Glacial Geoengineering: The Key to Slowing Sea Level Rise?

The rapid collapse of some of the world’s biggest glaciers due to climate change will have devastating consequences for our planet’s coastlines due to sea level rise. Compounding this issue is the fact that many of these coastlines are heavily populated and developed. A recent proposal, first reported in The Atlantic, aims to avert potential catastrophe by turning to geoengineering through the construction of massive underwater walls, called sills, which would be built where glaciers meet the ocean in Antarctica and Greenland.

The idea is the work of Michael Wolovick, a glaciology postdoctoral researcher at Princeton University. The uniqueness of his geoengineering proposal is its focus on a consequence of climate change, in this case sea-level rise, as a result of glacial collapse, rather than a focus on decreasing greenhouse gases (GHG), the root cause of climate change. Many geoengineering proposals attempt to slow down or even reverse the Earth’s rising temperatures as an alternative to GHG mitigation through the addition of aerosols like sulfur dioxide to the atmosphere or increase in the reflectivity of clouds, while others explore ways to capture and subsequently sequester carbon.

Photo of the Jakobshavn glacier in Greenalnd.
The calving front of the Jakobshavn glaicer in western Greenland. The Jakobshavn is a potential site for the proposal’s walls (Source: NASA Goddard Space Flight Center/Creative Commons).

When asked about the inspiration behind his distinct work, Wolovick told GlacierHub he has been fascinated by the large scale societal implications that glacial collapse could have, given the relatively small scales of the glaciers themselves. The so called “doomsday glacier,” the Thwaites of West Antarctica, is only around 100 km wide, for example, but its collapse would swiftly destabilize large parts of the West Antarctic ice sheet, potentially leading to sea level rise of up to 13 feet in some parts of the world.

So how does Wolovick’s plan work? It starts with an engineering project of unprecedented scale, the construction of large underwater walls, composed of an inner layer like sand and an outer layer of boulders. These walls would be strategically built at the grounding line, where a glacier’s leading edge meets the ocean, of the world’s most unstable glaciers. These walls would be built primarily in Antarctica and Greenland where many glaciers extend beyond the land to float on the ocean.

Figuredetailing how ocean ending glaciers are melted from below
Figure detailing how ocean-ending glaciers are melted from below. The walls from this proposal would be placed in front of the grounding line pictured here (Source: Smith et al.).

Glaciers that extend from land into the ocean are exposed to both warming air and water temperatures. Warmer sea water melts these glaciers from below in addition to the melting that occurs from the air above, causing them to melt faster than glaciers solely confined to land. This is where the walls built on the ocean-floor would come into play. Once in place, the purpose of these barriers would be “to block warm water so you could reduce the melting rate, and also to provide pinning points that the ice shelf could reground on as it thickens,” according to Wolovick. In addition, because the glaciers are already floating, the walls would prevent warm water from moving further inland and increasing melting rates there.

Would these walls work in actuality? Wolovick’s computer modelling is in its early stages, but some models show glaciers stabilizing after walls are put in place, with some glaciers actually gaining in mass. This possible stabilization would buy some time to act decisively on adaptation to sea level rise and perhaps allow the prevention of disastrous ice sheet collapse altogether. Still, Wolovick admits a lot more work needs to be done in the future including the development of better ocean models to see if the walls would block warmer water in the way intended, allowing a glacier to stabilize.

Photo of a calving front of a glacier in West Antarctica
The calving front of a glacier in West Antarctica (Source: NASA Goddard Space Flight Center/Creative Commons).

While the proposal has the potential to slow glacial melting, Lukas Arenson, principal geotechnical engineer at BGC Engineering Inc. who spoke with GlacierHub about the proposal, says it is still in its very early stages, and there are many questions that need to be answered before implementation. One of Arenson’s principle concerns is “the enormous costs for building such a sill or a dike in a stable manner in these areas as it requires some major engineering and construction efforts.” Wolovick recognizes that his proposal would require placing a massive amount of material in front of glaciers, especially for wide ones such as the Thwaites.

There are also a plethora of engineering matters that need to be addressed. First, the foundations for the walls would need to be well protected. This protection could take the form of boulders and concrete elements or additional sills built in front of or at an angle to the main sill to redirect currents that could compromise its effectiveness, according to Arenson. Secondly, the seafloor on which the walls would be built could be “quite unstable and soft at places so that placing additional fill for a sill may be extremely challenging, potentially causing some local instabilities,” Arenson added. Finally, Wolovick states that it may be necessary to build the wall “underneath floating ice shelves, or in the vicinity of dense iceberg melange.” These efforts would further complicate what would already be a mega-engineering project.

Photo of an iceberg in Pine Island Bay
An iceberg floats in West Antarctica’s Pine Island Bay where the Thwaites glacier ends Source: NASA Goddard Space Flight Center/Creative Commons).

In addition to the technical aspects of the proposal, there are other issues to consider. There is also the question of where the material for the walls would come from and whether the walls might have detrimental impacts on sensitive Antarctic sea floor environments.

