Iceberg Melt Rates and Glacier Frontal Ablation: Seller and Heim Glacier, Antarctica

This post originally appeared on the AGU blog From a Glacier’s Perspective and was written by Mariama Dryak.

Figure 1: Study sites considered in this article: Seller Glacier and Heim Glacier. Landsat-8 image courtesy of the U.S. Geological Survey

Iceberg melt is caused by the temperature of the water in which an iceberg floats and the velocity of the water flowing around the iceberg. As a result, iceberg melt is an excellent indicator for the ocean conditions in which an iceberg resides. Given the remote location of Antarctica, and the difficulty in taking direct oceanographic measurements immediately in front of glacier termini in Antarctica, icebergs near glacier fronts can act as a useful proxy for what the ocean conditions are in these areas, especially under changing climate.

Dryak and Enderlin (2020) compared remotely-sensed iceberg melt rates (2013 – 2019) from eight study sites along the Antarctic Peninsula (AP) to glacier frontal ablation rates (2014 – 2018) where they overlapped in time and found a significant positively correlated relationship between the two. In general, iceberg melt rates were found to be much lower on the eastern AP where ocean waters are characterized as very cool relative to the heterogeneous, but generally warmer, waters on the western AP–where iceberg melt rates were higher. When we take a closer look at the data and consider what this means in the context of a stratified water column, the iceberg melt rate magnitudes also make sense relative to one another and what is known of regional ocean conditions.

Here we take a look at the results from two of those study sites: Seller Glacier and Heim Glacier.

Seller Glacier is the southernmost study site considered in our study on the Antarctic Peninsula, and produces very large, sometimes tabular icebergs with relatively high mean melt rates. Figure 2 indicates the changes in the same iceberg at two points in time. These icebergs are larger than and different in style to all of the other study sites, with the Seller Glacier terminus also being the widest of all the glaciers considered in the study. Due to the large area of the icebergs produced, we know that the keel depths of these icebergs also extend deep into the water column (See Table 1, Dryak and Enderlin, 2020), contacting warm subsurface waters (and some contacting Circumpolar Deep Water (CDW)) as characterized by Moffat and Meredith (2018) in Figure 3 below. In the upper layers these icebergs also sit in the very cold Winter Water (WW) layer and expanded section of Antarctic Surface Water (AASW) prevalent in the Seller region.

Figure 2: An iceberg from Seller Glacier in 2014 and later in 2016. Mean submarine melt rates for the Seller Glacier icebergs from this time period were 6.54 cm/day. Imagery © [2019] DigitalGlobe, Inc.

Frontal ablation rates at Seller Glacier are higher than expected given iceberg melt rates at the other sites on the western Antarctic Peninsula (Figure 4). Dryak and Enderlin (2020) suggest this to be because of a long-term dynamic adjustment of the Seller Glacier in response to the collapse of the Wordie Ice Shelf, which occurred between 1966 and 1989 (Vaughan, 1991)-a similar case to the sustained elevated velocities witnessed at Crane Glacier on the eastern Antarctic Peninsula following the collapse of the Larsen B Ice Shelf in 2002.

In contrast, the study site at Heim Glacier, north of Seller Glacier, contains smaller, shallow icebergs with low iceberg melt rates on par with iceberg melt rates found on the eastern Antarctic Peninsula. The glacier that produced the sampled icebergs, though not the smallest of the sites sampled, produces icebergs small in area that often do not last from one season to the next. The keel depths of the sampled icebergs at Heim Glacier likely do not reach below the cold WW layer (Table 1, Dryak and Enderlin, 2020), terminating in the very cold water layer or above in the compressed and comparatively cool AASW. However, the Heim study site is also located near the Marguerite Trough, an area of deep bathymetry known for the presence of warm waters, so the low melt rates here may be surprising to some without taking a closer look at the specific locale. Our study suggests that the bathymetry of the area in which the icebergs reside might be sheltered due to the presence of Blaiklock and Pourquoi Pas Islands, which may deflect warmer waters from reaching the Heim Glacier.

Figure 4:  Scatterplot of iceberg melt rates and frontal ablation for nearby glaciers over near-coincident time periods. Symbols indicate median frontal ablation rates. Figure 8 from Dryak and Enderlin (2020)

Frontal ablation rates at Heim Glacier are low, and of a similar magnitude to eastern Antarctic Peninsula sites, corresponding in magnitude to the low iceberg melt rates for the site as well (Dryak and Enderlin, 2020; Figure 8).

