Arctic refreezing plan achieves positive results

Field tests show that pumping seawater into snow on top of Arctic sea ice thickens the ice sheet, providing a viable way to maintain ice cover through the summer.

A bold plan to pump seawater into the frozen Arctic Ocean could offer humanity its last chance to stop the region's sea ice from disappearing. A field trial this year in the Canadian Arctic to thicken sea ice using the seawater underneath was a success, according to British start-up Real Ice, New Scientist reported on September 23.

Seawater is pumped onto the snow on the ice surface to thicken the ice layer. (Photo: Real Ice).

Arctic sea ice is shrinking rapidly due to climate change. Many scientists predict the region will be ice-free in the summertime of the 2030s, even with immediate, drastic cuts in emissions. Now the only way to save the region's summer sea ice is to artificially thicken it.

Real Ice's solution involves drilling through the ice sheet to the ocean, then pumping water into the snow above the ice sheet . The water would flood pockets of air in the snow and freeze, turning the snow into ice. This would increase the ice shelf's thermal conductivity, meaning the cold air from the Arctic air would spread and encourage more ice to form on the underside of the ice sheet. "Our goal is to demonstrate that ice-thickening can be effective in maintaining and restoring Arctic sea ice ," said Andrea Ceccolini, a representative for Real Ice.

The approach was first proposed by University of Arizona researcher Steven Desch and colleagues in 2016. They estimated that deploying ice-thickening across 10% of the Arctic could reverse recent ice loss in the region.

Working with the Climate Restoration Centre at the University of Cambridge, Real Ice is conducting a field trial in Cambridge Bay on Victoria Island in Canada this year. The company says the experiment has validated the idea. A pilot borehole thickened the ice shelf by 50cm (20 inches) above a control site from January to May. The results showed that the technique pushed natural ice up by 25cm (10 inches) on the underside of the ice shelf, according to Shaun Fitzgerald, a researcher at the University of Cambridge. The experiment also demonstrated that the brine left over from the frozen seawater dripped through the ice pack back into the ocean, rather than remaining in the frozen layer on the top of the ice sheet, which threatens to weaken the structure and cause early summer melt.

When deployed on a large enough scale, the technique could extend the life of Arctic sea ice while humans cut emissions to combat climate change, Ceccolini said. It would also help maintain the albedo effect, in which intact ice reflects sunlight back into space, preventing the planet from warming further.

This year's experiment by Real Ice covers just an area of ​​ice the size of a football field. To make a meaningful impact, they'll need to treat thousands of square kilometers, requiring countless pumps and boreholes. To do that, Real Ice plans to develop an underwater drone that can travel across the Arctic, drilling cores through the ice at strategic locations to pump seawater into the ice sheet. The company has partnered with the Institute of Biorobotics at the Sant'Anna School of Advanced Studies in Pisa, Italy, to design the drone. They aim to have a prototype ready by 2025 and test it during the 2026-2027 Arctic winter.

One drone can process 2 ^square kilometers of ice per season. Initial calculations suggest that it would take 500,000 drones to create an additional 500 ^cubic kilometers of sea ice each winter over a total area of ​​1 million square kilometers ^. Deployment on this scale would cost about $6 billion a year, paid for by governments through the United Nations.

Real Ice will return to Cambridge Bay in November to conduct a large-scale experiment with five boreholes spread across a kilometre of sea ice. The company will confirm how much thicker the ice sheet can become by early winter.