Roundup: Thwaites Earthquakes, Peru Glacier Collapse Claims Lives, and an Alaskan Streamflow Study

Thwaites Glacier in Antarctica is Now Causing Earthquakes

Thwaites Glacier is one of Antarctica’s largest contributors to sea level rise from Antarctica.  Its rate of loss has doubled in the past three decades, earning it the moniker “doomsday glacier.” Understanding why it’s retreating so quickly has been a challenge, but glaciologists have recently discovered that the glacier is now generating its own seismic activity when it calves (breaks off icebergs into the ocean), which could help in unlocking the physical keys to this process. The findings were published early this year in Geophysical Research Letters. 

Read the full story on Thwaites earthquakes by Grennan Milliken on GlacierHub here.

Icebergs near the terminus of Thwaites Glacier. If it were to collapse it could raise global sea levels by ten feet. (Source: NASA)

A Catastrophic Glacier Collapse and Mudflow in Salkantay, Peru

On 23 February 2020 an enormous, catastrophic debris flow tore down the Salkantay River in Santa Teresa, Peru. This event has killed at least four people, with a further 13 reported to be missing. Given the magnitude of the flow, this number is probably uncertain. The mudflow was captured in an extraordinary video posted to YouTube.

Read the full post on the Salkantay ice/rock avalanche by Dave Petley on GlacierHub here.

A Classification of Streamflow Patterns Across the Coastal Gulf of Alaska

From the plain language abstract: “Streams provide society with many benefits, but they are being dramatically altered by climate change and human development. The volume of flowing water and the timing of high and low flows are important to monitor because we depend on reliable streamflow for drinking water, hydroelectric power, and healthy fish populations. Organizations that manage water supplies need extensive information on streamflow to make decisions. Yet directly measuring flow is cost‐prohibitive in remote regions like the Gulf of Alaska, which drains freshwater from an area greater than 400,000 km2, roughly the size of California. To overcome these challenges, a series of previous studies developed a tool to predict historical river flows across the entire region. In this study, we used 33 years of those predictions to categorize different types of streams based on the amount, variability, and timing of streamflow throughout the year. We identified 13 unique streamflow patterns among 4,140 coastal streams, reflecting different contributions of rain, snow, and glacial ice. This new catalog of streamflow patterns will allow scientists to assess changes in streamflow over time and their impact to humans and other organisms that depend on freshwater.”

Read the full study published by the American Geophysical Union here.

Source: AGU/Sergeant et al

Read More on GlacierHub:

Photo Friday: Norwegian Glacial Ice Preserves Ancient Viking Artifacts

Video of the Week: Animation Shows Frequency of Antarctic Calving Events

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Thwaites Glacier in Antarctica is Now Causing Earthquakes

Thwaites Glacier is one of Antarctica’s largest contributors to sea level rise from Antarctica.  Its rate of loss has doubled in the past three decades, earning it the moniker “doomsday glacier.” Understanding why it’s retreating so quickly has been a challenge, but glaciologists have recently discovered that the glacier is now generating its own seismic activity when it calves (breaks off icebergs into the ocean), which could help in unlocking the physical keys to this process. The findings were published early this year in Geophysical Research Letters.  

Combing through seismograph readings collected in West Antarctica during a large calving event at Thwaites on February 8th 2014, a team of researchers found evidence of two low frequency earthquakes, each about 10-30 seconds long. Their hunch—that the quakes came from the calving—was confirmed when they matched the seismograph readings with satellite images taken on the same day. 

Thwaites Glacier
The rate of ice loss from Thwaites Glacier has doubled in the last thirty years. (Source: NASA)

They also discovered high frequency blips of seismic activity that chirped on and off in the week preceding the event. Glaciologist and lead author of the study, Paul Winberry, explained to GlacierHub that in these short bursts they were actually “hearing all these little cracks start to propagate.” It was the sound of countless cracks forming and popping apart, heralding the large break about to come. 

“Frequency” refers to the behavior of shockwaves that reverberate out from the source of the earthquake. Waves repeat their motion as they travel in a peak-valley-peak-valley pattern. Waves that do this rapidly are called high-frequency and those that do it slowly are called low frequency. High frequency waves are detectable over short distances; low frequency waves over long distances.       

Thwaites is the only known glacier in Antarctica to exhibit seismic behavior, whereas glaciers in Greenland have been recorded causing earthquakes for some time. This difference can be explained by the fact that the majority of Greenland’s icebergs capsize when they break off into the water. The result is a more boisterous form of calving that produces detectable earthquakes. Why Greenland’s icebergs capsize and Antarctica’s do not has to do with the physical makeup of each landmass’s ice sheets and where they start to float on the water.

