Scientists have successfully tested a method that could help slow the melting of Arctic sea ice by pumping seawater onto existing ice during winter and allowing it to freeze into an additional layer. The field experiment, conducted in Cambridge Bay in Nunavut, Canada, during the winter of 2024-25, found that the treated ice became thicker and more reflective than untreated ice, making it more resistant to summer melting.

The findings, published on May 22 in the journal Earth's Future, suggest the technique could eventually help Arctic communities cope with shrinking sea ice. However, researchers cautioned that significantly more research is needed before the method can be considered for large-scale deployment.

Simpler approach than other geoengineering proposals

Researchers said sea ice thickening is a relatively simple approach compared with more controversial geoengineering proposals such as stratospheric aerosol injection, which involves releasing sulphur particles into the atmosphere to reflect sunlight and has raised concerns over possible environmental impacts.

The study noted that Nordic and Arctic communities have used similar ice-thickening techniques for decades, while the same principle is commonly applied in maintaining ice hockey rinks. Earlier computer modelling also suggested thicker sea ice could reduce coastal erosion, improve travel conditions and support animal migration and hunting.

Field experiment showed significant increase in ice thickness

The research team established eight treatment sites and three untreated control sites in Cambridge Bay. Using submersible pumps that each consumed less electricity than a household toaster, they sprayed up to 20 centimetres of seawater onto the treatment areas either once or twice. The control sites were left unchanged.

One control site was later used for a separate melt pond drainage experiment, during which researchers drilled small holes to remove meltwater and expose the brighter ice beneath the surface.

By the end of winter, the treated ice had become up to 32 centimetres thicker than the untreated ice, roughly matching the amount of Arctic sea ice thinning recorded over the past 50 years. Areas treated twice also developed thicker ice than those flooded only once.

From late May through September, the treated ice remained brighter, melted more slowly and retained greater thickness than the untreated control sites.

Why the technique works

Researchers explained that pumped seawater mixes with the snow covering the sea ice and freezes into a fresh ice layer. At the same time, the reduced snow cover decreases insulation, allowing colder air temperatures to accelerate natural ice growth from below.

Thicker ice also reflects more sunlight back into space instead of absorbing it, helping keep the region cooler. If similar results can eventually be achieved over much larger areas, the increased reflectivity could contribute to regional cooling while also helping slow permafrost thaw and reduce Greenland ice loss.

Large-scale deployment remains a major challenge

Despite the encouraging results, researchers said expanding the technique across the Arctic would be extremely difficult.

A 2016 study estimated that about 10 million wind-powered pumps would be required to treat just 10% of the Arctic Ocean, while covering the entire region would need around 100 million pumps.

The study noted that Arctic sea ice has already declined by about 20% since 1979 and continues to shrink as global temperatures rise. A separate 2021 study said that if sea ice thickening is ever adopted on a large scale, deployment would have to occur quickly while sufficient sea ice remains.

A review published last year concluded that governance issues, maintenance demands and the enormous scale required make sea ice thickening impractical for meaningful Arctic-wide protection. However, researchers said more recent winter trials have continued to produce encouraging results.

(With inputs from TOI)