However, despite the many challenges ahead, the time is right to take action. As climate change progresses and glaciers around the world continue to melt, global sea levels creep up. One recent study projects an increase of 80 to 150 cm (close to five feet) by 2100, which would flood land currently inhabited by 153 million people. This geoengineering proposal will by no means solve every problem associated with climate change, like unabated human emissions of greenhouse gases, but with millions living along the coasts, it could provide humanity with something always in short supply, time.

Below the Ice: Subglacial Topography in West Antartica

When traversing the broad white expanses of West Antarctica’s Pine Island Glacier (PIG) by snowmobile, you might think the main attraction would be the surface of the rapidly receding river of ice. However, for the authors of a recently published study in Nature Communications, the real draw was not the surface but the rock beneath—the subglacial topography of Antarctica’s most rapidly melting glacier.

Photo of snowmobile pulled radar
Snowmobile pulling survey radar on Pine Island Glacier (Source: Damon Davies/British Antarctic Survey).

Utilizing ice penetrating radar towed by snowmobile, the study’s authors were able to compile the first high-resolution maps of PIG’s underlying bed topography. What sets these maps apart from previous surveys is the detail and diversity of the rugged underlying landscape according to Ted Scambos of the National Snow & Ice Data Center who was not one of the authors of the study. Where previously conducted airborne studies found relatively level topography, this work showed more varied, and often rugged topography—findings that earlier studies had missed, because of the inability of planes to conduct very close parallel surveys.

Why is improved glacier bed delineation crucial for analyzing and predicting glacial retreat rates? It has to do with basal traction or, simply, bottom ice flow. Although we might imagine a glacier sliding as smoothly as an ice cube on a table on a hot summer day, in fact glacial movement is often slowed by two factors, friction and drag. The first of these components is the friction where ice meets the bed below. This factor is highly dynamic, changing as ice melts, flows, and refreezes; friction is also affected by subglacial till, sediment in the glacier bed which was eroded by the glacier, as it moves and freezes.

The second factor, drag, is the more static component of glacial movement. It reflects the size and orientation of undulations in the bedrock below. The net result is the sum of the first, more variable component and the second, more constant component. But earlier work had measured only the sum of the two—making it difficult to predict how the sum might vary. This study marks a major step in removing this limitation. Researchers were able to estimate the two components separately and come up with more precise predictions.

Ariel view of Pine Island Glacier meeting the sea (Source: NASA Ice/Creative Commons).

The glaciers of remote Pine Island Bay (PIB) have received a good deal of attention lately. In May, Rolling Stone published an article examining the Thwaites glacier, West Antarctica’s other rapidly shrinking glacier, and its contribution to rapid sea level rise. Then, in November, Grist published a piece titled “Ice Apocalypse” on the possibility of a rapid glacier collapse in PIB.

Pine Island Glacier, one of the most rapidly retreating glaciers in Antarctica, is estimated to have contributed up to 10 percent of observed global sea level rise, according to the study’s authors. Because of already problematic sea level rise and the societal threats posed by the rapid collapse of these glaciers, many studies have attempted to project the PIG’s future retreat. However, despite all of the focus on the PIG’s retreat, one condition has remained uncertain: the slowing of the glacier’s seaward movement, due to the forces deep below the surface where ice meets terrain.

Photo of figure showing Pine Island subglacial topography
Pine Island subglacial topography derived from study observations (Source: Bingham et al.).

Previous survey methods were unable to separately resolve glacial friction and drag. They could only measure the sum of the two, leading to inaccuracies in ice sheet models that predict retreat rates. These inaccuracies contributed to high variability in bottom ice flow predictions. Given the improved clarity of bed topography observed in this study, the authors were able to conclude that previous inconsistencies must be associated with an incomplete picture of topography beneath glaciers.

The study’s observations of the PIG painted a detailed picture of the landscape beneath the ice. Utilizing these observations, the authors were able to compare them to satellite data outlining the glacier’s recent movements and shrinkage. The comparisons revealed an interesting relationship, the movement of the glacier differed in its tributaries. What was the reason for this variation? It turns out that the slower advancing tributaries corresponded to rougher bottom terrains, with the coarse tributaries, for example, advancing toward the coast where melting occurs, two to three times slower than their smoother counterparts. These findings indicate that bedrock undulations under the PIG impact the glacier’s flow considerably more than changes in friction, a result not previously observed.This discovery allows researchers to make more precise predictions, by summing each of the different tributaries of PIG.

Photo of Thwaites glacier.
Thwaites Glacier, the other rapidly shrinking glacier in Pine Island Bay (Source: NASA’s Marshall Space Flight Center/Creative Commons).

The study shows the large influence of subglacial topography on the retreat of PIG, a topic of great importance to society for its potential disastrous impacts. While the results reveal the importance of these landscapes for glacial recession, the authors note that more research is needed to better measure terrain beneath glaciers. Specifically, they underscore the significance of these needed improvements for PIG’s counterpart, the Thwaites glacier. Like PIG, Thwaites appears to have similar diversity in underlying topography. Nonetheless, the glacier has exhibited a rapid recent retreat, faster than that of even the smoothest PIG tributaries. This is a disturbing fact given that the study’s authors state that the glacier has the “potential for rapid and irreversible retreat, and a considerable contribution to sea-level rise.”

