January 12, 2018
Glaciar Olvidado (O) retreat illustrated in 1985 and 2017 Landsat images. Red arrow is 1985 terminus location, yellow arrow is 2017 terminus location and purple dots are the snowline. This illustrates an 1800 m retreat.
Glaciar Olvidado (G) is a glacier in the southeast portion of the Southern Patagonia Icefield (SPI), adjacent to Grey Glacier (G). The glacier terminates in a proglacial lake. Rivera and Casassa (2004) report the glacier terminating in a newly formed lake in 1986 and retreating slowly from 1986 to 2000. Here we examine changes in the glacier from 1985 to 2017 using Landsat imagery.
In 1985 the glacier terminates in small newly formed proglacial lake that is just 200 m long. The snowline in 1985 is at 1050 m. In 2000 the lake has expanded to a length of 900 m. The snowline in 2000 is at 950 m. By 2016 the proglacial lake has expanded to a length of 2 km. The snowline in 2016 is at 1100 m. In 2017 the glacier has retreated 1800 m since 1986. The snowline is at the base of the steep slopes at 1150 m. The high snowline leaves less than 30% of the glacier in the accumulation zone. The high snowlines indicate a limited accumulation zone, which generates a negative mass balance and drives retreat. The glacier continues to calve into this terminus lake adding to the negative mass balance and consequent retreat. This glacier adds to the growth of proglacial lakes seen in the Northern Patagonia Icefield (Glasser et al 2016) and SPI (Iribarren et al 2014). Olvidado Glacier retreat in terms of distance is similar to the adjacent Grey Glacier, but does represent 20% of its total length. The retreat is much less than the HPS-12 glacier on the west side of the SPI.
Olvidado Glacier in 2016 Google Earth image.