November 15, 2017
HPS-12, Chile Spectacular 13 km retreat 1985-2017
Posted by Mauri Pelto
HPS-12 Glacier in 1985 and 2017 Landsat images. The red arrow indicates 1985 terminus, yellow arrows the 2017 terminus, purple dots the snowline and 1-4 are tributaries. By 2017 all tributaries have detached and the glacier has retreated 13 km.
HPS-12 is an unnamed glacier draining the west side of the Southern Patagonia Ice Cap (SPI). The glacier terminates in a fjord and is adjacent to Upsala Glacier to the east and Pio IX Glacier to the north. This developing fjord is also unnamed but feeds into Estero Falcon. The glaciers of the SPI have been experiencing significant mass loss and overall retreat. Willis et al (2012) observed significant mass loss from 2000-2012 of −20.0 Gt per year. Willis et al (2012) indicate in Fig.1 that the majority of the ice cap has thinned during this period from 2-10 m, with the greatest thinning being in the lower portion of HPS-12. Schaefer et al (2015) indicate and ELA of 980 m and a calving velocity of 2290 m per year, which is quite high for this size of glacier. Here we examine the retreat and fjord opening using Landsat imagery from 1985-2017. Is it the fastest retreating glacier in Chile in the last three decades?
In 1985 the HPS-12 terminates 1.5 km from the junction of two fjords that are occupied by HSP-12 and HSP-13. These are separated by a peninsula. The glacier is fed by four tributaries labelled 1-4. The snowline in 1985 is at 900 m. In 2001 the four tributaries still join the main glacier, but the terminus has retreated 3.5 km. In 2015 glacier retreat has led to separation of tributary 1, 2 and 4 from the main glacier, tributary 3 only feeds tributary 2 and not the main glacier. The snowline in mid-January of 2015 is at 950 m. The glacier retreat has continued to 2017, the current terminus is 800 m wide vesus 2800 m wide in 1985 at this location. total retreat from 1985 to 2017 is 13 km. The fjord is now nearly 15 km long. HPS-12 was 26 km long in 1985 and is now less than 13 km long, it is 1/2 gone in three decades. This retreat along with Jorge Montt is the largest in Chile in the last 30 years. The retreat fits the pattern of large retreats of calving outlet glaciers of SPI such as Onelli Glacier, Bernardo Glacier and Lucia Glacier.
We also have a unique laboratory to examine a pristine fjord just created an the aquatic ecologic succession and physical oceanographic transitions that will occur.
HPS-12 Glacier in 2001 and 2015 Landsat images. The red arrow indicates 1985 terminus, yellow arrows the 2017 terminus, purple dots the snowline and 1-4 are tributaries. By 2015 all tributaries have detached.
HPS-12 in 2015 Digital Globe image. Red dots indicate 1985 terminus and yellow dots 2015 terminus location for main glacier and tributaries.