glenglat: A database of global englacial temperatures

Abstract. Measurements of englacial temperatures have been collected since the earliest years of glaciology, with the first measurements dating back to the mid-19^th century. Although temperature is a defining characteristic of any glacier – and is notoriously laborious to collect – no effort had yet been made to gather all existing measurements. In an attempt to make existing ice temperature data more accessible, we present glenglat, a global database of englacial temperature measurements, compiled from 241 literature sources and nine data submissions and composed of 1142163 measurements of depth and temperature from 690 boreholes located on 186 glaciers outside of the ice sheets. Alongside recent compilations for the ice sheets (Løkkegaard et al., 2023; Vandecrux et al., 2023), most published englacial temperature measurements are now readily available to the research community.

Here, we review the variety of glacier thermal regimes that have been measured and summarize the spatial, temporal, and climatic coverage of measurements relative to global glacierized area. Measurements of cold and polythermal glacier ice greatly outnumber those of temperate ice. Overall, temperature has been measured in fewer than 1 ‰ of all glaciers, and only 20 % of borehole locations have been measured more than once, highlighting the large potential to investigate changing temperature conditions by repeating past measurements. The database is developed on GitHub (www.github.com/mjacqu/glenglat) and published to Zenodo (https://doi.org/10.5281/zenodo.13334175; Jacquemart and Welty, 2024). It consists of four relational tables and detailed machine-actionable and human-readable metadata. The GitHub repository also provides submission instructions (including a spreadsheet template and validation tools), in the hopes that investigators can help us keep glenglat complete and current going forward. We hope that glenglat can help improve our understanding of glacier thermal regimes, help refine glacier thermo-dynamic models, or shed insight into hazardous glacier instabilities in a warming world.