Geoengineer Polar Glaciers to Slow Sea-Level Rise

Slowing down glacial melting through geoengineering may help avert catastrophic sea-level rise due to global warming.

If average global temperatures increase by 2 degrees Celsius [3.6°F] by 2050, global sea levels will rise by about 20 centimeters on average. By 2100, sea levels around the world’s major coastal cities are projected to be more than one meter higher than today, displacing millions of people.

“If nothing is done, 0.5–5% of the world’s population will be flooded each year after 2100.”

The source of most of the water added to the world’s oceans will come from melting ice sheets in Greenland and Antarctica. Some scientists are proposing ways to slow down the loss of ice sheets through geoengineering.

The Jacobsohn glacier in western Greenland would lend itself well to test the feasibility of glacial geoengineering.

The Jacobsohn glacier in western Greenland is retreating at a rapid pace. Warm water washing in from the Atlantic is causing rapid melting at the glacier’s base. To stem the influx of warm water, geoengineers suggest the construction of a 100-meter-high wall on the seabed across a 5 km wide fjord in front of the glacier, using gravel and sand from Greenland’s continental shelf.

“Glaciologists and engineers should establish the scientific viability of these projects through fieldwork and computer modelling.”

The project would be comparable to other civil-engineering feats, such as the Suez Canal in Egypt or the Three Gorges Dam in China. Although melting water from the Jacobsohn glacier contributes only a small percentage to global sea water rise, the proposed berm project would lend itself well to test the feasibility of glacial geoengineering.

In Antarctica, a proposed engineering project seeks to slow down glacial breakup with artificial islands and berms.

In Antarctica, most of the water adding to the world’s oceans comes from floating ice shelves, which are melting at an ever-faster pace due to warming air and ocean water. Warm ocean currents below the West Antarctic ice sheet are accelerating glacial melting and the formation of floating ice shelves at the Pine Island and Thwaites glaciers.

“The Pine Island and Thwaites glaciers in West Antarctica are the largest potential sources of sea-level rise over the next two centuries.”

Geoengineers propose constructing berms and islands in front of the two glaciers to fortify them and slow down glacial breakup. Furthermore, they suggest the construction of a large berm to prevent warmer water from reaching the glaciers. The berm would require 60 times more material than the proposed Jacobsohn wall, possibly requiring shipping building material from outside Antarctica.

Geoengineers are?looking into ways to freeze glacial meltwater at the base.

Geoengineers are also looking for ways to stave off glacial melting from the base of the Pine Island glacier. Sliding ice streams at its base cause frictional heat, generating water that precipitates glacial sliding toward the sea. One proposed project envisions circulating cooled brines underneath the glacier to freeze the glacial meltwater at the base.

If glacial geoengineering is feasible, its potential risks will be smaller than?letting accelerated glacial melting run its course.

Glacial geoengineering is expensive, yet the price tag pales compared to the billions of dollars it would cost to build sea walls around vast stretches of coastline and relocate millions of coastal dwellers.

“Should we spend vast sums to wall off all the world’s coasts, or can we address the problem at its source?”

In Greenland, the megaprojects would impact local communities and the local fishing and tourism industries – yet rapid sea-level rise would cause even more disruption. Marine ecosystems will be impacted not only by the construction process, but also by slowed glacial melting, which will reduce the availability of nutrients from glacial sediments.

“Implementation would require global consent.”

Still, fortifying glaciers will have less of an environmental impact than other geoengineering projects, such as stratospheric aerosol injection. Of course, glacial geoengineering does nothing to mitigate global warming. But should the world fail to drastically reduce greenhouse gas emissions in the coming years, glacial geoengineering is a way to soften the environmental blow of a warming planet.