Everest South Col Glacier did not thin during the period 1984-2017

The South Col Glacier is a small body of ice and snow (approx. 0.2ĝ€¯km2) located at the very high elevation of 8000ĝ€¯mĝ€¯a.s.l. (above sea level) on the southern ridge of Mt. Everest. A recent study by proposed that South Col Glacier is rapidly losing mass. This is in contradiction to our comparison of two digital elevation models derived from aerial photographs taken in December 1984 and a stereo Pléiades satellite acquisition from March 2017, from which we estimate a mean elevation change of 0.01ĝ€¯±ĝ€¯0.05ĝ€¯mĝ€¯a-1. To reconcile these results, we investigate some aspects of the surface energy and mass balance of South Col Glacier. From satellite images and a simple model of snow compaction and erosion, we show that wind erosion has a major impact on the surface mass balance due to the strong seasonality in precipitation and wind and that it cannot be neglected. Additionally, we show that the melt amount predicted by a surface energy and mass balance model is very sensitive to the model structure and implementation. Contrary to previous findings, melt is likely not a dominant ablation process on this glacier, which remains mostly snow-covered during the monsoon.