The Arctic may continue to freeze every winter even as its permanent ice disappears. Understanding that apparent paradox requires looking beyond the North Pole to the seas between Norway, Svalbard, Iceland and Greenland—the great Nordic gateway through which Atlantic heat enters the Arctic Ocean.
The geography of the polar regions imposes formidable limits on how quickly their enormous stores of ice can disappear. Seasonal darkness, low solar radiation and the sheer volume of ice locked inside Greenland and Antarctica ensure that neither region will suddenly become ice-free. Yet this physical reality can easily be turned into a misleading reassurance. The fact that the Arctic Ocean will continue to freeze during winter does not mean that its present ice cover is secure. Nor is the Arctic sealed off from warmer waters arriving from lower latitudes. On the contrary, one of the most important routes carrying heat towards the North Pole runs directly through the Nordic region. Warm Atlantic water travels north between Iceland and Scotland, follows the Norwegian coast, crosses the Norwegian and Barents Seas and continues past Svalbard through Fram Strait. Farther west, colder water and drifting ice travel south along Greenland. The waters between Norway and Greenland are therefore not simply the Arctic’s frozen outer wall. They are a dynamic climatic crossroads: a place where Atlantic and polar waters meet, heat is exchanged with the atmosphere and the future of Arctic ice is being decided.
There is no single northern “polar ice cap”
Any discussion of polar melting must begin by distinguishing between sea ice and land ice. The ice covering much of the Arctic Ocean is frozen seawater. It grows during the dark winter and retreats when sunlight and warmer air return. Because it is already floating, its melting has little direct effect on global sea level—just as ice melting in a glass does not significantly raise the level of the drink. Greenland is different. Its ice sheet rests on land, covers approximately 1.7 million square kilometres and reaches a thickness of more than three kilometres in places. If it were eventually lost in its entirety, it would raise average global sea level by about seven metres. Greenland and Arctic sea ice therefore operate on radically different timescales. A large part of the Arctic Ocean could become practically ice-free at the end of summer within decades, while the complete disappearance of the Greenland Ice Sheet would require sustained warming over centuries or millennia. Calling both of them the “North Pole ice cap” obscures the most important part of the story.
Winter freezing is not the same as permanent ice
Every autumn, the Arctic enters months of darkness. Surface waters release heat, their temperature falls towards the freezing point and new sea ice begins to form. Some degree of winter freezing is expected to continue even in a considerably warmer climate. But that does not guarantee the survival of the thick, multi-year ice that once dominated much of the Arctic Ocean. Newly formed ice is generally thinner and more vulnerable to the following summer’s heat. If it melts before surviving a full summer, it never becomes multi-year ice. The Arctic can consequently refreeze every winter while its long-lived ice reservoir continues to contract. In 2025, Arctic winter sea ice reached the lowest annual maximum in the satellite record, according to NOAA. At the end of that summer, the ice cover was 28 per cent less extensive than in 2005, while the amount of multi-year ice had fallen sharply. Almost none of the oldest ice—more than four years old—remained. The remaining concentration of multi-year ice is found primarily north of Greenland and the Canadian Arctic Archipelago. Even this area, once regarded as a likely final refuge for Arctic sea ice, is undergoing significant change. The distinction is crucial. An Arctic Ocean that freezes in winter but becomes nearly ice-free in September is not climatically equivalent to the Arctic of the twentieth century.
The Atlantic road to Svalbard
The original image of the Arctic as an ocean protected from tropical heat by narrow gateways contains a grain of truth. The Bering Strait is shallow, while the Canadian Arctic Archipelago restricts exchanges with the North Atlantic. The Arctic Ocean is also surrounded by large continental landmasses that become intensely cold during winter. But Fram Strait and the Barents Sea do not prevent warm Atlantic water from entering the Arctic. They are its two principal Atlantic gateways. The journey begins much farther south. Water carried northwards by the wider Gulf Stream system crosses the Greenland–Scotland Ridge and enters the Nordic Seas. One branch continues along the Norwegian coast and towards the Barents Sea. Another becomes the West Spitsbergen Current, carrying comparatively warm and salty Atlantic water along the western side of Svalbard and through Fram Strait. The effect is visible in the geography of the archipelago. Western Spitsbergen is far more accessible and maritime than its extreme latitude might suggest. The sea around the west coast can remain navigable while waters at comparable latitudes elsewhere are covered by ice. This Atlantic inflow helps explain why Longyearbyen, at 78 degrees north, has a relatively moderated coastal climate—and why Svalbard is also one of the clearest observation points for the transformation now taking place.
