The GlacierHub News Report is a bi-monthly video news report that features some of our website’s top stories. This week, GlacierHub news is covering glacier flow, glacier calving, and the environmental monitoring of Svalbard and Jan Mayen.
This week’s news report features:
Observing Glacier Calving through Time-Lapse Imagery and Surface Water Waves
By: Sabrina Ho Yen Yin
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.
Summary: A new analysis published in the Journal of Science argues that the “largest uncertainty” in ice sheet models used to predict future sea-level rise originates from our limited understanding of underwater processes at the ice-bed interface.
The Environmental Monitoring of Svalbard and Jan Mayen
By: Sabrina Ho Yen Yin
Summary: The Environmental Monitoring of Svalbard and Jan Mayen (MOSJ) is an umbrella program that collects and analyzes environmental data in the arctic regions of Svalbard and Jan Mayen. Some data of interest include the extent and thickness of sea ice around Svalbard, Fram Strait and the Barents Sea; temperature and salinity of the water transported around Svalbard via the West Spitsbergen Current; ocean acidification; and local sea level changes.
The Pine Island Glacier (PIG) is losing ice rapidly. During the past 25 years, the ice of the PIG and its neighboring glaciers in west Antarctica’s Pine Island Bay thinned between 3.9 and 5.3 meters a year, accounting for about 5 to 10 percent of observed global mean sea-level rise. Before 2015, however, the front of the PIG had been at a relative standstill since the 1940s, not retreating as one might expect of a melting glacier. Why? To account for this unique situation, a recently published study in The Cryosphere points to ridges below the ice that likely held the PIG’s ice front in place despite its rapid melting.
In August 2015, the long steady front of the PIG changed significantly when large sections of ice broke off during a calving event when the glacier retreated upstream and its orientation shifted. This change presented an exciting opportunity in 2017 for researchers from the Alfred Wagner Institute for Polar and Marine Research to map the seafloor formerly covered by the PIG.
To complete this mapping project, the researchers employed an echo sounder mounted to the hull of the research vessel RV Polarstern, in addition to complementing remote sensing data acquired by satellite. The information acquired by the expedition through echo sounding showed the seafloor features that were present below the PIG. With this data in hand, the researchers had the idea to correlate this information with satellite data from the past to the present to better understand the role of these features for the calving behavior of PIG, according to lead author Jan Erik Arndt, who spoke with GlacierHub about the study.
These survey methods revealed a complex, underwater landscape once covered by the PIG. The discoveries included a 10-kilometer long ridge and two other high points. At its deepest point, Pine Island Bay reaches down over 1,000 meters, while the submarine ridge peaked at 375 meters below the ocean’s surface and the two downstream high points peaked at 350 and 250 meters below the surface
How did these sub-surface features impact the PIG? Satellite data from January 1973 until March 2005 showed a rumple in the PIG’s ice above the location of shallowest section of the underlying ridge. A glacial rumple is similar to a bump on a beach towel that suggests there is a beach toy or pile of sand below it. In the case of the PIG, the ridge below the ice acts as an obstacle in the the way of the ice, leading to a raised section of the glacier directly above the point of contact between it and the ridge. This rumple is not observed after March 2005 in the satellite data, indicating that the ice after this date had thinned to such a degree that it either was no longer in contact with the ridge or was too light to produce a signature on the surface.
The loss of contact with the ridge was consequential. In the time before this separation when the PIG was in contact with the underwater ridge, the ridge acted as a “pinning point,” holding it in place. However, after the ice had thinned considerably, the ridge no longer acted as a restraint on the PIG. As a result, in the time since there was evident contact between the two, four major calving events occurred.
The first of these events took place in 2007 when the PIG advanced and made contact with one of the subsurface downstream high points (A in figure 3). This impact placed what is known as “back stress” on the glacier upstream from the point of contact, causing rifts to form in the ice and ultimately leading to the calving event.
The process leading to the 2011 calving event was similar, the researchers state. In this instance, the second subsurface high point (B in figure 3) trapped a dense cluster of icebergs between it and the PIG ice shelf, placing back stress on the upstream ice leading to the calving event.
