Search

The Desert Andes contain >4500 ice masses, but only a handful are currently being monitored. We present the mass changes of the small mountain glacier Agua Negra (1 km2) and of the rest of glaciers in the Jáchal river basin. Remote-sensing data show Agua Negra glacier lost 23% of its area during 1959–2019. Glaciological measurements during 2014–2021 indicate an average annual mass balance of −0.52 m w.e. a−1, with mean winter and summer balances of 0.80 and −1.33 m w.e. a−1, respectively. The Equilibrium Line Altitude (ELA) is estimated to be 5100 ± 100 m a.s.l., which corresponds to an Accumulation Area Ratio (AAR) of 0.28 ± 0.21. Geodetic data from SRTM X and Pléiades show a doubling of the loss rate from −0.32 ± 0.03 m w.e. a−1 in 2000–2013, to −0.66 ± 0.06 m w.e. a−1 in 2013–2019. Comparatively, the ice losses for the entire Jáchal river basin (25 500 km2) derived from ASTER show less negative values, −0.11 ± 16 m w.e. a−1 for 2000–2012 and −0.23 ± 14 m w.e. a−1 for 2012–2018. The regional warming trend since 1979 and a recent decline in snow accumulation are probably driving the observed glacier mass balance. [ABSTRACT FROM AUTHOR]

Over the last 2 decades the importance of Andean glaciers, particularly as water resources, has been recognized in both scientific literature and the public sphere. This has led to the inclusion of glaciers in the environmental impact assessment and the development of glacier protection laws in both Chile and Argentina. However, these laws are limited in their ability to protect, manage, and monitor water resources as they do not differentiate between glacier types. We propose three glacier categories that aim to group glaciers based on their sensitivity to environmental changes as a framework that could be adopted to match the level of protection to the current and future needs of society, be region-specific, and evolve through time. Finally, we review both national inventories with respect to this classification to facilitate the evaluation and/or management of water resources. [ABSTRACT FROM AUTHOR]

High glacial mountain environments around the world are important water reservoirs and are extremely sensitive to the effects of climate change. Considering that climate change affects snow accumulation and glacial melting, it is essential to understand the runoff generation and hydrological dynamics in these type of systems. Andean glaciers have shown a retreating and thinning pattern since the start of the 21st century. Regarding this, the stable isotopic composition of waters is useful to assess the contributions from different sources (i.e., glaciers, precipitation, and tributaries' inputs) to rivers. Several Patagonian mountain rivers have Andean glaciers in their headwaters, one of which is the Manso River. In this basin, over the last 30 years, the Ventisquero Negro Glacier (Manso Glacier's regenerated tongue) experienced a rapid thinning and recession that generated a proglacial lake, called Manso proglacial Lake. In this study, topographic effects upon the stable isotopic composition of river waters (δ2H and δ18O) are recognized, particularly, the altitude effect. The stable isotope composition of the Manso River varies downstream, evolving to a composition more enriched in heavy isotopes in the lower basin, likely due to altitude effects and the progressive evaporation that mainly occurs in the lakes' surfaces that the river crosses. Results show that glacial meltwater is the major water contributor in the upper basin during early fall. In the rest of the basin the stable isotopic composition of the Manso River is mainly controlled by the lakes' isotopic signatures and is highly influenced by two tributary rivers. The concordance between isotopic models and hydrological data demonstrates that stable isotopes constitute a valuable tool to quantify the contribution of different water sources. This has the potential to be particularly useful in areas where discharge data is unavailable. [ABSTRACT FROM AUTHOR]

The quantification of volumetric ice and water content in active rock glaciers is necessary to estimate their role as water stores and contributors to runoff in dry mountain catchments. In the semi-arid to arid Andes of Argentina, active rock glaciers potentially constitute important water reservoirs due to their widespread distribution. Here however, water storage capacities and their interannual changes have so far escaped quantification in detailed field studies. Volumetric ice and water content was quantified using a petrophysical four-phase model (4PM) based on complementary electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) in different positions of the Dos Lenguas rock glacier in the upper Agua Negra basin, Argentina. We derived vertical and horizontal surface changes of the Dos Lenguas rock glacier, for the periods 2016–2017 and 2017–2018 using drone-derived digital elevation models (DEMs). Interannual water storage changes of - 36 mm yr -1 and + 27 mm yr -1 derived from volumetric surface changes for the periods 2016–2017 and 2017–2018, respectively, indicate that significant amounts of annual precipitation can be stored in and released from the active rock glacier. Geophysical results show heterogeneous ice and water content with ice-rich permafrost and supra-, intra- and sub-permafrost water pathways at the end of the thaw period. Active layer and ice-rich permafrost control traps and pathways of shallow groundwater and thus regulate interannual storage changes and water releases from the active rock glaciers in the dry mountain catchment. The ice content of 1.7–2.0 × 10 9 kg in the active Dos Lenguas rock glacier represents an important long-term ice reservoir, as do other ground ice deposits in the vicinity, if compared to surface ice that covers less than 3 % of the high mountain catchment. [ABSTRACT FROM AUTHOR]

Glaciers and the periglacial environment in Argentina have been protected by the Law since 2010. This legislation required the development of the first National Glacier Inventory (NGI), which was officially presented in May 2018 and based on satellite images spanning between 2004 and 2016. Here, we present the methods and results of the NGI, summarize the glaciers' morphological and spatial characteristics, and compare our results to previous regional and global inventories. The NGI reveals an impressive variety of ice masses including rock glaciers, permanent snowfields, mountain and valley glaciers with varying amounts of debris-cover and large outlet glaciers. The Argentinean Andes contain 16 078 ice masses covering an area of 5769 km2 between 200 and 6900 m a.s.l. Comparison of the combined national inventories of Argentina and Chile (~30 000 glaciers and 28 400 km2) with the Randolph Glacier Inventory 6.0 for the Southern Andes (~16 000 glaciers and 29 400 km2), shows that there are large differences in extent and number of glaciers in some sub-regions. The NGI represents an improvement for a better understanding of Argentina's freshwater reservoirs and provides detailed information for the preservation and study of ice masses along 4000 km of the Southern Andes. [ABSTRACT FROM AUTHOR]

Among glacier instabilities, collapses of large parts of low-angle glaciers are a striking, exceptional phenomenon. So far, merely the 2002 collapse of Kolka Glacier in the Caucasus Mountains and the 2016 twin detachments of the Aru glaciers in western Tibet have been well documented. Here we report on the previously unnoticed collapse of an unnamed cirque glacier in the Central Andes of Argentina in March 2007. Although of much smaller ice volume, this 4.2±0.6×106 m 3 collapse in the Andes is similar to the Caucasus and Tibet ones in that the resulting ice avalanche travelled a total distance of ∼2 km over a surprisingly low angle of reach (∼5 ∘). [ABSTRACT FROM AUTHOR]