In this week’s Video of the Week, watch a massive glacier calving event that occurred at Helheim Glacier in Greenland. The video was captured on 22 June 2018 by Denise Holland of New York University.
The calving event took place over a 30-minute time period, and was sped up into a time-lapse of about 90 seconds. During this time span, over four miles of the glacier’s edge broke off, flowing into one of the fjords that connects Helheim Glacier to the ocean. To put this in perspective, a calving event of this size would measure roughly the size of lower Manhattan, all the way to Midtown in New York City. In a warming world, glacier calving is a large force contributing to global sea-level rise.
A recent paper published in the Journal of Glaciology explores how a team of researchers studied waves in a Patagonian lake to detect glacier calving events at Glaciar Perito Moreno. Calving events occur when an iceberg detaches from the glacier front. Such events produce waves of different magnitudes as the glacier discharges into the ocean or an adjacent lake.
The paper’s lead author, Masahiro Minowa, told GlacierHub that while calving plays a key role in the recent rapid retreat of glaciers around the world, many processes related to calving are still poorly understood because direct observations are scarce and challenging to obtain.
Minowa and his team employed a creative methodology to observe calving events at a distance. Employing four time-lapse cameras and a water pressure sensor, they conducted fieldwork in three separate time periods, roughly one week to three weeks long between 2013 and 2016. 420 events were noted within this relatively short period of time. They also estimated the calving volume using the time-lapse images and maximum wave amplitude.
“We did our field works twice in summer and once in winter so that we could observe the seasonality of calving activity. We also wanted to understand mechanisms driving calving if there are any,” Minowa said.
The researchers categorized the time-lapse images by separating calving events into four groups: 1) Topple, an ice tower toppling into the lake; 2) Drop, an ice block dropping into the water; 3) Serac, a small piece of serac slipping down to the lake; and 4) Subaqueous, an underwater iceberg detachment that floats up to the lake surface.
These images were then scrutinized in great detail. For example, Topple and Drop events were distinguished based on whether crevasse widening occurred; while Subaqueous was differentiated from other subaerial events by noting a relatively large single iceberg appearing without any geometrical change on the glacier front and a lack of sediment inclusion on the surface.
The surface wave profiles corresponding to the events were also examined. Their signals were more complex, making it difficult in some cases to distinguish events on the basis of wave profiles alone.
“Initially, we expected a clear difference in wave frequencies between subaqueous and subaerial events. While we could see some difference in frequencies, we are unsure if this is a result of different calving style,” Minowa explained. Wave frequencies also vary based on the relative location of the event to the sensor, even if it is the same calving style. A larger sample of cases is thus required to confirm the wave patterns associated with different calving events.
However, Minowa stressed the importance of choosing a strategic location for the water pressure sensor, which vastly affects the results and findings of a glacier calving study. He warned that a problem may arise from the instrument’s location. “Since waves’ amplitude decay with distance, you will not be able to detect all of the calving events if you place the sensors too far. So, you need to be close enough to the glacier, and you will easily detect many of them,” he said. Yet, this might limit the scope of the area studied, requiring a balanced consideration.
From the data, the team could see the seasonality of calving activity. Their results showed that calving events were 2.6 times more frequent during the austral Summer (December-March) as compared to Spring (October). Subaerial calving events occurred 98 percent of the time, although Minowa conceded that the dataset was a bit short to confirm any trigger mechanisms.
Following the research, the team is now ready to install new water sensors for a year-round measurement around the glacier in the hope of further understanding calving processes through the use of surface-waves in glacier fronts. This is a step toward reducing glacier melting in Patagonia and the rest of the world.
Roundup: Kayaks, Regrowing Glaciers, and the Bowdoin
Research Using Remote-Controlled Kayaks
From Alaska Public Media: “LeConte Glacier near Petersburg… [is] the southern-most tide water glacier in the northern hemisphere and scientists have been studying it to give them a better idea of glacial retreat and sea level rise around the world… to get close to the glacier, which is constantly calving, a team of scientists is relying on unmanned, remote controlled kayaks… these kayaks have been completely tweaked by Marion and an ocean robotics team from Oregon State University… The boats are customized with a keel, antennas, lights and boxes of computer chips and wires.”
Regrowing Morteratsch Glacier with Artificial Snow
From New Scientist: “The idea is to create artificial snow and blow it over the Morteratsch glacier in Switzerland each summer, hoping it will protect the ice and eventually cause the glacier to regrow… The locals had been inspired by stories that white fleece coverings on a smaller glacier called Diavolezzafirn had helped it to grow by up to 8 metres in 10 years… Oerlemans says it would take 4000 snow machines to do the job, producing snow by mixing air blasts with water, which cools down through expansion to create ice crystals. The hope is that the water can be “recycled” from small lakes of meltwater alongside the glacier… But the costs… are immense.”
