Integration of reconstructed front variations into the glacier database of the WGMS

The standardization of glacier front variations is designed to allow seamless comparison between reconstructions and in-situ observations while still providing the most relevant information on methods and uncertainties of the individual data series. The standardized compilation of in-situ observations is straightforward: the change in glacier front position is determined between two points in time and supplemented by information on survey dates, methods and data accuracies. The reconstruction of palaeo-glacier front positions and their dating is usually more complex and based on multiple sources of evidence. Spatial uncertainty can arise from ambiguous identification of the glacier terminus, while temporal uncertainty is associated with the dating technique used in each case.

The concept of integration of reconstructed front variations into the relational glacier database of the WGMS was jointly developed by natural and historical scientists. The glacier reconstruction data are stored in two data tables. The first table contains summary information of the entire reconstruction series including a figure of the cumulative length changes, investigator information, and references. The second table stores the individual glacier front variation data, minimum and maximum glacier elevation, and metadata related to the reconstruction methods and uncertainties. The metadata are stored in a combination of predefined choices of methods and open text fields. This ensures a standardized description of the data, but also provides space for individual remarks. Both data tables are linked by a unique numeric glacier identifier to the main table of the WGMS database with general information of the present-day glacier. This database relationship enables the direct comparison of reconstructed with observed front variations.

A more detailed description of the integration of glacier reconstructions into the WGMS database can be found in PAGES News 19(2).

For the submission of reconstructions of glacier front variations, please read the corresponding Notes on the Completion of the Data Sheets for reconstructed front variations and use the Digital Data Submission Form, or contact us directly.