How fast the glaciers of PIB and West Antarctica retreat in the future is still difficult to predict. Nevertheless, as exemplified by this study, scientists continue to develop better methods and models in the face of extreme conditions in one of the most remote and inhospitable places on Earth. But while remote, what happens in the coming years to the ice in PIB has the potential to change the world.

Roundup: Glacier Paddleboarding and Ice Loss in the Southern Hemisphere

Paddleboarders soak up splendors of Glacier Bay for 4 days

Paddleboarding Glacier Bay
Michelle Eshpeter views ice up close as she paddleboards near McBride Glacier in Glacier Bay National Park.
Courtesy of Alaska Dispatch News / Sean Neilson.

“A typical summer day in 3.3-million-acre Glacier Bay National Park and Preserve might see cruise boats, kayakers and anglers on the water, hikers on shore, flightseers in the air. And increasingly, paddleboarders paddling among ice floes.”

Read more about this new trend here.

 

Studying glaciers before they vanish

Thwaites Glacier“[A] just-released report by the U.S. National Academy of Sciences…. concluded that the National Science Foundation — which runs U.S. Antarctic programs — should make research on Antarctica’s sea level implications its top priority, with a particular emphasis on West Antarctica. That’s because much of its ice is below sea level and thus ‘vulnerable to a runaway collapse process known as marine ice sheet instability.’

‘There is an urgent need to understand this process in order to better assess how future sea level rise from ice sheets might proceed,’ the report stated.”

Click here to read more.

New Zealand’s glaciers have shrunk by a third – report

“The government report released on Wednesday says the volume of glacier ice has dropped by 36 percent since 1978 because of rising temperatures. Andrew Mackintosh of Victoria University’s Antarctic Research Centre said globally there was no doubt that human influences had caused glaciers to retreat. He said it has yet to be scientifically demonstrated in New Zealand, but it was very likely humans have played a part.

‘There’s no doubt that New Zealand glaciers have lost a lot of ice during that period, especially since 2008 we’ve seen a rapid loss of ice in the Southern Alps and iconic glaciers like Franz Josef and Fox have retreated dramatically.'”

To read more, click here.

 

Roundup: “Wild card” glaciers, luxury ice cubes, & glacial dynamics

This West Antarctica glacier is a ‘wild card’ for world’s coastlines

An edge of the Thwaites Ice Shelf.
An edge of the Thwaites Ice Shelf. Courtesy of Jim Yungel / NASA

“Scientists who have been raising alarms about the endangered ice sheet of West Antarctica say they’ve identified a key glacier that could pose the single most immediate threat to the world’s coastlines – and are pushing for an urgent new effort to study it. The glacier is not one that most Americans will have even heard of – Thwaites Glacier along the Amundsen Sea. It’s a monstrous body that is bigger than Pennsylvania and has discharged over 100 billion tons of ice each year in recent years.

The glacier is both vast and vulnerable, because its ocean base is exposed to warm water and because of an unusual set of geographic circumstances that mean that if it starts collapsing, there may be no end to the process. But it’s also difficult to study because of its location – not near any U.S. research base, and in an area known for treacherous weather. As a result, the researchers are also calling for more support from the federal government to make studying West Antarctica’s glaciers, and Thwaites in particular, a top priority.”

To read more about the Twhaites ice shelf, click here.

Luxury ice cubes? Greens slam ‘insane’ plan to carve Norway glacier

 

Courtesy of svaice.com  “A controversial plan to harvest ice cubes from a melting Norwegian glacier and sell them in luxury bars across the globe has drawn criticism from the head of WWF Norge, who said that such an idea proves the world has gone completely insane….
The idea to use parts of Svartisen – mainland Norway’s second largest glacier which is projected to melt over the next century – is being pushed forward by Norwegian company Svaice. In FebruarySvaice won a grant from the local Meloy municipality, which is enthusiastically backing the project and is due to meet on Wednesday to decide on the project’s future.”
Read more here.

Observed latitudinal variations in erosion as a function of glacier dynamics

UBC scientist Michele Koppes
UBC scientist Michele Koppes. Courtesy: Michele Koppes

“Climate change is causing more than just warmer oceans and erratic weather. According to scientists, it also has the capacity to alter the shape of the planet. In a five-year study published today in Nature, lead author Michele Koppes, assistant professor in the Department of Geography at the University of British Columbia, compared  in Patagonia and in the Antarctic Peninsula. She and her team found that glaciers in warmer Patagonia moved faster and caused more erosion than those in Antarctica, as warmer temperatures and melting ice helped lubricate the bed of the glaciers.

“We found that glaciers erode 100 to 1,000 times faster in Patagonia than they do in Antarctica,” said Koppes. “Antarctica is warming up, and as it moves to temperatures above 0 degrees Celsius, the glaciers are all going to start moving faster. We are already seeing that the ice sheets are starting to move faster and should become more erosive, digging deeper valleys and shedding more sediment into the oceans.”

To learn more about the study’s findings, click here.