From The Cryosphere: “A high-resolution displacement field is inferred from UAV orthoimages (geometrically corrected for uniform scale) taken immediately before and after the initiation of a large fracture, which induced a major calving event… Modelling results reveal (i) that the crack was more than half-thickness deep, filled with water and getting irreversibly deeper when it was captured by the UAV and (ii) that the crack initiated in an area of high horizontal shear caused by a local basal bump immediately behind the current calving front… Our study demonstrates that the combination of UAV photogrammetry and ice flow modelling is a promising tool to horizontally and vertically track the propagation of fractures responsible for large calving events.”
A calving event in Porcupine Glacier shows rapid retreat
From the American Geophysical Union: “Porcupine Glacier is a 20 km long outlet glacier of an icefield in the Hoodoo Mountains of Northern British Columbia that terminates in an expanding proglacial lake. During 2016 the glacier had a 1.2 square kilometer iceberg break off, leading to a retreat of 1.7 km in one year. This is an unusually large iceberg to calve off in a proglacial lake, the largest ever seen in British Columbia or Alaska… The retreat of this glacier is similar to a number of other glaciers in the area: Great Glacier, Chickamin Glacier, South Sawyer Glacier and Bromley Glacier. The retreat is driven by an increase in snowline/equilibrium line elevations which in 2016 is at 1700 m, similar to that on South Sawyer Glacier in 2016.”
Learn more about the retreat of Porcupine glacier, and view satellite images here.
Patterned ground exposed by glacier retreat in the Alps
From the Biology and Fertility of Soils: “Patterned ground (PG) is one of the most evident expressions of cryogenic processes affecting periglacial soils, where macroscopic, repeated variations in soil morphology seem to be associated with small-scale edaphic [impacted by soil] and vegetation gradients, potentially influencing also microbial communities. While for high-latitude environments only few studies on PG microbiology are available, the alpine context, where PG features are rarer, is almost unexplored under this point of view… These first results support the hypothesis that microbial ecology in alpine, periglacial ecosystems is driven by a complex series of environmental factors, such as lithology [study of the general physical characteristics of rocks], altitude, and cryogenic activity, acting simultaneously on community shaping both in terms of diversity and abundance.”
Learn more about glacier retreat in the Italian Alps here.
Microorganisms found in glacial meltwater streams
From Polar Biology: “Microbial communities living in microbial mats are known to constitute early indicators of ecosystem disturbance, but little is known about their response to environmental factors in the Antarctic. This paper presents the first major study on ciliates [single-celled animals bearing cilia] from microbial mats in streams on King George Island (Antarctica)… Samples of microbial mats for ciliate analysis were collected from three streams fed by Ecology Glacier. The species richness, abundance, and biomass of ciliates differed significantly between the stations studied, with the lowest numbers in the middle course of the stream and the highest numbers in the microhabitats closest to the glacier and at the site where the stream empties into the pond. Variables that significantly explained the variance in ciliate communities in the transects investigated were total organic carbon, total nitrogen, temperature, dissolved oxygen, and conductivity.”
“In the polar regions cyanobacteria are an important element of plant communities and represent the dominant group of primary producers. They commonly form thick highly diverse biological soil crusts that provide microhabitats for other organisms. Cyanobacteria are also producers of toxic secondary metabolites. The north-west coast of Spitsbergen, are able to synthesize toxins, especially microcystins and anatoxin-a. To the best of our knowledge, this is the first report on the presence of ANTX-a in the entire polar region. The occurrence of cyanotoxins can exert a long-term impact on organisms co-existing in biocrust communities and can have far-reaching consequences for the entire polar ecosystem.”
“During summer 2013 we installed a network of nineteen GPS nodes at the ungrounded margin of Helheim Glacier in south-east Greenland together with three cameras to study iceberg calving mechanisms… The glacier calved by a process of buoyancy-force-induced crevassing in which the ice downglacier of flexion zones rotates upwards because it is out of buoyant equilibrium. Calving then occurs back to the flexion zone… “
“It is presented the results of study of bottom sediments of the proglacial lakes enriched with meltwater of Peretolchin Glacier, Chersky Glacier and glaciers of the Kodar Ridge. Bottom sediments were investigated with time resolution in year-season, using X-ray fluorescence. We have defined three periods in significant increase of glacier flow/melting during the last 210 years. The first period (ca. 1800–1890), supply of suspended material by meltwater into Lake Ekhoy and Lake Preobrazhenskoe, was not intense until 1850 and 1875, respectively. However, the rate of meltwater supply into Lake Izumrudnoe was high during the Little Ice Age, and it is likely attributed to local moisture from Lake Baikal. The regional glacier water balances were most likely positive during the second period (ca. 1890–1940). The third period (ca. 1940–till present) was characterised by moderate melting rate of glaciers located on the Kodar and Baikalsky Ridges, in contrast to Peretolchin Glacier that demonstrated the highest rate of melting and changes in outlines during this period.”