The 2015 event was different: The ice-flow velocity of the northern edge of the PIG’s ice shelf was nearly at a stand still, whereas the velocity of the ice shelf’s central and southern edges increased. Further, the direction of the northern edge’s ice flow shifted around 3 degrees clockwise, while the direction of the central and southern edges did not change (C in Figure 3). The reason? The northern edge of the ice-shelf was likely making slight contact with the submarine ridge, according to the authors.
As a result, the calving line that had not changed orientation in decades finally did change due to the loss of contact between the ice and its previous pinning points as well as from melting from below driven by warm ocean waters. The most recent calving event which occured in 2017 happened along the same orientation, which aligns with a new pinning point to the north near Evans Knoll, a small snow-covered hill that rises above sea level. The point near the knoll is likely one of the last anchors acting on the PIG, according to Arndt.
This new calving line and loss of contact with past pinning points could have grave implications for PIG. A 2017 study on the PIG and a number of other glaciers in the area found that changes to a glacier’s ice shelf propagate upstream within just a few years. For the PIG, this likely means the glacier’s flow will speed up and thinning will increase, leading to further melting.
It is unlikely the PIG’s calving line will retreat much further over the next few years thanks to the new pinning point stabilizing the glacier near Evans Knoll. However, the authors note that there is continued thinning due to melting. This thinning has the potential to destabilize the glacier and unfortunately may have already started, according to Arndt. The large icebergs produced by the recent calving events have broken up into smaller icebergs much more quickly due to the thinner ice than events in the past, when they remained stable for longer. This ongoing breakup and subsequent melting of calved icebergs will contribute to already rising global sea-levels, threatening the millions of people who live along the coast. And unlike the ridges that held the front of the PIG for decades, many coastal communities will not have anything to hold back the sea.
Each week, we highlight three stories from the forefront of glacier news.
Climate Change Education for Mendenhall Glacier Tourists
From KTOO: “On a busy summer day, thousands of people — mostly cruise ship passengers — visit Juneau’s Mendenhall Glacier. The U.S. Forest Service wants those tourists to take in the dramatic views, but also consider why the glacier is shrinking. Visitor center director John Neary is making it his personal mission. That means trying to make the message stick — long after the tourists are gone…“It became our central topic really just in the last few years,” said Neary. He’s not afraid to admit he’s on a mission. He wants the more than 500,000 people who visit the glacier each year to know that it’s rapidly retreating due to climate change, and the 18 interpreters who work for him are prepared to talk about it.”
Pemberton Icefield Glacier Breaks the Fall of a Crash-Landing in Canada
From Weather.com: “‘We tried to accelerate — that was the end of the valley, like cul de sac.’ Jedynakiewicz. told the CBC . ‘I say, ‘Full power! Full power!’ But the plane doesn’t respond. I checked in the last second, the speed it was 40 miles [per hour] when [we made] impact with the ice. It was a soft landing, soft like on a pillow. Believe me.’ The impact knocked out the plane’s radio, Toronto Metro reports, but left the plane almost undamaged and the three men unhurt. ‘I think the wing tips only missed the rock pile by about a foot,’ Hannah told the Metro. There was rocks on one side and a waterfall right in front of us and we jumped over the waterfall (to reach the glacier). So it was touch and go all right. It was a miracle. First thing was say, ‘Oh, God thank you we are alive,’” Jedynakiewicz told the CBC. ‘Not even scratch can you imagine? Three of us.’”
From Albany Daily Star: “A glacier in northeast Greenland that holds enough water to raise global sea levels by more than 18 inches has come unmoored from a stabilizing sill and is crumbling into the North Atlantic Ocean. Losing mass at a rate of 5 billion tons per year, glacier Zachariae Isstrom entered a phase of accelerated retreat in 2012, according to findings published in the current issue of Science. “North Greenland glaciers are changing rapidly,” said lead author Jeremie Mouginot, an associate project scientist in the Department of Earth System Science at the University of California, Irvine. “The shape and dynamics of Zachariae Isstrom have changed dramatically over the last few years. The glacier is now breaking up and calving high volumes of icebergs into the ocean, which will result in rising sea levels for decades to come.” The research team – including scientists from NASA’s Jet Propulsion Laboratory and the University of Kansas – used data from aerial surveys conducted by NASA’s Operation IceBridge and satellite-based observations acquired by multiple international space agencies (NASA, ESA, CSA, DLR, JAXA and ASI) coordinated by the Polar Space Task Group.”
