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December 20, 2021

Hindle Glacier Retreat Causes Rapid Opening of Fjord, South Georgia

Posted by Mauri Pelto

Hindle Fjord opening comparison in 2009, 2015 and 2021 Landsat images.  Point A is the northern tributary, Point B the middle tributary, Point C separates the eastern and western tributary and Point D is Ross Glacier.

Hindle Glacier enters Royal Bay on the east coast of South Georgia Island.  The British Antarctic Survey (BAS) has been the  examining glacier change on South Georgia Island, Cook et al (2010) noted a pattern island wide with many calving glaciers having the fastest retreat.  Alison Cook (BAS) identified that 212 of the Peninsula’s 244 marine glaciers have retreated over the past 50 years and rates of retreat are increasing.  In 2017 we examined Landsat imagery from 1989 to 2017 to identify the rapid retreat rate of Hindle Glacier. NASA Earth  piggy backed on this assessment, with excellent imagery, since the retreat rate has increased. Here we focus on the formation of the fjord from 2009-2021.

For Ross-Hindle Glaicer in 1989 the glaciers joined 2.5  km from the terminus spanning Royal Bay with a 3.2 km wide calving front.  By 2001 the glacier front had retreated 800 m, but was still a single joined calving front. By 2009 the glaciers had separated due to an additional retreat of  1.4 km. The Hindle Glacier front was now retreating south up opening a new separate fjord from Ross Glacier.  The calving front in 2009 was 1.6 km wide.  By 2015 a 1.6 km retreat led to the separation of Hindle from the northern tributary, Point A.  From 2015 to 2019 the main terminus retreated another 2.1 km, passed the middle tributary at Point B, to a prominent rock knob, Point C, separating the two main tributaries of the glacier with total retreat of  6.1 km in 30 years, an exceptional rate of over 200 m/year. The western tributary is at the head of the fjord and no longer calves significantly, while the eastern tributary has another 1 km to an increase in slopes that likely is close to head of the fjord. The new fjord is 4.5 km long and averages 1.1 km in width and has an area of 5.5 km2.  The northern tributary near Point A is also still calving and retreating.

This embayment opens up new areas for Gentoo Penguins and Elephant Seals to occupy. There are current colonies in Royal Bay and like at Moraine fjord, these two species are early colonizers of deglaciated terrain (see map below from BAS). In particular the beaches adjacent to the northern tributary, just north of Point B and northwest of Point A are wave protected and low slope.  Levy et al (2016) discuss that the southern Gentoo Penguins tend to remain within the same archipelago year around. They examined DNA from 39 Gentoo at Bird Island, adjacent to South Georgia, and found none were migrants.

Hindle Fjord in 2020 and 2021 Sentinel images indicating ongoing retreat at Point A and C, with a significant sediment plume from Point B in December 2020. Point A is the northern tributary, Point B the middle tributary, Point C separates the eastern and western tributary and Point D is Ross Glacier.

Hindle Glacier comparison in 2001, 2017 and 2019 Landsat images.  The red arrow is the 2001 glacier terminus. Point A is the northern tributary, Point B the middle tributary, Point C separates the eastern and western tributary and Point D is Ross Glacier.

British Anatarctic Survey map of Royal Bay area showing Elephant Seal beaches (yellow X) and Gentoo Penguin colonies (purple dots).


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