What “Atlantification” means
Scientists use the term Atlantification to describe the increasing influence of warmer, saltier Atlantic water on the Arctic Ocean. Normally, much of that Atlantic heat lies beneath a colder, fresher surface layer. The difference in salinity creates a density barrier known as the halocline, limiting the upward movement of heat and helping sea ice survive. As Atlantic waters become warmer and the Arctic Ocean’s stratification weakens, more heat can mix upwards. That can delay autumn freeze-up, reduce winter ice growth and make the resulting ice more vulnerable during summer. The process is particularly advanced in the Barents Sea and the Eurasian sector of the Arctic. NOAA reported in 2025 that the signature of Atlantification had reached the central Arctic Ocean, far beyond the traditional Atlantic boundary. This is not simply a story about temperature. Changing ocean conditions can alter plankton communities, fish distribution, food webs and carbon cycles. Species associated with more temperate Atlantic waters can move northwards, while organisms adapted to ice-covered seas lose habitat. For Norway and Svalbard, Atlantification is simultaneously a climate story, a fisheries story and a geopolitical story.
Greenland: where the cold current travels south
If the eastern side of the Nordic gateway carries Atlantic heat north, its western side carries polar water and ice south. The East Greenland Current flows from Fram Strait along Greenland’s eastern coast, transporting cold, relatively fresh water and sea ice towards the Nordic Seas and the North Atlantic. This makes Fram Strait a two-way climatic passage: warm Atlantic water generally enters on the eastern side, while colder Arctic water and ice leave on the western side. Changes in this exchange can have consequences well beyond the Arctic. Freshwater entering the Nordic Seas influences the density of surface waters and their ability to sink—one component of the larger Atlantic overturning circulation that redistributes heat across the ocean. Greenland’s glaciers are also exposed to oceanic heat. Warm water can enter deep fjords and reach the submerged fronts of marine-terminating glaciers, melting them from below and encouraging the discharge of ice into the sea. The Greenland Ice Sheet will not disappear in a few decades. Its enormous volume gives it immense thermal and mechanical inertia. Nevertheless, “slow” in geological terms does not mean harmless in human terms. Greenland is already losing mass and contributing to sea-level rise. According to NOAA’s 2025 Arctic Report Card, Greenland lost an estimated 129 billion tonnes of ice during the 2024–25 mass-balance year. This was below its average annual loss since 2003, but it continued the long-term trend of net decline.
Svalbard’s glaciers tell a faster story
Between the seasonal sea ice of the Arctic Ocean and Greenland’s continental-scale ice sheet lie the smaller glaciers and ice caps of Svalbard and Arctic Scandinavia. These glaciers respond more rapidly to changes in air and ocean temperature. During the 2023–24 balance year, glaciers in Svalbard and Arctic Scandinavia experienced their largest annual net ice loss on record. Austfonna, in Nordaustlandet, is among the world’s largest ice caps outside Greenland and Antarctica. Research by the Norwegian Polar Institute has shown how ocean conditions can influence melting at its marine margins. It offers a particularly powerful Nordic example of the relationship between changing currents and land-based ice. Unlike floating sea ice, the loss of these glaciers contributes directly to rising seas. It also transforms landscapes, freshwater systems and ecosystems at a timescale that can be observed within a human lifetime.
Why geography still matters
None of this means that polar geography is irrelevant. The high latitude, winter darkness and reflective surface of snow and ice remain powerful cooling mechanisms. The Arctic Ocean’s restricted connections with other oceans also influence how heat, salt and freshwater circulate. Greenland acts as a vast physical barrier, while the Nordic Seas release considerable quantities of Atlantic heat to the atmosphere before the remaining water reaches the central Arctic. But these are controls and constraints—not “unbreakable” guarantees that the existing ice environment must persist. Sea ice also creates its own feedback. A bright ice-covered surface reflects much of the Sun’s energy. When that ice disappears, the darker ocean absorbs more heat, delaying the following freeze and reinforcing warming. Geography encourages winter ice formation, while climate feedbacks determine how thick that ice becomes and whether it survives the next summer.
The Arctic can freeze and still lose its ice
The most useful conclusion is also the most counter-intuitive: the Arctic can continue freezing every winter while steadily losing the ice that once defined it. Winter ice formation, summer sea-ice survival, glacier retreat and the long-term stability of the Greenland Ice Sheet are separate questions. They cannot be answered with a single claim about darkness or polar geography. The Nordic region sits at the centre of all four. Norwegian currents carry Atlantic heat north. Svalbard records the retreat of sea ice and glaciers. Greenland sends cold water and ice south while its land-based ice sheet loses mass. The Barents and Greenland Seas help regulate exchanges between the Atlantic and Arctic Oceans. The North Pole may be surrounded by continents, but it is not cut off from the rest of the planet. Its most important oceanic connection runs through the Nordic Seas—and that gateway is becoming warmer.
Suggested Online Sources
NOAA Arctic Report Card 2025 – Sea ice
NOAA Arctic Report Card 2025 – Atlantification of the Arctic Ocean
NOAA Arctic Report Card 2025 – Executive summary
NOAA Arctic Report Card 2025 – Sea-surface temperature
IPCC – Climate Change 2021, Chapter 12
NASA – Ice Sheets: Earth Indicator
NASA – New Greenland maps show more glaciers at risk
Norwegian Polar Institute – Austfonna research