Overall, this paper re-emphasizes the importance of considering the ocean’s role in forcing changes on glaciers that terminate in the ocean around Antarctica, especially under changing climate. With the ocean acting as a large sink for excess heat in the atmosphere, evaluating the consequences of the storage of this heat in the ocean is essential when attempting to understand the feedback mechanisms associated with such change. The moral of the story is that we must keep one eye on the ocean going forward and how it could lead to changes in glacier dynamics, which could lead to changes in the contributions of glaciers to sea level and the marine ecosystems that exist within the ocean.

For full results and discussion of all of the study sites considered along the western and eastern sides of the Antarctic Peninsula, read the full Dryak and Enderlin (2020) article in the Journal of Glaciology.

*Note the Seller Glacier like many others in the region have experience rapid retreat in the last 30 years, Fleming Glacier, Sjogren Glacier and Boydell Glacier.

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Fogo Island’s Icebergs

This story was written for GlacierHub by Bonnie J. McCay, Ph.D, of Rutgers University. If you’d like to write a guest post for GlacierHub, contact us at glacierhub@gmail.com or @glacierhub on Twitter. 

My partner Roger Locandro and I like to come to our home on Fogo Island, Newfoundland, for a week or two in early March to enjoy a Newfoundland winter and particularly the vistas and dramas of “pack ice,” the local term for Arctic sea ice. This year, the COVID-19 pandemic led us to stay through April and possibly on to the summer, and so we have been able to witness the longer pattern of seasonality in the sub-Arctic NW Atlantic.

Figure 1. Arctic sea ice, Tilting, Fogo Island, April 17, 2020 (Photo: Bonnie McCay).

Here on the northeast coast of Newfoundland, what looks like spring on the standard calendar—April month––is better known as a time when Arctic sea ice dwindles and icebergs begin to show up. The northern coasts of Newfoundland and Labrador constitute the southern extent of Arctic sea ice, which begins to shrink in March and, in this region, disappears from coastal areas in April or thereabouts (National Snow & Ice Data Center, Arctic Sea Ice News & Analysis). Pack ice moves into and out of the harbors of Fogo Island with changes in tide and wind but can stay packed solid for long periods of time, stretching out to the horizon (Figure 1).

Figure 2. Iceberg off Joe Batt’s Arm, April 23, 2020 (Photo: Bonnie McCay).

The Arctic sea ice brings harp seals, who migrate southward in the spring, breeding and delivering pups at the edge of the ice off the coast of Newfoundland. For generations seal hunting was part of the annual cycle for Newfoundland fishers, and Fogo Island is close to “the front” of the harp seal fishery. This year the seal hunt has been called off because of the pandemic. Sometimes polar bears come this far south, too, following their prey. On April 5, 2020, a young polar bear was sighted close to our home in Tilting but, to our relief, was last seen at a nearby beach looking as if it was about to swim away.

Figure 3. Iceberg and boat off Fogo Head, Fogo Island, April 16, 2020 . Possibly the same iceberg as in Figure 2 (Photo: Bonnie McCay).

As the sea ice melts and retreats, icebergs are freer to move around and some arrive close enough to shore to be visible from land (Figure 2, 3). In recent years, Newfoundland tourist sky-rocketed based on the opportunity to see icebergs, which in some years are exceptionally numerous and large. We don’t know what this season will bring but so far, late April, we have seen half a dozen sizeable bergs, and in most years one can anticipate seeing icebergs well into June). Unfortunately, because of the pandemic they will not bring tourists.

Figure 4.  Iceberg off Joe Batt’s Arm, Fogo Island, April 15, 2020 (Photo: Bonnie McCay).

Some of the bergs we’ve seen so far this year look quite worn-out (Figure 4, 5), which is no surprise given the life history of the typical iceberg.

Figure 5.  Iceberg off Barr’d Islands, Fogo Island, April 23, 2020 (Photo: Bonnie McCay).

Those that make it to the waters of northeastern Newfoundland are probably from glaciers of the west coast of Greenland. They break off from glaciers such as Jakobshavn, where they form a dense river of pieces of ice that get swept north in the Baffin Bay current (Figure 6), and then drift southwards in the Labrador current, ending up in “Iceberg Alley,” which includes Fogo Island.

