GlobGlacier: Mapping the worlds glaciers and icecaps from space for improved climate change impact assessment

Changes of glaciers and ice caps are key indicators of climatic change, mostly due to their enhanced and well recognizable reaction to small climatic changes. Glaciers and ice caps have thus been selected as one of the essential climatic variables (ECVs) in the global climate observing system (GCOS) and their monitoring has been organized in a tiered strategy within the global terrestrial network for glaciers (GTN-G). Within GTN-G, annual measurements of mass balance (about 50 glaciers at Tier 2 and 3) and length changes (550 glaciers at Tier 4) are performed. Detailed glacier inventory data (Tier 5) from the 1960s to 1970s exist as point information in the world glacier inventory (WGI) for about 71'000 glaciers, which is c. 40% of the estimated 160'000 glaciers worldwide. Thus, (1) the current sample of glaciers with annual measurements is very small and presumably not representative for the changes at a global scale and (2) the WGI is far from being complete and difficult to use for change assessment (point data). As melting glaciers and ice caps might provide an even larger contribution to global sea level rise than the two ice sheets, their is an urgent necessity to generate more complete and representative data sets.

While the large potential of multispectral satellite data for glacier mapping is already utilized by the GLIMS initiative to create a digital database of glacier outlines, the full potential of satellite data for determination of glacier mass balance or length changes in a systematic way remain to be explored. As the required techniques for mapping glacier snow lines, topography, elevation changes or velocity fields (all indicative for mass balance) do already exist, one remaining challenge is their integrated and systematic application to a large set of glaciers. The here presented new ESA project GlobGlacier aims at exploring and applicating the existing methods to already archived satellite data in order to contribute to existing databases (GLIMS, WGMS) and programs. GlobGlacier is one of ESAs data user element (DUE) activities that responds to the needs of some major users groups, which are actively involved in defining the products and assessment of the service.

In this contribution we describe the products that will be generated by GlobGlacier, their mutual dependencies and the available methodologies. We further illustrate the organization of the project (workpackages) and the proposed schedule for the deliverables. We conclude with an overview of the expected results and their relevance for future glacier monitoring and change assessment.