Can rebuilding the ice sheet slow global warming

The essentials

The company Real Ice is testing a method in Canada designed to refreeze the surface of sea ice, slow summer melt and improve Earth’s albedo.

At full scale, the project imagines using hundreds of thousands of underwater drones to thicken Arctic ice and help limit global warming.

Many scientists remain skeptical. Their concerns focus on effectiveness, environmental risks, cost, governance and the danger of treating symptoms rather than the root cause of climate change.

February 2025, Canadian Far North. A haze of ice crystals hangs in the air, forming a halo around the low Sun as three snowmobiles move across the sea ice. It was –26°C when we left Cambridge Bay, an Inuit village in a vast archipelago of treeless islands and ice-filled channels. For the season, that was still relatively mild: about six degrees above average.

The winter had been unusually warm, and the Arctic was already sending warning signals. NASA and the National Snow and Ice Data Center reported that Arctic winter sea ice reached its lowest annual maximum in the satellite record on March 22, 2025, covering 14.33 million square kilometers, or 5.53 million square miles. That was below the previous record low set in 2017.

The British company Real Ice hopes to respond to this loss with a project that some describe as visionary, others as unrealistic, and others still as dangerous. Its idea is simple in principle: during the coldest months, drill through the sea ice, pump seawater onto the surface, let it freeze, and build a thicker layer that may survive longer into summer.

Seven kilometers from the village, Real Ice co-founder Cían Sherwin, an Irish entrepreneur wearing a red hat and a goatee, jumps off his snowmobile and starts drilling into the ice with a long electric auger. Water and frozen chips spray from the hole as the tool reaches the seawater below, about 1 meter under the surface. Inuit guide David Kavanna widens the opening with a spear-shaped saw and places a wooden crate nearby. Sherwin lowers an aluminum pump into the water. A curved pipe rises from it. Once the pump is connected to a battery, pale blue water begins flowing over the ice. “The water behaves almost like lava,” he observes. “The ice forms almost instantly.”

Why sea ice matters so much

In winter, when the Arctic is cold and dark, sea ice grows across the ocean. In summer, when the Sun shines almost continuously, part of it melts. That seasonal rhythm matters because sea ice reflects sunlight back into space, while darker open ocean absorbs much more solar energy. NSIDC describes Arctic sea ice as a kind of planetary air conditioner because its bright surface reflects sunlight and helps keep the region cooler.

NOAA also emphasizes that sea ice is not just a frozen surface. It is an interface between the ocean and atmosphere, a physical barrier that affects heat, moisture, salinity, ecosystems and Indigenous communities. Its decline allows darker ocean water to absorb more solar energy, reinforcing warming.

This is the logic behind Real Ice’s approach. If sea ice can be made thicker in winter, perhaps more of it can survive through summer. Real Ice calls its method “AquaFreezing” and says it is designed to enhance the natural sea-ice formation process using pumps, renewable energy and simple devices. The company says its long-term concept would combine water pumps, hydrogen fuel cells and autonomous underwater vehicles.

The scale, however, is enormous. Scientific American reported that Real Ice thickened about 250,000 square meters of sea ice during one winter and hopes to test a 100-square-kilometer demonstration in the winter of 2027–2028. The company’s larger vision would eventually target about one million square kilometers of Arctic sea ice, requiring roughly 500,000 underwater drones.

A controversial form of climate intervention

The project belongs to a broader and controversial category often called polar geoengineering. These are large-scale interventions aimed at slowing or masking some effects of global warming in polar regions. In this case, the intervention would not remove carbon dioxide from the atmosphere. It would try to preserve the reflective surface of sea ice for longer.

Supporters argue that the Arctic is warming so quickly that research into emergency tools is justified. Ocean Visions notes that Arctic summer sea ice has declined by at least 50% over the last four decades and that thicker multi-year ice at least five years old has decreased sharply since 1979. The organization also states that the only permanent way to stop Arctic sea ice loss is to reduce global temperatures through deep greenhouse gas cuts and carbon removal.

Critics see the problem differently. A Frontiers in Science assessment summarized by the journal’s explainer argues that polar geoengineering proposals, including sea ice management, face major questions of feasibility, environmental impact, governance, cost and scale. The authors conclude that none of the five evaluated approaches currently stands up as workable over the coming decades.

The governance issue is especially sensitive in the Arctic. Sea ice moves across national boundaries, and any large-scale intervention would require cooperation between Arctic states, Indigenous communities and local residents. The Frontiers explainer stresses that the Arctic is divided across several jurisdictions and that Indigenous communities would need to be involved in decisions about consequences and risks.

The real question: solution or distraction?

The strongest criticism is not only technical. It is political and ethical. Opponents worry that projects like this could create the impression that the climate crisis can be managed without cutting fossil fuel emissions fast enough.

That concern is central to the debate. The Frontiers assessment warns that geoengineering may create false hope and divert attention and money from proven solutions, especially rapid emissions reductions. Its authors argue that decarbonization should remain the priority for protecting polar regions.

Real Ice, for its part, presents its work as research, not as a replacement for climate action. The company says it aims to protect local and global communities from the effects of a warming Arctic and to work with local communities affected by environmental change.

For now, the honest answer is cautious: rebuilding sea ice might help scientists better understand whether targeted ice thickening can preserve small areas for longer. But there is no official scientific consensus showing that it can be scaled safely, affordably and effectively across the Arctic.

What is clear is that Arctic sea ice remains one of the most visible warning signs of climate change. It influences ecosystems, local livelihoods and the global climate system. Even if experimental approaches like Real Ice continue, the main lever remains the same: reduce greenhouse gas emissions quickly enough to limit further warming.

So, can rebuilding sea ice slow global warming? Perhaps locally, experimentally and temporarily, if the method works as planned. But based on current evidence, it cannot be treated as a substitute for cutting emissions. At best, it is a risky and still unproven complement. At worst, it could become an expensive distraction from the hard work the planet already knows it must do.