Figure 6.  Icefjord, Ilulissat, Greenland, August 18, 2015(Photo: Bonnie McCay).
Source: Canadian Ice Service

Their drift ends when they meet the warm waters of the Gulf Stream around the Grand Banks, some distance south of Fogo Island. It usually takes two or three years to make that trip, and so it’s no wonder that some of the icebergs look travel-worn when we see them.

Nevertheless, they are special and wondrous visitors (Figure 7), and we are happy to have the privilege of being here to see them.

Figure 7. Iceberg off Oliver’s Cove Head, Tilting, Fogo Island, April 17, 2020 (Photo: Bonnie McCay).

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Huge Cracks in Antarctic Glacier Foreshadow Epic Calving Event

The European Space Agency (ESA) released a video this past week showing the evolution of two very large and disconcerting cracks in Antarctica’s Pine Island Glacier. They have each grown to 20km in length and could shear off a hunk of ice the size of Paris and Manhattan combined.

The Pine Island Glacier—located at the base of the Antarctic Peninsula on the western side of the continent—has always shipped Antarctic ice out to sea at prolific levels, but it’s become famous in recent years due to its ever increasing output. These new cracks are just the latest development in a flurry of epic calving events at Pine Island. These used to occur about every six years but are now happening on an almost yearly basis.

The ESA compiled images of the cracks taken by one of their two polar orbiting Sentinel-1 satellites to make the video. Sentinel-1 is continuously monitoring land, sea, and sea ice conditions with a synthetic-aperture radar instrument that allows it to take pictures in all weather conditions and even at night—a key feature in high latitudes, which experience long periods of darkness in the winter months.  These satellites are part of ESA’s larger Copernicus mission.

Pine Island Glacier feeds into a floating body of ice called an ice shelf. A recent study published in Science Advances this month revealed that these ice shelves, and Pine Island Glacier  in particular, are experiencing accelerated melting from underneath, as a combination of fast moving and buoyant plumes of warm water carve troughs into their bottom surface. This makes the shelves more prone to large calving events and ultimately to shrinkage and retreat.

Pine Island Glacier is made of ice from the West Antarctic ice sheet and flows into the Amundsen Sea. (Credit: NASA)

“Warm water circulation is attacking the undersides of these ice shelves at their most vulnerable points,” said lead earth scientist and lead author of the report, Karen Alley. “These effects matter,” she added. “But exactly how much, we don’t yet know. We need to.”

The large calving event building at Pine Island Glacier also comes at a period of particular concern for melting glaciers around the world. The International Panel on Climate Change released its special report on the state of the Earth’s cryosphere last month in which it predicted continued warming of ocean waters and increasing mass loss of the Antarctic Ice Sheets—of which Pine Island Glacier is a part—throughout the 21st century.

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Photo Friday: The Power of Stories by the Global Oneness Project

Story telling can be a powerful tool in sharing unique human experiences between individuals. A good story is thought-provoking, captivating, and can have the power to influence and inspire people and their ideas.

The Global Oneness Project believes that stories play a very important role in education. This nonprofit provides lesson plans, images, films, and other educational resources for classrooms for free, with a goal to connect people through stories on issues such as climate change, food scarcity, and migration.

“Through featuring individuals and communities impacted by these issues, the stories and lessons provide opportunities to examine universal themes which include the following: identity, diversity, hope, resilience, imagination, adversity, empathy, love, and responsibility, and our common humanity.” they wrote on their About Us page.

Stories and lesson plans by the Global Oneness Project have been featured on numerous publications, including National Geographic, PBS, and TED Ed.

One of the project’s lesson plans is based on a photo essay by Camille Seaman, an award-winning photographer based in California.’Melting Away‘ features images of the rapidly melting icebergs in the polar regions of Svalbard, Greenland, Iceland, and Antarctica. In her essay, Seaman shares her personal experience of traveling across these regions, and witnessing the consequences of climate change.

Check out images from Seaman’s photo essay below.

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North Atlantic Icebergs: Hubris, Disaster, and Safeguards

The view out Diane Davis’ kitchen window on June 23, 2017 (Source: Diane Davis/Newfoundland Iceberg Reports).

2017 marked the fourth consecutive year of “extreme” iceberg conditions in the North Atlantic Ocean. According to the U.S. Coast Guard International Ice Patrol, 1,008 icebergs entered shipping lanes in 2017, almost twice the number in a normal season.

