Bajo del Plomo Glacier in 2018 and 2022 Sentinel images illustrating the lack of any retained snowpack in 2022 and the expansion and emergence of bare rock areas amidst the glacier at Point A-D.

Bajo del Plomo Glacier at 7 km in length is one of two large glaciers at the headwaters of the Rio Plomo, Argentina, which is a tributary to Rio Tupungato and then Rio Mendoza. Glaciers in this region have lost ~30% of their area since 1955 (Malmros et al 2016). The majority of runoff to the Rio Plomo in summer is from snowmelt, with glaciers becoming more critical by late summer (Masiokas et al 2006)..  In February of 2022 with no snow evident in the upper basin on or off the glaciers, glaciers will dominate the runoff into the Rio Plomo  Earlier observations indicate this is a regional issue this summer with snowpack lost from Cortaderal Glacier, Palomo Glacier, Volcan Overo Glacier and Olivares Beta and Gamma Glaciers across the Central Andes of Chile and Argentina. Here we examine Sentinel and Landsat imagery to identify the lack of snowpack in summer 2021/22 on Bajo del Plomo Glacier and the expansion of bare rock areas.

Bajo del Plomo Glacier terminates at 4100 m and has two main accumulation zones that extend from 4600-5000 m near PointB and C respectively. In February 2018 there is limited bedrock expose near Point B and C, while Point A has two principal bedrock exposures with an area of   0.12 km². In 2018 the snowline is at 4600 m.  The Dec. 21, 2021 Sentinel image indicates that the snowline is already at 4800 m. By January 18, 2022 Sentinel imagery indicates less than 10% of the upper glacier above 4900 m has retained snowcover.  By February 8, 2022  a Landsat 9 images indicates that all the snowpack on the glacier and surrounding area has been lost. The darker ice/firn surface of the glacier melts faster than a snow covered glacier surface leading to thinning and expansion of bedrock area including new exposures at Point B and D.  The area of exposed rock at Point A has doubled to 0.24 km², and bedrock exposed at Point C is notably expanded too. The emergence of bedrock amidst the accumulation zone of a glacier is indicative of a glacier that cannot survive current climate as it is not consistently retaining snowpack (Pelto, 2010).

With a month left in the melt season Bajo del Plomo will continue to lose area and volume.

Bajo del Plomo Glacier in 2021 and 2022 Sentinel images illustrating the loss of snowpack from Dec. 21, 2021 to January 18, 2022 and the expansion and emergence of bare rock areas amidst the glacier at Point A-D.

Landsat 9 Image from Feb. 8, 2022 illustrating lack of retained snowpack.