In December, researchers reported that huge and growing cracks have formed in the eastern ice shelf of the Thwaites Glacier, a Florida-size mass of ice that stretches 75 miles across western Antarctica. They warned that the floating tongue, which acts as a brace to support the Thwaites, could snap off into the sea in five years. This could set off a chain reaction in which more ice cliffs are exposed, then they fracture and fall.
A complete loss of the so-called doomsday glacier could raise ocean levels by two feet–or as much as 10 feet if the collapse drags down surrounding glaciers with it, according to scientists with the International Thwaites Glacier Collaboration. It could flood coastal cities across the globe, threatening millions.
All of this raises the urgent question: What can we do to stop it from happening?
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Even if the world immediately halted the greenhouse-gas emissions driving climate change and warming the waters beneath the ice shelf, that wouldn’t do anything to thicken and restabilize the Thwaites’s critical buttress, says John Moore, a glaciologist and professor at the Arctic Centre at the University of Lapland in Finland.
“Physically stabilizing the ice sheets is the only way to prevent the collapse,” he said.
That will require what is variously described as active conservation, radical adaptation, or glacier geoengineering.
Moore has provided a number of ways people can intervene to protect key glaciers. One scheme involves creating artificial braces using polar megaprojects or other structures that encourage nature to restore the glaciers. It is hoped that engineering efforts can be made to reduce flooding and property damage in coastal cities and low-lying islands. This will also help to lower the cost of adaptation projects.
If it works, it may be possible to preserve important ice sheets for several more centuries, buying time and allowing the world to reduce its emissions and stabilize the climate.
But there would be huge logistical, engineering and legal challenges. It’s unclear how effective these interventions would be or if they could be made before the most important glaciers disappear.
Redirecting warming waters
In articles and papers published in 2018, Moore, Michael Wolovick of Princeton, and others laid out the possibility of preserving critical glaciers, including the Thwaites, through massive earth-moving projects. These projects would include shipping large quantities of material in and dredging it up to create artificial islands or berms around key glaciers. These structures would be used to support glaciers and other ice shelves as well as block warm, dense ocean water layers that melt from below.
More recently, they and researchers affiliated with the University of British Columbia have explored a more technical concept: constructing what they’ve dubbed “seabed anchored curtains.” These would be buoyant flexible sheets, made from geotextile material, that could hold back and redirect warm water.
The idea is that the new curtains will be less expensive than those previously proposed. They can also withstand iceberg collisions, and can be removed if they have any side effects. These structures were designed around Greenland’s Thwaites, Pine Island and Thwaites glaciers.
If the curtains redirected enough warm water, the eastern ice shelf of the Thwaites could begin to thicken again and firmly reattach itself to the underwater formations that have supported it for millennia, Moore says.
“The idea is to return the system to its state around the early 20th century, when we know that warm water could not access the ice shelf as much as today,” he wrote in an email.
They have explored the effects and costs of strategically placing these structures where warm water flows in and the benefits of creating a larger curtain further out in the bay. The latter approach would cost on the order of $50 billion. That’s a big number, but it’s not even half what one proposed seawall around New York City would cost.
Researchers have floated other potential approaches as well, including placing reflective or insulating material over portions of glaciers; building fencing to retain snow that would otherwise blow into the ocean; and applying various techniques to dry up the bed beneath glaciers, eliminating water that acts as lubricant and thus slowing the glaciers’ movement.
Will it work?
Some scientists have criticised these ideas. Seven researchers submitted a response in Nature to Moore’s 2018 proposals, arguing that the concepts would be partial solutions at best, could in some cases inadvertently accelerate ice loss, and could pull attention and resources from efforts to eliminate the root of the problem: greenhouse-gas emissions.
The lead author, Twila Moon, a scientist at the National Snow and Ice Data Center at the University of Colorado,