Funded by a treaty of 13 nations, the International Ice Patrol is operated by a U.S. Coast Guard unit, which conducts aerial surveys of the Grand Banks, a region southeast of Newfoundland prone to rough seas and a density of icebergs. Institutions from both the U.S. and Canada comprise the North American Ice Service, which creates a daily iceberg analysis for mariners. The patrol was founded following the sinking of the R.M.S. Titanic in 1912, and, except for the two World Wars, has been in continuous operation since 1913.

Icebergs are created when glaciers calve, releasing pieces of ice to the sea that can be as tall as skyscrapers. Most icebergs in the North Atlantic originate in Greenland, which is rimmed by glaciers that flow to the coast. According to the International Ice Patrol, the elevated count in 2017 was caused by severe storms and higher than normal calving rates of Greenland’s glaciers, which many scientists consider a response to climate change.

However, Mark Carey, an environmental historian at the University of Oregon, says it is overly simplistic to equate iceberg production and climate change, as even growing glaciers calve.

“The classic iconic representation of global climate change is a glacier calving into the ocean, creating icebergs,” he said. “When reports of high numbers of icebergs in the North Atlantic appear, like in the last few years, people might simply think that this is because glaciers in Greenland are shrinking fast and shedding ice.”

An iceberg and oil rig in Bay Bulls on May 1, 2017 (Source: Diane Davis/Newfoundland Iceberg Reports).

In fact, he says the journey an iceberg takes from a Greenland glacier to “Iceberg Alley,” a famously dense area of icebergs on the Grand Banks, is long and complex, and involves more than just glacial calving.

First, a newly-birthed iceberg may never actually leave the fjord in which it was formed. If it does reach the open ocean, it will follow the Labrador Current, which flows north up the west coast of Greenland and south along the east coast of Canada, for as long as two years. During this time, the iceberg may become trapped in sea ice or run aground in shallows. The vast majority of icebergs never reach Iceberg Alley, where the International Ice Patrol counts the icebergs that drift into shipping lanes below 48 degrees north latitude.

“Winter sea ice conditions also affect whether a berg survives and where it goes, so regional weather and not just global climate influence the iceberg journey,” Carey said.

Nevertheless, icebergs can have dangerous outcomes for ships traveling through the North Atlantic region, as the world saw during the sinking of the Titanic and the Danish ship Hans Hedtoft in 1959.

History and global politics makes the North Atlantic especially sensitive to the movements of icebergs. “The North Atlantic has been an integral part of the international political, economic and security system of the day for up to a millennium,” said Rasmus Bertlesen, professor of Northern Studies at the University of Tromsø.

“These shipping lanes are very important, since the U.S., the Canadian East Coast, and Western Europe are power houses of the world economy,” he added.

A life ring that washed ashore in Iceland was the only trace of the Hans Hedtoft recovered (Source: Rasmus Bertelsen).

No ship has collided with an iceberg in the region monitored since the M.S. Hans Hedtoft sank on its maiden voyage. To keep up with fast-moving ice, the Danish Meteorological Institute has recently launched a project that uses artificial intelligence to analyze ice distribution. Though Bertelsen agrees more frequent maps are necessary, he fears history will repeat itself.

“North Atlantic shipping has been the story of technological hubris, human disaster and then technological safeguards,” he said. “Hopefully, these artificial intelligence ice maps will not be the Titanic or Hans Hedtoft of our time leading to disaster and reckoning.”

Carey believes that the portrayal of icebergs as threats to shipping also adds allure to the subject, spurring tourism in places like Newfoundland and Alaska.

Diane Davis, a retired schoolteacher from Newfoundland who runs the Facebook page “Newfoundland Iceberg Reports” agreed.

“Icebergs are a huge tourist draw to Newfoundland and Labrador,” she said.

Davis created the Facebook page to facilitate iceberg sightings in the region. Currently, the page has 7,139 members, who monitor the photographs of icebergs and their locations.

Davis personally witnessed the higher density of icebergs in the North Atlantic over the last four years, and added that many of the icebergs drifted near coastal communities, where people were able to photograph them. The shipping industry is well-practiced at dealing with these icebergs, she said. More concerning to her is the interaction between icebergs and the offshore oil industry.

Diane Davis inspired a character in the Broadway musical “Come from Away,” and met Prime Minister Trudeau when the show toured in Newfoundland (Source: Justin Trudeau/Flickr).

Carey concurs with Davis’ concern. “Icebergs only pose a risk when people get close to the bergs, or when an iceberg drifts close to human populations, infrastructure like docks or drilling platforms, or boats,” he said.