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. Antarctic glaciers flow outwards horizontally, and continue on into the water as huge floating shelves that stretch miles out to sea. 

“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,” said Winberry. “It’s completely different.”

The other key component of capsizing is the physical shape. Greenland’s icebergs are top-heavy. “They’re taller than they are wide. They’re not stable, so when they break off they want to flip over,” said Winberry. 

Tim Bartholomaus, a glaciologist from the University of Idaho who has studied Greenland’s glaciers told GlacierHub that the capsizing icebergs bang into the front of the glacier as they’re flipping over and that generates the earthquake. “As they’re rotating en masse, they’re putting their shoulder against the back of the terminus and giving it an enormous push as they’re rotating.” 

Icebergs near the terminus of Thwaites Glacier. If it were to collapse it could raise global sea levels by ten feet. (Source: NASA)

These collisions don’t normally occur during calving in Antarctica because the ice sheets are far bigger, already floating on the water, and terminate far from the grounding line. “Those icebergs break off and form New England or Delaware-sized chunks. And when that happens they kind of slowly drift away,” said Winberry. That Thwaites is now generating detectable seismic earthquakes means one thing: its icebergs are likely capsizing because its terminus is now close to the grounding line. 

“The fact that Thwaites is now doing this slab capsize style of calving, that means that it is breaking off right at the point where the glacier is hitting the ocean,” said Bartholomaus. 

The capsize calving at Thwaites on February 8th 2014 sent low frequency waves traveling—and shaking—through the ice and land underneath for hundreds of miles. It generated enough energy to show up on seismometers over 900 miles away as a magnitude 3.0 earthquake.  

Over the last three decades, the Thwaites glacier has lost about 600 billion tons of ice. Some scientists fear that with an increased rate of 50 billion tons of ice lost a year in recent times, runaway instability of the glacier may already be underway. Total collapse of the glacier would raise global sea levels by 10 feet. Thwaites’ newfound seismic activity suggests that its retreat has now reached land. 

“It’s lost all of its floating ice,” Winberry told GlacierHub. “The floating extension has basically disappeared. So to understand the future retreat of the glacier, we need to understand this different style of calving behavior.” 

While that may be concerning, it also gives scientists a new tool for better understanding the process of calving at Thwaites. So far, glaciologists have relied heavily on satellite imagery for studying large scale calving events in Antarctica, but satellites usually only take one picture a day or every two days.  “A lot happens between those two days. In these calving events, the flipping of these icebergs and actual breaking apart can happen over minutes to hours,” said Winberry. Being able to “listen” to them unfold in near real time adds a whole new element. 

“That is going to help us unravel the physics of how these icebergs actually form, which is what we need to know to produce better predictions of future retreat of this glacier” said Winberry. 

Read More on GlacierHub:

Video of the Week: Animation Shows Frequency of Antarctic Calving Events

A Catastrophic Glacier Collapse and Mudflow in Salkantay, Peru

Roundup: A New Glacier Surge Study, Three Decades of Caucasus Glacier-Debris Change, and Mining Expansion in Greenland

Video of the Week: First Footage From Beneath Thwaites Glacier

In this week’s Video of the Week take the first look beneath Thwaites Glacier, the Florida-size slipping cork of ice keeping the West Antarctic Ice Sheet intact. On Monday Earther published the video with the story “‘Goosebumps’: Researchers Capture First Video From Under Antarctica’s Most Endangered Glacier.”

Video republished with permission from Earther

Last month researchers used hot water to bore a hole to the bottom of the glacier, opening an access point for data collection and imagery. The effort is a product of MELT, one component of eight multi-disciplinary research proposals led by a team of American and British scientists from the International Thwaites Glacier Collaboration Project (ITGC), to better understand how the warm water is melting the glacier at the grounding line.

The footage was taken using Icefin, “a small, under-ice, robotic oceanographer,” from the Georgia Institute of Technology––one of five universities involved with MELT. “Her [Schmidt’s] video is like seeing the surface of the moon for the first time,” American Geophysical Union president and glaciologist Robin Bell told Earther. “The video gives me goosebumps.”

Like the surface of the moon indeed. According to Earther’s video, “More people have walked in space than have been the remote, harsh environment of Thwaites.”

Icefin aims to characterize sub-ice environments using sonar, chemical, and biological sensors to explore ice and water conditions around and beneath ice shelves (Source: Georgia Institute of Technology).

