Arctic Experiment Shows Promise for Thickening Sea Ice

A field experiment in Cambridge Bay, Nunavut, has demonstrated that pumping seawater onto existing winter ice can significantly increase its thickness and brightness, offering a potential strategy to combat Arctic ice loss.

The Experiment

The study, published on May 22 in Earth's Future, tested a straightforward technique during the winter of 2024–2025. Researchers established eight test areas and three control sites on the Arctic ice.

Submersible pumps, each consuming less power than a toaster, were used to flood test areas once or twice with up to 20 cm of seawater. The control sites were left untouched. In an additional experiment at one control site, researchers drilled small holes to drain meltwater, exposing brighter ice underneath.

Key Results

By the end of winter, the test areas had grown up to 32 cm thicker than the control sites — a figure roughly equal to the total Arctic ice thinning observed over the past 50 years.

• Areas that were flooded twice showed greater thickening than those flooded only once.
• During the melt period (late May to September), the ice in test areas appeared brighter and melted more slowly, remaining thicker than the control ice.
• The melt pond drainage site also produced noticeably brighter ice.

How It Works

Pumping seawater onto sea ice saturates the overlying snow. The snow-water mixture freezes into a new ice layer.

The mechanism reduces the insulating effect of snow, according to study co-authors Edward Blanchard-Wrigglesworth and Andrea Ceccolini. With less insulation, colder air temperatures can accelerate ice growth from below, leading to a thicker, more reflective surface.

Broader Implications

Thicker, brighter sea ice reflects more sunlight back into space. The authors stated that if the method could be scaled, increased Arctic albedo could contribute to regional cooling, potentially slowing permafrost thaw and reducing ice loss from the Greenland ice sheet.

Scalability Concerns

Despite the promising results, significant hurdles remain:

• A 2016 study estimated that 10 million wind-powered pumps would be needed to cover just 10% of the Arctic Ocean, and 100 million pumps for the entire Arctic, raising serious questions about financial and logistical feasibility.
• Arctic sea ice extent has shrunk by 20% since 1979, with losses accelerating. A 2021 study warned that for large-scale deployment, pumps must be deployed immediately while sufficient ice remains.
• A 2023 review concluded that sea ice thickening is not feasible at a meaningful scale due to ecological, social, governance, and maintenance challenges.

Ongoing Research

Blanchard-Wrigglesworth and Ceccolini reported that recent winter trials (not yet published) showed test areas growing 50 cm thicker than controls — a significant improvement over the published results.

The team is developing underwater robotic technology for autonomous deployment and has conducted the first Arctic tests of a prototype re-icing drone in Finland, in collaboration with the BioRobotics Institute in Pisa, Italy.