A Google Earth Engine Tool for Mapping Key Metrics of Glacier Health from Space

Kara Ann Lamantia, Laura Larocca, Rainey Aberle, Fabien Maussion, James M Lea

Satellite-based observations enable monitoring of glacier health metrics, essential for assessing glacier response to climate change and the environmental services they provide. Here, we present a Google Earth Engine tool for automated mapping of key climate- and mass balance- modulated parameters, including total visible ice area, snow-covered area (SCA), accumulation-area ratio, and snowline altitude (often used as a proxy for the equilibrium-line altitude). The tool uses Landsat near-infrared reflectance, commonly used spectral band ratios, and scene-specific thresholding to distinguish snow-covered from ice or firn surfaces. Validation for 60 glaciers across 13 regions shows strong agreement with manual observations of satellite imagery and weaker agreement with field-based observations from the World Glacier Monitoring Service (WGMS), likely reflecting differences in methodology and observation timing. The tool substantially improves WGMS temporal coverage, filling ~63% of glacier-year gaps and increasing the total number of observations (e.g., SCA by ~65%). Beyond the glaciers studied here, the tool is designed to enable efficient and accessible generation of multi-decadal glacier health time series for individual glaciers globally, with appropriate user evaluation and consideration of known limitations. Thus, the tool will hold value for a range of academic and non-academic users, particularly for education, outreach, and community stakeholders.