere. Internationally coordinated glacier monitoring has been going on for over a century, and during the last several decades satellites have greatly improved monitoring capabilities (Fitzharris, 1996). To improve confidence in the understanding of the dynamic nature of glaciers and the impacts of changes in them, the NASA Pathfinder Program is using existing satellite-based data sets to study global change. Scientists studying glaciers have been directly involved in the levels and types of processing and end-to-end management needed to generate consistent products from satellite data for the user community. Examples of Pathfinder data sets include those generated by the Advanced Very High Resolution Radiometer (AVHRR) aboard NOAA weather satellites and the Thematic Mapper (TM) and Multispectral Scanner (MSS) instruments carried on the Landsat series of satellites. Data gathered by several instruments planned for the Earth Observing System component of Mission to Planet Earth in addition to synthetic aperture radar (SAR) data can also be used to monitor glaciers. Careful reprocessing of existing data from these instruments is paramount to ensure the greatest accuracy possible for comparison of changes in glaciers over time. Landsat images have been used to measure ice flow rates, as well as glacier advance and retreat. SAR data enables monitoring unencumbered by cloud cover and solar illumination conditions. Understanding the spatial and temporal variations in the responses of glaciers to changes in climate is critical to understanding their sensitivity to climate. The advantages of using remote sensing technology to monitor glaciers are evident in the ability to monitor hard-to-access or inaccessible glaciers and the ability to expand the spatial and temporal coverage required to compile sufficient empirical evidence of glacier dynamics. Data sets documenting these changes are valuable to climate modelers and researchers investigating the consequences of global change.

Reference:

Fitzharris, B.B., 1996, The cryosphere: Changes and their impacts; in Climate Change 1995, Impacts, adaptations and mitigation of climate change: scientific-technical analyses; Intergovernmental Panel on Climate Change: New York, Cambridge University Press, p. 241-260.