Ice thickness of Comox and Kokanee Glaciers, British Columbia, determined through relative gravity surveys

Abstract. Ice thickness data are sparse or lacking for many glaciers worldwide, making it difficult to track changes in ice volume due to ongoing climate change. In this study, we collect and model relative gravity survey data, to provide the first estimate of ice thickness for the retreating Comox Glacier, a historically important source of freshwater for eastern Vancouver Island, British Columbia. We validate our approach by carrying out a similar analysis across the Kokanee Glacier, for comparison with recent ice penetrating radar results. Modelling of the Bouguer gravity anomaly across each glacier provides an average inferred ice thickness of 42 ± 4 m across a 450 m transect of Comox Glacier, and 50 ± 3 m across a 220 m transect of Kokanee Glacier, consistent with previous measurements. Future repeat surveys will enable monitoring of ice thickness changes over time. Compared to other methods, gravity surveying offers a lower cost and logistically simpler alternative for the collection of ice thickness data on glaciers worldwide.