How do you stop a glacier from melting? Put up an underwater curtain

This story was originally published by The Guardian and appears here as part of the Climate Desk collaboration.

Scientists are working on an unusual plan to prevent Antarctic glaciers from melting. They want to build a set of giant underwater curtains in front of ice sheets to protect them from being eroded by warm seawater.

Ice in polar regions is now disappearing at record rates as global warming intensifies, and urgent action is needed to slow down this loss, the international group of ­scientists has warned.

Their proposed solution is the construction of a 100-kilometre-long curtain that would be moored to the bed of the Amundsen Sea. It would rise by about 200 metres from the ocean floor and would partially restrict the inflow of relatively warm water that laps at the bases of coastal Antarctic glaciers and undermines them.

The Seabed Curtain Project, if implemented, would be one of the biggest geo-engineering programs ever undertaken. “It would be a giant project — but then we face a gigantic problem,” glaciologist John Moore of Lapland University told the Observer.

“The melting of glaciers in Antarctica could trigger catastrophic flooding around the planet and result in hundreds of millions of people losing their homes. That will be incredibly bad for civilization as we know it, so we need to do something.”

The curtain proposed by Moore — who is working with scientists at the University of Cambridge and other ­centres in the U.S. — would stretch along the seabed opposite the Thwaites and Pine Island glaciers. These act as plugs that prevent the giant ice sheets behind them from sliding into the ocean.

Scientists warn that the loss of the Thwaites and Pine Island glaciers could be enough to raise sea levels around the world by three metres if they melted, a prospect now considered to be a real threat as global warming takes a grip on the region and causes sea temperatures to rise.

“Glaciers are affected by warmer air which melts their surfaces but they are also eroded at their bases by warm seawater,” said Shaun Fitzgerald, director of the Centre for Climate Repair at the University of Cambridge, one of the partners in the scheme. “And as the oceans warm as the planet heats up due to climate change, the more intense is the erosion of ice at the bases of these glaciers.”

Building a curtain that restricts the flow of warm water on the Antarctic coast could slow the undermining of these glaciers and reduce the risk of their catastrophic disappearance, say the scientists. They envisage building a series of seabed curtains and are set to begin research to pinpoint the best materials for their construction.

“We are not going to do this with a single sheet of fabric and we are not looking at a perfect, sealing membrane,” added Fitzgerald.

One idea would be to use air as a barrier for protecting glaciers. A pipe — with holes drilled along it — would be laid down along the seabed and have air pumped through it. The curtain of air bubbles that would rise from it might then be able to hold back the ingress of warm seawater.

“We don’t know if that will work since we are only at a very early stage in our work,” added Fitzgerald.

“We need to study how salinity affects water flow and carry out all sorts of computer simulations and the testing of mathematical models. Then we will be ready for the first physical tests.”

These tests are to be carried out on the River Cam later this year when various models will be tested underwater.

“After that, we will begin to work on a bigger scale,” added Moore. “We might go to a fjord in Norway to build a prototype, for example.

“Certainly, this is not going to be something that will be completed in a hurry. It will take many years. On the other hand, we do need to start planning now.”