Learning from Alfred Wegener’s pioneering field observations in West Greenland after a century of climate change

The cryosphere in Greenland is currently undergoing strong changes. While remote sensing improves our understanding of spatial and temporal changes across scales, particularly our knowledge of conditions during the pre-satellite era is fragmented. Therefore, high-quality field data from that period can be particularly valuable to better understand changes of the cryosphere in Greenland at climate time scales. At Graz University, the last work-place of Alfred Wegener we have access to the extensive expedition results from their epic 1929–1931 expedition to Greenland. The expedition coincides with the warmest phase of the Arctic early twentieth century warm period. We present an overview of the main findings of the Wegener expedition archive and set it into context with further monitoring activities that occurred since, as well as the results from reanalysis products and satellite imagery. We find that firn temperatures have increased significantly, while snow and firn densities and have remained similar or decreased since. Local conditions at the Qaamarujup Sermia have changed strongly, with a reduction in length of more than 2 km, in thickness by up to 120 m and a rise in terminus position of approximately 300 m. The elevation of the snow line of the years 1929 and 1930 was similar to the one from the extreme years 2012 and 2019. Compared to the satellite era, we find that during the time of the Wegener expedition fjord ice extent was smaller in early spring and larger in late spring. We demonstrate that a well-documented snapshot of archival data can provide a local and regional context for contemporary climate change and that it can serve as the basis for process-based studies on the atmospheric drivers of glacier changes.