Listening to the unique creaks and cracks of an arctic fjord, six researchers affiliated with the Polish Academy of Sciences recorded the sounds glaciers make as they break off into water. The recordings are being used in an important effort to better understand this process of breaking off, called calving.
Glacial calving is “poorly understood” according to the researchers who published a new article in the scientific journal, Geophysical Research Letters, titled, Underwater acoustic signatures of glacier calving. However, through their research they successfully identified three distinct ways that glaciers calve, typical subaerial, sliding subaerial, and submarine. Basically, whether the piece of ice breaking off was falling outward from the top of the glacier, like a person jumping off the top, sliding straight down the face of the glacier, like something very slowly sliding off the top, or was actually breaking off underwater and shooting up to the surface, like a person swimming back up after falling in.
Although glaciers around the world, by definition, are all large masses of ice that last year-round and slowly move, they vary in size, shape, speed, and importantly, location. Eventually, many glaciers terminate at bodies of water. Glaciers that terminate at bodies of water with tidal patterns, like oceans fjords, and sounds, are called tidewater glaciers. Tidewater glaciers are a form of calving glaciers, which break off into chunks as they push forward into bodies of water, creating icebergs.
This new article adds to our understanding of this process in a novel way. By recording the sounds of the calving process the researches overcame previous obstacles in monitoring these events. In the past, keeping track of tidewater glacial calving was difficult due to the lack of sunlight in the poles and the poor quality of satellite imagery. However, using relatively cheap and simple underwater microphones, called hydrophones, attached to a buoy, the researches identified the distinct sound signatures of the ice slowly melting, cracking and expanding, and eventually, breaking off from the glacier altogether. The researchers then combined the calving sound signatures with photographs from a GoPro camera they had set up to monitor the events visually, allowing them to identify and confirm the three distinct types of calving.
They say that by continuing to monitor the underwater sounds glaciers make, scientists will be able collect more data on how, and how much, glaciers around the world are breaking off into the bodies of water in which they terminate. This will help to better understand the calving process itself, as well as allow them to keep better track of how quickly glaciers are melting due to climate change.
This is important, because tidewater glaciers contribute more water to global sea level rise than any other type of glacier, and by some counts, contribute more water to sea level rise than the Antarctic and Greenland Ice Sheets combined.
By establishing the connection between the visual and audio information the researches established that these sound signatures did in fact correspond to these particular types of events, and presumably, could be used on its own in the future– giving scientist a cheap and easy monitoring tool to gauge glacier calving around the world.
“Iceberg calving is ultimately related to the mechanical failure of ice. However, predicting mass loss from calving events remains challenging because calving takes on diferent forms under different conditions. For example, large tabular icebergs sporadically detach from freely foating ice tongues with many years of quiescence between major calving events”
Read more on ESRI’s Story Maps and Time-lapse here.
Linking Earth’s Ice Ages to Ocean Floor topography
“The evidence comes from seafloor spreading centers: sites throughout the ocean where plates of ocean crust move apart and magma erupts in between, building new crust onto the plates’ trailing edges. Parallel to these spreading centers are “abyssal hills”: long, 100-meter-high ridges on the diverging plates, separated by valleys. On bathymetric maps of seafloor topography, they look like grooves on a record. These grooves, it now turns out, play the tune of Earth’s ice ages.”
