AAR_THAR_AABR-ELA

This repository contains the code and data used to reproduce the simulations, data analysis, and figures of Yang, W., Mackintosh, A.N., Cooper, EL. et al. Global estimates of glacier equilibrium-line altitude ratios for enhanced paleoclimate reconstructions. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03391-5. We estimate of AAR0, THAR0, and AABR0 ratios for nearlly all modern glaciers on Earth using a hybrid of Python Glacier Evolution Model (PyGEM v0.2.5), developed by David Rounce and collaborators, and Open Global Glacier Model (OGGM v1.6.0), developed by the OGGM community. Glacier AAR0 was calculated by completing linear regression of simulated annual mass balances and AARs from 1995 to 2014 and by a steady-state assumption method. ELA0, THAR0 and AABR0 were estimated for each glacier based on AAR0 and the glacier geometry from the Randolph Glacier Inventory 6.2. We then analyze the influence of climatic, topographic, and glacier-intrinsic factors (e.g., glacier types and glacier area) on AAR0, THAR0, and AABR0, thereby identifying systematic variations in ELA ratios across groups of glaciers with similar characteristics. Based on this analysis, we develope a decision-tree-based classification tool, “Glacier ELA Ratio Calculator” (GERC), to estimate AAR0, THAR0, and AABR0 values for groups of glaciers with similar characteristics based on key glacier and climate variables. The web-based version of the GERC is available on Streamlit. Although we also provide the AAR0, ELA0, THAR0, and AABR0 of global modern glaciers in the NetCDF file results_all_mad_debriscalving.nc and in the directory /results_all_mad_debriscalving_csv, we still recommend the users to use "GERC" for the more robust estimates at the group level, rather than for individual glaciers. Please find more details and the code used to generate figures and tables at our GitHub repository and README.md. If you use these data in your research, please cite: Yang, W., Mackintosh, A.N., Cooper, EL. et al. Global estimates of glacier equilibrium-line altitude ratios for enhanced paleoclimate reconstructions. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03391-5. Dataset DOI: https://doi.org/10.5281/zenodo.18737031