Read More on GlacierHub:

Photo Friday: Thwaites Glacier Bore Hole Drilled

Project Aims to Better Understand “Doomsday” Glacier

Glacial Geoengineering: The Key to Slowing Sea Level Rise?

Photo Friday: Thwaites Glacier Bore Hole Drilled

If there is a ‘doomsday glacier‘ Thwaites Glacier in Antarctica is it. The massive glacier is one of the fastest melting glaciers in the world and has the potential to destabilize the entire West Antarctic ice sheet––a scenario which would raise global sea levels an average of ten feet.

A team of scientists led by David Holland and Keith Nicholls––from the International Thwaites Glacier Collaboration Project (ITGC)––are using hot water to drill holes through the glacier. On January 8 the first bore hole was drilled, opening a 590 meter access point directly to the bottom of the glacier.

The goal of the project––MELT––is to better understand how the warm water is melting the glacier at the grounding line. Ultimately, researchers hope the data gleaned will allow the glacier’s potential sea-level contribution to be more accurately predicted.

On Twitter, the handle @HotWaterOnIce is actively providing updates from Thwaites’ surface, providing an on-ice view of the depth and breadth of the research taking place.

Read More on GlacierHub:

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Solar Geoengineering Could Limit Sea-Level Rise from Cryosphere

Of the many impacts caused by climate change, sea-level rise threatens to be one of the most devastating due to the thermal expansion of the oceans and the melting of ice and glaciers on land. These impacts, along with numerous others related to rising global temperatures, may in the future motivate a country, a group of countries, or even a very rich individual to pursue solar geoengineering, a controversial proposal for limiting the amount of solar radiation that reaches the Earth’s surface. A recent study in The Cryosphere assessed the efficacy of such a solar geoengineering attempt at limiting global sea-level rise.

Geoengineering, as it relates to climate change, falls into two categories. The first, atmospheric carbon removal, entails physically removing carbon dioxide from the air to reduce greenhouse gas concentrations and limit temperature rise. The second, solar geoengineering, involves injecting sulfur dioxide or another aerosol into the stratosphere to reflect a portion of incoming solar radiation, again limiting temperature rise.

Because of the temperature-reducing effect of solar geoengineering, research suggests that such a proposal would also reduce sea-level rise. However, just how effective solar geoengineering could be in limiting sea-level rise had not yet received sufficient research, according to Peter Irvine, the lead author of the study, who spoke with GlacierHub. Irvine and his team of scientists hoped to “shed some light on the complexities of the sea-level rise response to solar geoengineering, make an initial evaluation of its efficacy, and to bring this issue to the attention of the cryosphere research community,” Irvine told GlacierHub.

Photo of the sun. Solar geoengineering could limit the amount of sunlight that reaches the Earth’s surface (Source: climatemediat/Twitter).

Initially, the researchers conducted a literature review on the small number of studies that explored the cryosphere’s potential response to solar geoengineering. A 2009 study that examined the Greenland Ice Sheet found that under a scenario where atmospheric concentrations were quadrupled, solar geoengineering could slow or even prevent the collapse of ice sheets. Conversely, a 2015 study determined that while solar geoengineering could slow melting, glaciers and ice sheets would not recover to past states. Lastly, a 2017 study focusing on high-mountain Asia, found that solar geoengineering would stop temperature increases; however, 30 percent of glaciated area would still be lost.

Following the literature review, the researchers evaluated the potential effect of solar geoengineering on three aspects of sea-level rise. The first aspect was thermosteric sea-level rise, or more simply, the thermal expansion of ocean waters. Because temperature is the dominant influence on thermosteric sea-level rise (warmer water is less dense than cooler water), the decrease in solar radiation reaching the Earth’s surface due to solar geoengineering would limit sea-level rise.

Secondly, the researchers examined solar geoengineering’s effect on the surface mass balances of glaciers and ice sheets. Surface mass balance is primarily affected by the surface melt rate, which is the result of the availability of energy at the surface of the ice. Thus, a change in solar radiation reaching the Earth’s surface would likely reduce surface melt. The analysis of large volcanic eruptions offers an analogous example to what might happen to surface melt if solar geoengineering were pursued because the dust and ash released during an eruption blocks some incoming solar radiation.

Photo of Pinatubo eruption Solar geoengineering could have a similar effect to the 1991 eruption of Pinatubo (Source: USGS/Twitter).