“As glaciers increasingly melt in the wake of climate change, it is not only the landscape that is affected. Thawing glaciers also release many industrial pollutants stored in the ice into the environment. Now, within the scope of a Swiss National Science Foundation project, researchers from the Paul Scherrer Institute (PSI), Empa, ETH Zurich and the University of Berne have measured the concentrations of a class of these pollutants – polychlorinated biphenyls (PCB) – in the ice of an Alpine glacier accurately for the first time.”
Iceberg Calving is Extremely Sensitive to Climate Change
“Sea level rise is among the greatest threats due to climate change. Over the next century, ice sheets and glaciers will be one of the main contributors, through melting and calving of ice into the oceans. The amount of calved ice is not easy to reproduce in computer simulations, and due to the rapid and non-linear variability of calving fluxes, they are usually difficult to include in models forced by evolving climatic variables. Simulation of iceberg calving remains one of the grand challenges in preparing for future climate change.”
“I started from a data analysis conducted by the Swiss Glacier Monitoring Network to see the map of the glacier and its relative changement in the length variation from 1961 and 2011. It’s interesting the word used to call the part of a glacier that goes under a certain mass. They are called “dead”. All the pictures shown here are taken to the new entrance of the glacier, in the “dead” part of it. Looking at the map, 50 years ago, this would have been completely covered by the ice.”
Have you ever wondered how glaciers melt? Do they melt from underneath? Top down? Maybe from all around at once? From the center outward? How fast do they melt? Do all glaciers melt? These are questions scientists’ wonder too, and they’ve been getting some interesting answers.
Virtually every glacier on earth melts each year during the summer, but as long as winter snow accumulation is equal to or greater than that summer melt, a glacier is considered to be stable or growing. If the glacier melts more in the summer than it grows in the winter however, it retreats. But exactly how glaciers melt has not been understood in a comprehensive manner. What is known is that glacial ablation can be caused by any number of natural forces: wind, sun, rain, fauna, evaporation, sublimation and every other possible fashion one could imagine removing a chunk of ice from a even larger chunk of ice.
One of the most talked about forms of glacial ablation is glacial calving. Icebergs, for instance, are created when a chunk of glacier breaks off (or calves), usually falling into the body of water to which it drains. Calving often occurs from a process of erosion at the water line. Calving has gotten attention lately because of new evidence showing that for some glaciers, warmer ocean temperatures have been inarguably increasing the rate of glacial erosion underneath the water line. “Researchers found that, for some ice shelves, melting on its underbelly could account for as much as 90 per cent of the mass loss,” according to research published in Nature in September of last year. This aspect of glacial melt that was not previously well understood, but calving and ocean erosion are not the whole story to glacial ablation.
In 2008, Natalie Kehrwald, a Ph.D. student at Ohio State University, was attempting to date ice cores she drilled from a glacier in Tibet twenty thousand feet above sea level by searching for particular radioactive isotopes found all over the world from the mid-20th Century U.S. and Soviet Union atomic testing. She soon realized she couldn’t find the isotopes she was looking for. Confused, she used a different technique to date the top-most layer of the ice cores, and discovered that the newest ice in the samples dated from the 1940s. Kehrwald inadvertently proved that glaciers at those elevations in the Himalayas melt from top to bottom. Of course, it was the first time anyone had observed such a phenomenon, and it doesn’t mean top-down is the only way mountain glaciers melt.
At the Sandy Glacier on Mount Hood in Oregon, two climbers have discovered another particularly fascinating way glaciers melt. Brent McGregor and Eddy Cartaya have been exploring a system of glacial caves that extend more than 7,000 feet inside the glacier. Beautifully sculpted on the inside and ready-made for adventure, these glacier caves are significant because they exhibit glacial melt that is otherwise difficult to document. Scientist sometimes use satellites to record glacial melt, but those techniques would not perceive internal loss occurring within a glacier, as in the ice caves on Mount Hood. Andrew Fountain, a glaciologist at Portland State University, said he didn’t know of any effort to track how much the ice inside a glacier melts from year to year, before learning of the Sandy cave system, according to a recent Oregon Public Broadcasting article on the discovery.
Studying the many different ways the world’s glaciers can melt may help the scientific community better understand how to prevent them from disappearing.
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.