North of Greenland, the Arctic Ocean and its projected Last Ice Area are shown in red. Canada's Tuvaijuittuq marine protected area is the purple cross-hatched section of the Last Ice Area. The Arctic countries' exclusive economic zones are delineated by black lines. Credit: Adapted by Newton et al. Earths Future 2021
The Arctic's summer sea ice has been shrinking rapidly due to warming. It now covers less than half of the area it covered in the 1980s. The question is: If this continues, will year-round seaiceand the creatures that depend on it for survival survive anywhere in the future?
This question is being addressed by a new study, which has some pretty scary results. The study focuses on a 1,000,000-square-kilometer area north of Greenland, along the coasts of Canada Archipelago. This is the region where the year-round sea-ice has been the thickest and most resilient. According to the study, this area's summer ice will be drastically reduced by 2050 under both optimistic as well as pessimistic scenarios. If carbon emissions are reduced by then, some summer-ice could last indefinitely under the optimistic scenario. If emissions continue to rise, however, then summer ice and creatures like seals or polar bears would be extinct by 2100. The study is published in Earth's Future.
Robert Newton, senior research scientist at Columbia University’s Lamont-Doherty Earth Observatory, said, "Unfortunately this is a huge experiment we're performing." "If year-round ice disappears, ecosystems that depend on it will be destroyed and something new will start."
For decades, scientists have been wondering about the fate of Arctic sea-ice. Researchers including Newton's coauthors Stephanie Pfirman, L. Bruno Tremblay and L. Bruno Tremblay came together around 2009 to discuss the concept of the Last Ice Area. This is the region where summer ice could make its last stand.
The Arctic Ocean's surface freezes in winter. This will continue to be true for many years, even though the climate is warming. Each winter, ice can grow up to one meter thick, and, if it survives one summer, can reach several meters. Summer is characterized by some melting and the appearance of open-water zones. Winds and currents help transport floating ice long distances in many gyres. This includes the Transpolar Drift which transports ice clockwise from Siberia to Greenland and Canada. Some ice is ejected into the North Atlantic each year via the Straits between Greenland & Norway. Much of this ice is driven towards the Arctic's northernmost coasts, Greenland and the Canadian Islands. Repeated inflows can create layers and pressure ridges up to 10 meters high. It will often remain for ten years or longer before moving away.
This has created a rich marine ecosystem. Photosynthetic diatoms grow along the edges and bottoms, and they build thick mats over time. These tiny animals live in and around the ice and feed fish, seals, and polar bears. The thick and irregular topography offers plenty of hiding spots for seal lairs and ice caves where polar bears can winter over and rear their young. It provides safe refuge from the humans who cannot navigate it even with icebreakers.
Sea ice north from the Canadian Arctic Archipelago. This photo was taken by an icebreaker from just outside the Last Ice Area. It is nearly impossible for ships to navigate this area. Credit: Robert Newton/Lamont-Doherty Earth Observatory
The majority of the ice that ends in the Last Ice Area was formed over the Transpolar drift and has been sourced from the continental shelves near Siberia. Siberian ice can also mix with ice from the central Arctic Ocean that may also travel to the Last Ice Area. The ocean is now producing thinner ice that melts faster in the summer's more open waters. Researchers predict that this trend will lead to the destruction of the Last Ice Area over the next few decades. While some ice will drift in from the central Arctic and some will form locally over time, neither will be sufficient to maintain current conditions.
Under the low-emissions scenario of the researchers, even the ice from central Arctic will begin to wane by mid-century. Thick, multiyear ice that is thick and heavy will disappear. However, locally formed summer ice, which will still exist in the Last Ice Area, will only be a meter thick. Good news is that some seals, bears, and other creatures may be able to survive in similar summer conditions as those found along the western coast of Alaska and parts Hudson Bay. Unfortunately, the worse news is that even locally-formed ice will disappear in summer under the higher emissions scenario. There will be no summer ice in any place, and no ice-dependent ecosystems.
Newton said, "This does not mean it will be a barren and lifeless environment." It may take time before new species emerge. "New things will arise, but it may take a while for them to infiltrate." Although fish, diatoms and other biota might be found in the North Atlantic, it isn't clear if they can survive year-round. The planet's rotation around its sun won't change so any new occupants, including photosynthetic organisms, would have to contend with the harsh Arctic winter.
A little bit of open water at the Last Ice Area's outskirts; behind it, the U.S. Ice Breaker Healy. Credit: Robert Newton/Lamont-Doherty Earth Observatory
Researchers see the positive side. Newton believes that the world could make enough progress in reducing carbon dioxide levels by the 21st Century to allow the region to survive long enough to see temperatures drop again and the Last Ice Area may start to re-grow. One encouraging sign is the 2019 establishment by Canada of the 320,000-square-kilometer Tuvaijuittuq marine protected area in Nunavut's Inuit territory. This covers the middle third of Last Ice Area. Canada is considering permanent protection, while this protects against mining and transport for five years. Rest of the area is located in Canada's mining-friendly Northwest Territories. Canada has so far resisted declaring protection and Greenland has so far not been committed.
Researchers say that if the Arctic's last ice area is to survive, it will be necessary to create marine protected zones. Because the Arctic Ocean and its coastlines contain billions of dollars worth of oil reserves and mineral deposits like nickel and copper, this is necessary. There will be more pressure to drill, dig and open transport corridors as summer waters open up. This could lead to pollution being exported to the last ice zone, not ice. Rosneft, a Russian oil company, already has leases in some areas that have traditionally fed ice to The Last Ice Area.
Researchers write that "Spilled Oil and Industrial or Agricultural Contaminants have been identified as potential hazards."
Stephanie Pfirman is the coauthor. She was previously with Lamont-Doherty. L. Bruno Tremblay works at McGill University. Patricia DeRepentigny is the study's second coauthor.
Explore more Last ice-covered Arctic Ocean parts that are vulnerable to climate change
More information: Robert Newton and others, Defining The "Ice Shed” of the Arctic Ocean’s Last Ice Area, Earth’s Future (2021). Robert Newton and colleagues, Defining The "Ice Shed” of the Arctic Ocean's Last Ice Area, and Its Future Evolution (2021). DOI: 10.1029/2021EF001988
