Reply to “Comment on attribution of modern Andean glacier mass loss requires successful hindcast of pre-industrial glacier changes”

Abstract

In a recent paper (Lüning et al., 2022; henceforth L22) we critically commented on an attribution study by Stuart-Smith et al. (2021; hencefort S21), pointing out a mismatch between numerical simulation and palaeoclimatological reconstruction data on pre-industrial glacier length. The authors of S21 have now written a comment on our discussion (hencefort S23) to which we reply here. We are surprised to learn that S23 assume we have presented manipulated data. We will show in the following that this allegation is entirely baseless. It is unfortunate that S21 failed to include any pre-industrial palaeoclimate data in their original attribution study, especially as S21 attempted to regionally quantify anthropogenic vs. natural contributions to glacier length change. It should be common practice to initially study pre-industrial natural climate variability in depth to better understand natural climate dynamics for a precedent period without major anthropogenic influences. The discussion of L22 is based on a thorough review of the Medieval Climate Anomaly (MCA; 1000–1200 CE) based on 76 terrestrial and marine sites in South America (Lüning et al., 2019a), including detailed site descriptions and illustrations in a 49 page-long supplementary material. The review concluded that “the vast majority of all South American land sites suggest a warm MCA“. Our South American MCA review forms part of a series of papers on the MCA encompassing various parts of the world, namely Africa/Arabia (Lüning et al., 2017, 2018), Antarctica (Lüning et al., 2019b), Oceania (Lüning et al., 2020), and the Mediterranean region (Lüning et al., 2019c). All of these papers have been published in international, reputable, fully peer-reviewed journals. We, therefore, feel that we are fully qualified to comment on the MCA.