A wall of ice from Childs Glacier in Alaska crumbles into the Copper River, gradually at first and then all at once. As a massive wave created by the calving glacier builds power, two tiny figures appear against the vast gray expanse of churning water, one on a surfboard and the other on a jet ski. This is glacier surfing and just watching it might give you the chills.
Back in 2007, surfers Kealii Mamala and Garrett McNamara, a professional big wave rider who set a world record for surfing the largest wave ever, wanted to become the first people to surf a glacier. They made a video to show off their attempt.
The video is hard not to watch. As the wave speeds towards the two men, it looks as though the water washes right over them. “Oh, is he in there? Is he going to come out?” says an unidentified videographer as he loses sight of the figure on the surfboard.
The jetski circles back behind the wave. It’s a good 25 seconds before the little figures reappear, and the camera-man and spectators on the shore become the first to witness a human being surfing a wave created by the power of a glacier falling into the sea.
If you were to list the dangers of surfing next to a collapsing sheet of ice, one of the top ones might be getting hit by any of the enormous chunks of jagged ice that are launched into the air when the glacier hits the water.
“It’s like a bomb, and the giant pieces of ice fly like shrapnel,” McNamara said in “The Glacier Project,” a documentary about riding the ice wave.
It turns out that Copper River at Child’s Glacier is an ideal location for surfing. When a piece of ice calves from the glacier, it displaces enough water to make a wave so large that it curls all the way across the width of the river in a single sweep. This means there are no competing “break points.” According to Surfline.com, a website devoted to identifying the best surfing spots using weather reports and scientific measurements, a wave where all the break points line up is a “perfect” wave, because then a surfer can ride the wave all the way from one end to the other.
The seeds of the Glacier Project were first sown back in 1995, when filmmaker Ryan Casey worked on an IMAX filmAlaska: Spirit of the Wild with his father George Casey, near Childs Glacier. During the filming, Casey saw bits of ice break off from the glacier and fall into the water below, creating the kind of giant uniform wave described above. Casey thought it would be perfect for surfing, if only surfers could get out there. The practice of jet ski towing, by which a surfer is towed into a breaking wave, was not common at the time, but it was 12 years later, when Casey, McNamara, and Mamala headed to Alaska to test Casey’s theory that these glacier waves could be surfed.
“After the scout, I guaranteed that we would ride a wave – any wave,” McNamara said in an interview with surfingmagazine.com. But his enthusiasm evaporated pretty quickly. “After the first day, I just wanted to make it home alive. Not knowing where the glacier was going to fall, where the wave would emerge, or how big it would be. It was so different to anything we’ve experienced in our big-wave tow-surfing history. I spent most the time thinking about my family and wondering if I would survive to see them again. It was in a realm all its own.”
McNamara and Mamala each rode glacier waves during the trip. The largest for McNamara was 15 feet, while Mamala managed to snag a 20-25 foot wave, according to a press release about the project.
“I wouldn’t recommend it for any one,” McNamara said after his trip to Childs Glacier. “I won’t be going back. This is not a new sport.” So far, history has proved him right. The 2007 trip may constitute the only attempt at glacier surfing that will ever be made. There is little evidence that anyone has attempted a similar ride in the seven years since.
On July 20, 2010, researchers from Swansea University in Wales were setting up equipment near Helheim Glacier in Greenland when they happened to witness a 4-kilometer crack in the ice forming that extended from one side to the other. Quickly, they set up a time-lapse camera to record one of the largest glacier calving events ever filmed. They knew that they glacier advanced rapidly, achieving speeds as high as 30 meters per day, but they had not expected a sudden event.
As the split in the ice grew, it thrust the front part of the glacier into the ocean with great force. It rotated and flipped over into the ocean in the seconds before the glacier front fully broke off and floated away. Once the separation was complete, the ocean was filled so thickly with chunks of ice it was impossible to see the water.
This film and other data form the basis of a new study that was published last month in the journal Nature Geoscience, “Buoyant flexure and basal crevassing in dynamic mass loss at Helheim Glacier.” The researchers, Timothy D. James, Tavi Murray, Nick Selmes, Kilian Scharrer and Martin O’Leary, found the ocean itself is breaking up the glaciers. In plainer English, when a glacier reaches the sea, the front will float, bending the ice and creating crevasses at the bottom, causing the front of the glacier to snap off. These crevasses are much harder to detect that the ones on the surface, so their role had not previously been understood. The bending of the surface was a second discovery. The team used a stereo camera to record subtle elevation changes over two summers, capturing details that previous cruder calving studies had missed.
Scientists had long known that when a glacier calves, it breaks off into the ocean. They knew as well that this ice leads to sea level rise, a seemingly straightforward process. And now they have a fuller understanding of the hows and whys of glacier calving. This knowledge is important, because most of the Greenland’s glacial ice loss over the next 200 years is expected to be from such breaking off of ice into the ocean. Armed with a clearer grasp of the calving process, researchers will be better able to produce better models of ice dynamics and sea level rise—of importance to the billions who live in coastal areas, far from Helheim but intimately connected to it.