In March 2017, for example, Husky Energy’s SeaRose floating platform came within 463 meters of a large iceberg, threatening 84 crew members and 340,000 barrels of crude oil aboard. The board that monitors industry in the oilfields off Labrador suspended operations for SeaRose, the first such suspension in over a decade.

“Iceberg risk is not just about iceberg production or numbers of bergs in the shipping lanes,” Carey said. “It is also influenced by how often and how many people live, work, travel, and vacation near icebergs–and these numbers are on the rise all the time.”

Photo Friday: Capturing Climate Change Through Art

“It is my life’s mission to convey the urgency of climate change through art,” states Zaria Forman. And she does this through painstakingly drawn, detailed pastel drawings that look so real they can often be mistaken for photographs.

She captures the beauty of places like Hawaii, the Maldives, Greenland, and Antarctica.

Her series of pastel drawings, Antarctica, in particular, captures landscapes in flux. “As temperatures rise, glaciers melt more rapidly than they grow. Many of us are intellectually aware that climate change is our greatest global challenge, and yet the problem may feel abstract, the imperiled landscapes remote. The scale and detail of my drawings are meant to make Antarctica’s magnificence and ephemerality visceral to the viewer, emulating the overpowering experience of being beside a glacier,” says Zaria.

A reproduction of her work Whale Bay, Antarctica, No.4, 84×144, 2016, and a time-lapse video depicting the process of making the work, is currently being featured as part of the first exhibition, In Human Time, for the Climate Museum in New York. It is presented in partnership with the Parsons School of Design’s Sheila Johnson Design Center at The Arnold and Sheila Aronson Galleries on Fifth Avenue and will be exhibited till January 15.

For more information on Zaria Forman, visit zariaforman.com.

For more information on the exhibition and the Climate Museum, visit climatemuseum.org.

 

Whale Bay, Antarctica no.4, 84×144, 2016 (Source: Zaria Forman).

Whale Bay is a place on the western side of the Antarctic peninsula where icebergs calved from a nearby glacier are carried by wind and water to their final resting place. The icebergs scrape against the shallow bay becoming “grounded” (they remain there until they have completely melted). As the bay encloses grounded icebergs, it is also called an “iceberg graveyard.”

Whale Bay, Antarctica no.1, 60×90, 2016 (Source: Zaria Forman).

 

Whale Bay, Antarctica no.2, 50×75, 2016 (Source: Zaria Forman).

 

 

 

 

 

 

 

Photo Friday: Icebergs at Berg Lake

Located in Mount Robson Provincial Park in British Columbia, Canada, Berg Lake tends to be filled with icebergs throughout the year. Visitors often see ice break off or calve into the lake, which is partially fed by Berg Glacier. Known for its glacier, floating icebergs, and bright bluish-green water, the lake is a popular destination for hikers. Berg Glacier sits atop Mount Robson, the tallest peak in the Canadian Rocky Mountains. Mount Robson is part of a sub-range of the Rocky Mountains known as the Rainbow Range. Named “Tsitsutl,” meaning “painted mountains” in the local dialect, Rainbow Range is made of lava and rock that comes in hues of red, orange, lavender and yellow, noticeable on sunny days.

Mount Robson Provincial Park, including Berg Lake and Glacier, was designated a UNESCO world heritage site in 1990. For a visceral experience of the park, attend the 7th Annual Mount Robson Marathon to be held on September 9, 2017. The marathon will take runners up the world-renowned Berg Lake Trail. Below, you can find a video of hiker Phil Armitage on the trail.

 

Icebergs floating in Berg Lake (Source: Scott Theede/Flickr).

 

 

Berg Glacier at Mount Robson Provincial Park in British Columbia (Source: Jeff Pang/Flickr).

 

 

South face of Mount Robson (Source: Jeff Pang/Flickr).

 

 

Overlander Falls in Mount Robson Provincial Park (Source: Guenter Wieschendahl/Creative Commons).

 

 

Photo Friday: Seals taking it easy on icebergs

Seals are some of the cutest animals found in the Arctic and the Antarctic. This week’s photo friday features seals carrying out their daily activities on icebergs, which are important environmental features in their chilly habitats. The photos include leopard seals and crabeater seals among other species.

Photo Friday highlights photo essays and collections from areas with glaciers. If you have photos you’d like to share, let us know in the comments, by Twitter @glacierhub or email us at glacierhub@gmail.com.