One study examined by the researchers showed that surface mass balances in Greenland were at their maxima in the year after the El Chicón and Pinatubo eruptions in 1982 and 1991, respectively. Similarly, another study in Greenland found that in the years following the El Chicón and Pinatubo eruptions, surface runoff was the third lowest and lowest, respectively, between the years 1958 and 2006, further reinforcing the expectation that solar geoengineering would limit surface mass balance reductions.

In addition to its effect on temperature, solar geoengineering would also affect the global hydrologic cycle and subsequently sea-level rise. Warming temperatures due to climate change will likely lead to more precipitation worldwide; however, if solar geoengineering is pursued, this increase could be offset. This precipitation change would affect both Greenland and Antarctica, according to Irvine.

In Greenland, surface melt changes, not precipitation accumulation, are the primary influence on surface mass balances; therefore, solar geoengineering would likely have a positive effect by reducing temperatures, with the decrease in precipitation unlikely to lead to mass balance decline. In Antarctica, on the other hand, increased precipitation due to climate change has had a positive effect on surface mass balance, thus a decrease in precipitation due to solar geoengineering would negatively impact mass balances.

The third and final sea-level rise aspect examined by the researchers to evaluate the efficacy of solar geoengineering was ice lost through calving and eventual ice-sheet collapse. Calving, the scientific name for icebergs breaking off a glacier at its terminus, depends on the speed at which ice flows, which itself is driven by climatic changes.

Photo of a calving glacier in Greenland A calving glacier in western Greenland (Source: NASA_ICE/Twitter).

In Antarctica, warming water known as circumpolar deep water (CDW) is the primary driver of calving. CDW is pushed below and then up into glacial cavities by surface winds, where the warm water melts the ice. This melting drives calving and leads to the thinning of glaciers.

While solar geoengineering would likely lower air temperatures, it is unlikely to reduce the temperature of CDW and limit melting and subsequent calving from below. In addition, a 2015 study found that solar geoengineering is unlikely to limit the upwelling of CDW and could even increase upwelling. However, this finding has yet to be replicated, according to Irvine, and it is not clear whether the results are exclusive to the model used.

There is also no guarantee that solar geoengineering would be able to prevent glacial collapse due to marine ice sheet instability. This collapse occurs when a glacier retreats past its grounding line (where ice meets underlying bedrock) and continues to retreat inland until it reaches another stabilizing ridge. The process might already be occurring at West Antarctica’s Thwaites and Pine Island glaciers, which are extremely vulnerable due to the sloping topography upon which they rest.

Nevertheless, retreat and possible collapse might be preventable, says a 2016 study. It showed that returning water to cooler conditions reversed glacial retreat. This finding indicates solar geoengineering may be useful to prevent marine glaciers from destabilizing. While encouraging, it remains likely that certain glaciers, especially those in West Antarctica, will continue to experience significant ice loss regardless of whether solar geoengineering is pursued or greenhouse gas emissions are dramatically reduced.

Based on their study, the researchers lay out four areas in need of future research. First is the need to evaluate the sea-level rise response to solar geoengineering scenarios in conjunction with climate change scenarios so that the efficacy of solar geoengineering and greenhouse gas emissions reductions can be compared. Second is the need to employ regional models of surface mass balance in order to assess the effectiveness of solar geoengineering to limit mass balance losses. Third, the researchers recommend additional evaluation of the effect of solar geoengineering on the CDW upwelling and stability of glaciers and ice-shelves. Finally, the researchers recommend the evaluation of sea-level rise risk, alongside the numerous other risks and challenges associated with solar geoengineering.

Diagram of glacier melting from below Diagram depicting a glacier melting from below due to warming ocean currents (Source: EuroGeosciences/Twitter).

The potential for solar geoengineering to limit sea-level rise from the cryosphere is still up for debate, but as this study shows, it may have the potential to reduce temperature and curb some aspects of sea-level rise, including surface mass balance losses and ocean thermal expansion. However, for other aspects, mainly the melting of glaciers from below by warm waters, it may be unlikely that solar geoengineering can limit sea-level rise contributions. Nonetheless, when it comes to the society-altering impact of sea-level rise, solar geoengineering could be a part of humanity’s response.

Project Aims to Better Understand “Doomsday” Glacier

On April 30, 2018, the largest joint United States-United Kingdom Antarctic project since the 1940s was announced at the British Antarctic Survey in Cambridge. The International Thwaites Glacier Collaboration (ITGC) will focus on the Thwaites glacier of West Antarctica, one of the world’s largest and fastest melting glaciers.

