Efforts to reduce the impact from glacier melting could help mitigate the worst effects of global warming, researchers have claimed.
According to a new study published in the European Geosciences Union journal The Cryosphere, such projects to hold off glacier melting could slow down the collapse of ice sheets and limit the forecast rise in sea-levels.
While reducing emissions still remains the most effective way to stop climate change and its dramatic effects, the scientists say an intervention similar in size to existing large civil engineering projects could have a 30 per cent chance of success.
They added that an even larger project would have better odds of holding off ice-sheet collapse.
Thwaites Glacier could easily trigger a runaway [West Antarctic] ice sheet collapse that would ultimately raise global sea level by about three metres
"Doing geoengineering means often considering the unthinkable," said study author John Moore, a scientist at Beijing Normal University, China.
The term 'geoengineering' is usually applied to large-scale interventions to combat climate change.
But instead of trying to change the entire climate, Moore, along with study co-author Michael Wolovick, a researcher at Princeton University's Department of Geosciences, said we could instead apply a more targeted approach to limit one of the most drastic consequences of climate change: sea-level rise.
Their glacial geoengineering idea involves making changes to the geometry of the seafloor near glaciers that flow into the ocean, forming an ice shelf, to prevent them from melting further.
One idea would be to build a wall underwater to block warm water reaching an ice shelf's base
This would be most effective at bigger glaciers, such as the Britain-sized Thwaites ice stream in West Antarctica, which is retreating fast.
"Thwaites could easily trigger a runaway [West Antarctic] ice sheet collapse that would ultimately raise global sea level by about three metres," explained Wolovick. "This could have dramatic effects to the millions of people living in the world's coastal areas."
The team looked at two different glacial-geoengineering designs for the study. One idea would be to build a wall underwater to block warm water reaching an ice shelf's base, which is very sensitive to melting. Then a more simple design consists of constructing artificial mounds or columns on the seafloor, which wouldn't block warm water but could support and hold back the glacier, helping it regrow.
"In either case, we are imagining very simple structures - simply piles of sand or gravel on the ocean floor," says Wolovick.
The team ran computer models where they applied these designs to Thwaites Glacier, which is projected to be the largest individual source of future sea-level rise.
A more simple design consists of constructing artificial mounds or columns on the seafloor, which wouldn't block warm water but could support and hold back the glacier
Despite encouraging results, the scientists won't be starting the project any time soon. While the simplest design would be similar in scale to existing engineering projects, it would be built in one of Earth's harshest environments. So, the engineering details still need to be worked out, they said.
And even then, engineering glaciers would only limit sea-level rise, while reducing emissions could also limit other harmful consequences of climate change, such as ocean acidification, floods, droughts and heat waves.
"The more carbon we emit, the less likely it becomes that the ice sheets will survive in the long term at anything close to their present volume," Wolovick added.
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