Melting sea ice on Franklin Starait (AP file photo)
Scientists have tested an idea that could help limit the melting of Arctic sea ice, and initial results are promising. The method involves spraying seawater onto existing sea ice in winter and letting it freeze into a new layer.The field trial was conducted in Cambridge Bay in Nunavut, Canada, during the winter of 2024-2025. The scientists also found that the treated ice was thicker and more reflective than untreated ice. This makes it more resilient against summer thaw.The results, published May 22 in the journal Earth’s Future, suggest that this method could one day help Arctic communities cope with shrinking sea ice. However, the researchers also say that more work is needed before its wider use can be considered.
An alternative to controversial geoengineering
Scientists are exploring several ways to slow the rapid loss of Arctic sea ice. Some proposed geoengineering methods, such as stratospheric aerosol injection, involve releasing tiny sulfur particles into the atmosphere to reflect sunlight away from Earth. The idea has become controversial because of its potential environmental impacts.Sea ice thickness is much simpler and not new. According to the researchers, Nordic and Arctic societies have used similar methods for decades.
Ice hockey rinks also rely on the same basic principle to keep the ice strong.Previous computer models have also suggested that thicker sea ice could help reduce coastal erosion near Arctic cities, make travel easier and support animal migration and hunting.
How was the experiment carried out?
The researchers set up eight test areas and three monitoring sites in Cambridge Bay, Canada. Using submersible pumps that each consume less electricity than a home toaster, they pumped up to 20 cm of seawater into the test areas either once or twice.
Control sites were left unchanged.Later, one of the monitoring sites was used for a separate melt pond drainage experiment. The researchers drilled small holes to drain the meltwater from the surface and expose the brighter ice underneath.By the end of winter, the treated areas were up to 32 cm thicker than the untreated areas. According to the study, this is roughly equivalent to the amount of Arctic sea ice melt recorded over the past 50 years.
Areas that were flooded twice also became denser than those that were flooded only once.During the melt season between late May and September, treated ice also remained brighter, melted more slowly, and remained thicker than ice at control sites.
Why pumping seawater makes ice stronger
When seawater is pumped onto sea ice, it mixes with the ice covering the surface. The mixture of water and snow freezes to form a new layer of ice, while the reduced snow insulation allows cold atmospheric temperatures to accelerate the growth of natural ice from below.Thick ice is generally brighter than thin ice. A brighter surface reflects more sunlight into the space rather than absorbing it, which helps keep the area cool.If similar results can eventually be achieved over much larger areas, increased reflectivity could contribute to regional cooling. It could also help slow the melting of permafrost and reduce ice loss from Greenland.
Could this work across the Arctic?
While early results are promising, researchers acknowledge that expanding this technology across the Arctic will be extremely difficult.A 2016 study estimated that about 10 million wind-powered pumps would be needed to treat just 10% of the Arctic Ocean. Covering the entire Arctic would require about 100 million pumps.Arctic sea ice has already shrunk by about 20% since 1979, and the decline continues as global temperatures rise. A 2021 study suggested that if sea ice thickening were to be used on a large scale, pumps would need to be deployed quickly while there was still enough sea ice left.A review published last year concluded that because of management challenges, maintenance requirements and enormous scale, sea ice thickness is simply not amenable to use at a scale and rate that could be useful for sea ice protection. However, recent winter trials have produced encouraging results.