The Thwaites has already contributed to 4 percent of observed global sea-level rise, but the rapid melting of the Thwaites is not scientists’ only concern. The glacier acts as a sort of plug, protecting the rest of the West Antarctic ice sheet from melting. But if the Thwaites were to collapse, most of the West Antarctic ice sheet would be destabilized, likely leading to its impending collapse. This so called “‘Doomsday”’ scenario would cause sea levels to rise 10 feet on average across the Earth.

Photo of the Thwaites Glacier from above
Aerial view of the Thwaites Glacier (Source: Earth Insitute/Twitter).

The ITGC, a $25 million, five-year collaboration between the U.S. National Science Foundation and UK Natural Environment Research Council, will include six scientific field studies with over 100 scientists using a number of different technologies and techniques to analyze the changes to the Thwaites and surrounding ocean.

Getting to the white expanses of the Thwaites is no easy task due to its remote location in Antarctica. In fact, only a handful of people have actually stood on the glacier. For this reason, most scientific research takes place at the more accessible national research stations, according to Jessica O’Reilly, an anthropologist at Indiana University who studies the Antarctic. “Deep field” projects like the ITGC are much rarer because of logistical challenges like coordinating multiple flights to remote areas in erratic weather and the sheer cost of such endeavors, she added.    

This threshold system is further unique to West Antarctica, according to O’Reilly, because it is a marine ice sheet, meaning its grounding line (where ice meets the underlying bed) is under water instead of on land. “Therefore, not only does air surface temperature interact with the ice sheet, but the warming ocean underneath it can also destabilize it,” she said. This distinction makes the Thwaites and rest of the West Antarctic extremely vulnerable to melting, a reality that has inspired a geoengineering proposal to build underwater walls at the grounding line of glaciers like the Thwaites to slow down melting and possibly prevent collapse.

NERC figure depicting the project's different missions
NERC figure depicting the project’s different missions (Source: NERC).

The U.S.-UK research endeavor and its six-field missions will assess just how at risk the Thwaites is to a catastrophic collapse. One of these missions will be led by Penn State Glaciologist Sridhar Anandakrishnan, who spoke to GlacierHub about the project. In Antarctica, Anandakrishnan and his team will be conducting geophysical surveys to characterize the base of the glacier. The surface where ice meets bedrock affects the way the Thwaites flows and is important for projecting how the glacier will retreat. Presently, according to Anandakrishnan, there is a need for improved information on this surface at the Thwaites. “Is it soft or hard? Is it smooth or rough? And so on,” he said.

To obtain this information, Anandakrishnan’s team will use both seismic and radar techniques. From a seismic approach, small explosives will be set off right below the glacier’s surface. The team will then listen for the explosion’s echo from the bottom of the glacier. Based on the time it takes for the echo to return and its strength, the team will be able to better understand the surface where glacial ice meets bedrock.

The radar approach involves a similar process where the team will emit a radar pulse, detect the reflected pulse, and interpret the time and amplitude of the returned pulse for information such as ice thickness, according to Anandakrishnan.

Thwaites Glacier from above
The seemingly endless expanses of the Thwaites Glacier (Source: Hannah Hickey/Twitter).

In addition to this field mission, the five others will examine the Thwaites from different focuses. These include measuring the glacier’s melting at its grounding line; measuring ocean circulation and glacial thinning underneath the floating portion of the glacier using autonomous submersibles; sampling bedrock beneath the glacier to better understand its past retreats and recoveries; analyzing the glacier’s margins to study what controls its width and speed; and examining sediments deposited in the ocean near the glacier to reconstruct past environmental changes and the Thwaites’s response to these changes.

Two other non-field missions will utilize computer models and simulations to assess processes that could cause the rapid retreat and collapse of the glacier and to improve projections on its future behavior and contribution to sea level rise.  

Photo of Boaty McBoatface
The autonomous submersible Boaty McBoatface which will participate in the project (Gizmodo/Twitter).

According to Anandakrishnan, these missions fall in line with one of the main goals of the ITGC: to better understand the Thwaites by improving modeling and projections of the future state of the glacier. Even without a collapse, the Thwaites could contribute up to one meter of sea-level rise over the next century, a change that would have devastating effects on the world’s coastal communities.

If the goals of the project can be accomplished, “we can better estimate what this glacier would do under various future climate scenarios,” Anandakrishnan said. Overall, the U.S.-UK Antarctic project will be a big step forward for humanity’s understanding of a glacier that could have a profound impact on society if it were to collapse.