Photo Friday: The Drygalski Ice Tongue

Ice tongues are the oddballs of the cryosphere. Extending roughly 70 kilometers (43 miles) into the sea, the Drygalski Ice Tongue, located in Antarctica’s McMurdo Sound, is the planet’s largest such feature. The National Snow and Ice Data Center define an ice tongue (sometimes called a glacial tongue) as an extension of a glacier or ice stream projecting seaward, usually afloat. Functionally, Drygalski is the floating end of the David Glacier, which reaches the sea from a valley in the Prince Albert Mountains of Victoria Land. Ranging from 14-24 kilometers (nine to 15 miles) wide, it is relatively narrow compared to its length, which distinguishes it from ice shelves and other floating ice masses.

The phallic shape sticks out like a sore thumb in a satellite image––or like a drying, cracking schmear of spackling. It is a perplexing ephemera whose very existence is under constant threat by belligerent icebergs released from the nearby Ross Ice Shelf. The massive icebergs roam the ocean freely, crashing into more fragile things, like ice tongues, and breaking them.

Drygalski Ice Tongue, Scott Coast, McMurdo Sound, Antarctica – February 6th, 2020 image is about 181 kilometers wide (Image: Pierre Markuse)

It’s easy to root for Drygalski’s survival, especially given the warming circumstances. Scientists estimate the ice tongue has been around for some 4,000 years, though one can imagine the number icebergs facing Drygalski with tongue-breaking potential has never been higher. In 2005 and 2006, Drygalski was struck by icebergs from the Ross Ice Shelf, which cleaved off two 27-square mile chunks in 2005 and one 39-square mile breakage in 2006.

The image (be sure to check out the high resolution image on Flickr) is a product of the Copernicus Sentinel 2 satellite, which was processed and shared by Pierre Markuse on Twitter. Markuse is based in Hamm, Germany and processes images taken from the European Space Agency’s Sentinel satellites and NASA’s Landsat orbiters. He was also responsible for the now-famous satellite image of the Camp Fire, which destroyed Paradise, California in November 2018.

The iceberg C-16 collides with Drygalski ice tongue on 30 March 2006 (Source: NASA/WikiCommons).

Large exposed ice tongues are a uniquely Antarctic phenomenon. As GlacierHub explained in a recent post, Antarctic glaciers flow outwards horizontally, and continue on into the water as huge floating shelves that stretch miles out to sea. Greenland glaciers flow down the island’s mountainous sides and break into icebergs when they hit the water. This behavior is common where a glacier’s terminus is close to where it starts to float—also known as the grounding line.

“Basically when [Greenland glaciers] start to go afloat, they form icebergs as opposed to Antarctica, where in most places they go afloat they don’t break off instantaneously but they form these big long ice shelves—floating extensions,” glaciologist Paul Winberry told GlacierHub. “It’s completely different.”

Looking right down the Drygalski Ice Tongue from the air (Image: Santiago de la Peña)

In response to Markuse’s sharing of the Drygalski satellite image, polar researcher Santiago de la Peña, who studies ice sheet dynamics and surface mass balance in Greenland and Antarctica at the Ohio State University’s Byrd Polar and Climate Research Center, replied with the head-on image of Drygalski featured above. He added the question, “I wonder what conditions favor the formation of such a tongue here?” The head of the Earth and Mission Science Division at the European Space Agency’s (ESA) Earth Observation program, Mark Drinkwater, replied. “Cold Ross Sea shelf waters, and no warm circumpolar deep water to destabilize it,” Drinkwater said.

For more earth observations, including cryosphere images, Markuse maintains a personal blog of the images he processes. You’ll want to bookmark it.

Editor’s note: After this article was published, ESA chief Mark Drinkwater tweeted the image below: “Here’s my all-time favorite Envisat image of Drygalski ice tongue and the most spectacular Ross Sea iceberg flotilla I’ve ever reported on.” The photo features an armada of icebergs, the largest of which is the aforementioned aircraft carrier-shaped berg named B-15A, which impacted the ice tongue, shattering the tip. Iceberg B-15A measured around 295 kilometers (183 mi) long and 37 kilometers (23 mi) wide, with a surface area of 11,000 square kilometers (4,200 square miles). It holds the record for the largest iceberg in the world––bigger than the country of Jamaica––so large it even has it’s own Wikipedia page. Also wandering the Ross Sea at the time were icebergs B-15K, C-16, and B-15J.

Read More on GlacierHub:

Thwaites Glacier in Antarctica is Now Causing Earthquakes

Photo Friday: “Antarctica” – An Exhibit Showcasing Lamont Scientists’ Photos from the Field

Video of the Week: “Return to Natural––Documenting the Tasman Glacier”

Roundup: Glacier-Fed Lakes, Remote Sensing, and Glacial Succession

Roundup: Glacier-Fed Lakes, Remote Sensing, and Soil


Global Warming and Glacier-Fed Lakes

From Freshwater Biology: “Climate warming is accelerating the retreat of glaciers, and recently, many ‘new’ glacial turbid lakes have been created. In the course of time, the loss of the hydrological connectivity to a glacier causes, however, changes in their water turbidity (cloudiness) and turns these ecosystems into clear ones. To understand potential differences in the food-web structure between glacier-fed turbid and clear alpine lakes, we sampled ciliates (single-celled animals bearing ciliates), phyto-, bacterio- and zooplankton in one clear and one glacial turbid alpine lake, and measured key physicochemical parameters. In particular, we focused on the ciliate community and the potential drivers for their abundance distribution.”

Learn more about how global warming affects lakes here:

A glacier-fed lake (Source: Rodrigo Soldon/Creative Commons).


Glacier Remote Sensing Using Sentinel-2

From Remote Sensing: “Mapping of glacier extents from automated classification of optical satellite images has become a major application of the freely available images from Landsat. A widely applied method is based on segmented ratio images from a red and shortwave infrared band. With the now available data from Sentinel-2 (S2) and Landsat 8 (L8) there is high potential to further extend the existing time series (starting with Landsat 4/5 in 1982) and to considerably improve over previous capabilities, thanks to increased spatial resolution and dynamic range, a wider swath width and more frequent coverage.”

Read more about remote sensing here:

Test region 1 in the Kunlun Mountains in northern Tibet using a S2A image from 18 November 2015 (Source: Remote Sensing).
Test region 1 in Tibet using a S2A image from 2015 (Source: Remote Sensing).


The Impact of Soil During Glacial Succession

From Journal of Ecology: “Plant–soil interactions are temporally dynamic in ways that are important for the development of plant communities. Yet, during primary succession [colonization of plant life in a deglaciated landscape], the degree to which changing soil characteristics (e.g. increasing nutrient availabilities) and developing communities of soil biota influence plant growth and species turnover is not well understood. We conducted a two-phase glasshouse experiment with two native plant species and soils collected from three ages (early, mid- and late succession) of an actively developing glacial chronosequence ranging from approximately 5 to <100 years in age.”

Learn more about the impact of soil during glacier succession here:

A photo of Lyman Glacier with different plants growing on its face (Source: Marshmallow/ Creative Commons).