Halving of Swiss glacier volume since 1931 observed from terrestrial image photogrammetry

Abstract. The monitoring of glaciers in Switzerland has a long tradition, yet glacier changes during the 20th century are only known through sparse observations. Here, we estimate halving Swiss volumes between 1931 and 2016 by mapping historical elevation at high resolution. Our analysis relies on terrestrial image archive as TerrA, which covers about 86 % glacierised area with 21 703 images acquired period 1916–1947 (with median date 1931). We developed semi-automated workflow to generate digital models (DEMs) from these images, resulting 45 total coverage. Using geodetic method, Swiss-wide mass balance ?0.52 ± 0.09 m w.e. a?1 2016. This equates 51.5 8.0 loss volume. find that low-elevation, high-debris-cover, gently sloping termini conducive particularly losses. In addition glacier-specific, quasi-centennial changes, present new inventory outlines timestamps complete attributes around 1931. fragmented spatial coverage temporal heterogeneity TerrA largest sources uncertainty our glacier-specific estimates, reaching up 0.50 a?1. suggest high-resolution surface elevations could also unlock great potential for research fields other than glaciology.