03 Nov 2023
 | 03 Nov 2023
Status: this preprint is open for discussion.

Assessing the glacier projection uncertainties in the Patagonian Andes (40–56° S) from a catchment perspective

Rodrigo Aguayo, Fabien Maussion, Lilian Schuster, Marius Schaefer, Alexis Caro, Patrick Schmitt, Jonathan Mackay, Lizz Ultee, Jorge Leon-Muñoz, and Mauricio Aguayo

Abstract. Glaciers are retreating globally and are projected to continue to lose mass in the coming decades, directly affecting downstream ecosystems through changes in glacier runoff. Estimating the future evolution of glacier runoff involves several sources of uncertainty in the modelling chain, which to date have not been comprehensively assessed on a regional scale. In this study, we used the Open Global Glacier Model (OGGM) to estimate the glacier evolution of each glacier (area > 1 km2) in the Patagonian Andes (40–56° S), which together represent 82 % of the glacier area of the Andes. We used different glacier inventories (n = 2), ice thickness datasets (n = 2), historical climate datasets (n = 4), general circulation models (GCMs; n = 10), emission scenarios (SSPs; n = 4), and bias correction methods (BCMs; n = 3) to generate 1,920 possible scenarios over the period 1980–2099. For each scenario and catchment, glacier runoff and melt on glacier time series were characterized by ten glacio-hydrological signatures (i.e., metrics). We used the permutation feature importance of random forest regression models to assess the relative importance of each source on the signatures of each catchment. Considering all scenarios, 61 % ± 14 % of the catchment area (30 % ± 13 % of glacier area) has already peaked in terms of glacier melt (year 2020), and 43 % ± 8 % of the catchment area (18 % ± 7 % of glacier area) will lose more than 80 % of its volume this century. Considering the melt on glacier signatures, the future sources of uncertainty (GCMs, SSPs and BCMs) were the main source in only 18 % ± 21 % of the total catchment area. In contrast, the reference climate was the most important source in 78 % ± 21 % of the catchment area, highlighting the importance of the choices we make in the calibration procedure. The results provide a basis for prioritizing future efforts (e.g., improve reference climate characterization) to reduce glacio-hydrological modelling gaps in poorly instrumented regions, such as the Patagonian Andes.

Rodrigo Aguayo et al.

Status: open (until 19 Dec 2023)

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Rodrigo Aguayo et al.


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Short summary
Predicting how much water will come from glaciers in the future is a complex task, and there are many factors that make it uncertain. Using a glacier model, we explored 1,920 scenarios for each glacier in the Patagonian Andes. We found that the choice of climate data was the most important factor, while other factors such as different data sources, climate models and emission scenarios played a smaller role.