Geoengineering Polar Glaciers to Slow Sea-level Rise

Targeted geoengineering to preserve continental ice sheets deserves serious research and investment, argues an international team of researchers in a Comment published in the journal Nature.

Without intervention, by 2100 most large coastal cities will face sea levels that are more than three feet higher than they are currently.

Ice sheets that spread from continental shelves to the ocean are highly vulnerable to melting near the grounding line, which is the point at which they lift off of the bedrock and start floating on the ocean (purple). Wolovick proposes building an artificial sill — an underwater wall 3 miles long and 350 feet high — to block warm water (red) from reaching the glacier. Diagram courtesy of Michael Wolovick

Previous discussions of geoengineering have looked at global projects, like seeding the atmosphere with particles to reflect more sunlight. That’s what makes this focused approach more feasible, says Michael Wolovick, a postdoctoral research associate in Atmospheric and Oceanic Sciences and a co-author on the Comment. (Nature editors commission Comments, short articles by one or more experts that call for action and lay out detailed solutions for current problems.)

“Geoengineering interventions can be targeted at specific negative consequences of climate change, rather than at the entire planet,” Wolovick said.

The ice sheets of Greenland and Antarctica will contribute more to sea-level rise this century than any other source, so stalling the fastest flows of ice into the oceans would buy us a few centuries to deal with climate change and protect coasts, say the authors.

“There is going to be some sea-level rise in the 21st century, but most models say that the ice sheets won’t begin collapsing in earnest until the 22nd or 23rd centuries,” said Wolovick. “I believe that what happens in the 22nd or 23rd centuries matters. I want our species and our civilization to last as long as possible, and that means that we need to make plans for the long term.”

Wolovick started investigating geoengineering approaches when he realized how disproportionate the scale was between the origin of the problem at the poles and its global impact: “For example, many of the most important outlet glaciers in Greenland are about 5 kilometers (3 miles) wide, and there are bridges that are longer than [that]. The important ice streams in Antarctica are wider, tens of kilometers up to 100 kilometers, but their societal consequences are larger as well, because they could potentially trigger a runaway marine ice sheet collapse. The fast-flowing parts of the ice sheets — the outlet glaciers and ice streams — might be the highest-leverage points in the whole climate system.”

The glaciers could be slowed in three ways: warm ocean waters could be prevented from reaching their bases and accelerating melting; the ice shelves where they start to float could be buttressed by building artificial islands in the sea; and the glacier beds could be dried by draining or freezing the thin film of water they slide on.

Read full article: Princeton

Thwaites Glacier, west Antarctica, Source: NASA, Image labeled for reuse

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