| 23 Jun 2026
Robust attribution of global industrial-era glacier mass loss to anthropogenic climate change
Abstract. We apply formal climate-attribution methods to industrial-era glacier mass loss at both regional and individual glacier scales. Using a combination of observed temperatures and climate-model simulations, we show that warming across all glacierized regions of the globe is attributable to anthropogenic climate change. Our central estimates are that the magnitude of the anthropogenic warming over the industrial era ranges from from 91–98 % of the observed, depending on region. These temperature changes equate to regional equilibrium-line-altitude (ELA) rises of 107–340 m, all of which are at least extremely likely anthropogenic in origin.
We examine 75 individual glaciers around the world, using realistic geometries and mass-balance profiles to reconstruct approximate preindustrial glacier geometries. Using these preindustrial geometries as reference surfaces, we analyze mass balance on these surfaces and show that anthropogenic ELA rise has produced sweeping changes in ablation and accumulation across all sampled glaciers. We find that a glacier's sensitivity to ELA rise is governed more strongly by local catchment geometry than by climatic setting. Since these industrial-era mass-balance changes are driven by the anthropogenic warming, our central estimates of the anthropogenic contribution are the same as for temperature.
Finally, we compare these anthropogenically driven changes against the distribution of natural mass-balance variability drawn from both climate-model counterfactual simulations and last-millennium reconstructions at each of our 75 glaciers. Across all glacierized regions, it is virtually certain the anthropogenic mass-balance signal is outside the envelope of natural variability, as characterized by both preindustrial climate reconstructions and the CMIP counterfactual ensemble. Within our analysis framework, we conclude it is very likely that anthropogenic warming is the primary driver of industrial-era mass loss.
This paper usefully quantifies, labels, and clearly states the anthropogenic contribution to changes in melt-season air temperatures (as the primary driver of glacier melt and indeed overall mass loss), Equilibrium Line Altitudes (ELAs), and glacier mass balance for two time periods (pre-industrial to modern and last millennium) using a couple of methods, from extracting temperatures from global datasets to flowline modeling with OGGM. It does all of the above first for Argentiere as a case study; the simpler analysis is then done for all glaciers globally, while the flowline modeling is done for a subset of 75 glaciers for which the necessary data are available.
I appreciate this work and find no major flaws in it, insofar as my technical expertise allows. The authors have done a service in using the standardized IPCC language, and in clearly and directly stating their results in these terms. I think many readers, some glaciologists included, will find things are even worse than we thought!
I have only minor comments that are included in the form of an annotated pdf, with the exception that I found the overall structure of the manuscript confusing. Unless this work was first submitted to a short-form journal and only lightly reformatted, I cannot understand the current structure, which progressively reveals methods as the paper goes along. The final section, as an example, is a bit sprawling and includes new results, some discussion, and summary statements. This reader would very much appreciate a more standardized format, though this does not exclude the possibility of interleaving methods and results provided there is a clear outline of what’s to come early on in the paper.
In addition to cleaning up the structure, or the wayfinding at the very least, a more explicit articulation of some of the methods would be appreciated. For example, I don’t think the temperature data are ever downscaled from their native resolution of 1 degree, but I’m not sure. Similarly, I think the method of relating air temperature to ELA is so simple that I did not get it at first; or maybe it’s not simple and I still don’t get it? Please state explicitly what is done or express the calculation unambiguously as an equation. In the spirit of clear communication, many would also appreciate if the standard mass-balance terminology and notation (as enshrined in the Cogley et al. Glossary) were used in such a paper where mass balance is of central importance.
Thanks for an interesting and important analysis! I’m sure I will be using or referring to this paper when it’s published.