Ice thickness and subglacial topography of Swedish reference glaciers revealed by radio-echo sounding

Abstract. Sweden currently hosts 270 glaciers, four of which belong to the 61 reference glaciers monitored worldwide. Eight Swedish glaciers disappeared during the warm summer of 2024, and under the global warming scenario associated with current climate policies, all four Swedish reference glaciers (Mårmaglaciären, Storglaciären, Rabots glaciär, and Riukojietna) are projected to vanish within this century. Such change will have implications for people, ecosystems, infrastructure, and local meteorological processes, highlighting the need to better constrain the resultant emerging post-glacial landscapes. During 2024–2025, we conducted radio-echo sounding (RES) surveys on the four Swedish reference glaciers and obtained a total of 40470 ice thickness point measurements. The mean and maximum measured ice thicknesses are 97 and 242 m for Mårmaglaciären, 88 and 225 m for Storglaciären, 85 and 158 m for Rabots glaciär, and 32 and 87 m for Riukojietna. The corresponding mean ice-thickness uncertainties are 12.0, 12.4, 11.4, and 7.5 m, respectively. The RES-measured ice thicknesses were used to produce high-resolution (10 m × 10 m) maps of ice thickness distribution and subglacial topography for each reference glacier, and to calculate their ice volumes as 0.32 (Mårmaglaciären), 0.25 (Storglaciären), 0.23 (Rabots glaciär), and 0.10 km3 (Riukojietna). The RES data for the four reference glaciers are available at https://doi.org/10.17043/tarfala-marma-res-survey-1, https://doi.org/10.17043/tarfala-storglaciaren-res-survey-1, https://doi.org/10.17043/tarfala-rabot-res-survey-1, and https://doi.org/10.17043/tarfala-rivgojiehkki-res-survey-1 (Wang et al., 2026b, d, a, c). The ice thickness and subglacial topography for the four reference glaciers are available at https://doi.org/10.17043/tarfala-marma-res-2, https://doi.org/10.17043/tarfala-storglaciaren-res-2, https://doi.org/10.17043/tarfala-rabot-res-2, and https://doi.org/10.17043/tarfala-rivgojiehkki-res-2 (Wang et al., 2025a, d, b, c).