Sea level rise is a much discussed symptom of climate change. While some ideas for curbing glacial melting have been proposed, few geoengineering solutions have been implemented. However, current research by University postdoctoral research associate Michael Wolovick indicates that there exists a practical solution for glacial melting.
Wolovick is currently investigating glacial sills, or walls made of rock and silt, as a way to block glaciers from exposure to warm water and keep them from melting.
“It’s not a particularly high-tech structure,” said Wolovick, “But the idea is we want to do something about the great ice sheet instability.”
Wolovick explained that glaciers grounded on bedrock below sea level are vulnerable to runaway retreat, or being diminished by melting. Surface water near glaciers is cold, but warm water under the surface of the ocean melts the glaciers. As they melt, they become even more unstable because the melted water lubricates their contact with the bedrock.
The glacial sills that Wolovick proposes will help relieve these issues by blocking the glaciers from warm water. They will also physically stabilize the ice shelves because the glaciers will be able to touch down on them.
The destabilization caused by melted water between the glacier and bedrock would not be helped by the sills alone. However, holes could also be drilled into the rock beneath ice shelves to drain this water, according to a Nature article published by Wolovick in collaboration with three other scientists.
Wolovick’s solution is unusual in its implementation of geoengineering. It is also a more focused solution than other proposals to combat climate change, such as Harvard physicist David Keith’s idea of spraying sulfuric acid into the atmosphere. The sulfuric acid would form sulfate aerosols, particles that would reflect sunlight to compensate for ozone loss.
“I really like how the solution that [Wolovick] suggests is much more local,” said Anushka Dasgupta ’19, comparing it to Keith’s plan. “It’s just a physical barrier, so it seems a lot easier to understand what the impacts of that could be and to undo it if we want to.”
Wolovick is currently testing the proposed sills using computer models. He alters factors from sill size to types of glacier breaking to test the possible forms his idea can take.
“There’s several steps of model complexity that would have to be climbed up before this could ever actually be implemented,” Wolovick said.
The Nature article co-authored by Wolovick notes that “Antarctica will be the largest contributor” to sea level rise. Wolovick said the first trials of his proposed project on real glaciers would likely be implemented in Greenland, which has smaller glaciers, is more easily accessible, and offers easier placement of the glacial sills than Antarctica. Preliminary testing will reveal whether the sills can then be tested on the larger, more critical glaciers.
Other models for curbing the melting of ice sheets have included pumping water on top of glaciers.
“It’s the only previous work I’ve seen on glacial geoengineering, but I don’t think it’s a good idea,” said Wolovick. One threat of this approach is water drainage through the glacier to the bottom, which would actually lubricate its connection to the bedrock and cause the glacier to melt more rapidly.
Wolovick explained that geoengineering is not a substitute for reducing emissions, as it does not improve other effects of climate change. He cited changes in precipitation patterns, heat waves, and droughts.
“The idea I proposed might not work if the climate warms too much in Antarctica,” Wolovick said. “The sills rely on re-grounding glaciers on bedrock, but with enough surface melting, ice shelves will simply disintegrate.”
Additional study of the glaciers is still needed to determine their melting rates and bed morphologies. Although any intervention is accompanied by some degree of risk, Wolovick and his co-authors write, “the greatest risk is doing nothing.”