On Monday this week, the researchers from the Norwegian Polar Institute came ashore after a more than three-week long research trip in the inner Arctic Ocean. The next day, they presented new research in the renowned journal Nature Communications. In the coming decades, the Arctic Ocean will change dramatically from a calm, ice-covered sea to a more open sea with stronger ocean currents. This will have consequences for the ecosystems in the Arctic – and the global climate. The researchers spent 3.5 weeks in the Arctic Ocean this summer. Photo: Trine Lise Sviggun Helgerud, Norwegian Polar Institute – The Arctic Ocean as we know it today will look very different, both ten years from now and at the end of the century. This is what climate researcher at the Norwegian Polar Institute Morven Muilwijk tells news. He adds: – There will of course be much less ice and more open water. But the animals that live there will also be affected, and will have a completely different ecosystem to live in. Will measure change over time From the research ship “Kronprins Haakon”, climate scientists from the Norwegian Polar Institute and Germany’s GEOMAR, led by Muilwijk, have measured the ocean currents under ice sheets, for to map the state of the Arctic Ocean. It is here, in the Arctic, that the effect of climate change will be greatest, the researchers believe. Trine Lise Sviggum Helgerud / Norwegian Polar Institute Today’s condition will act as a reference for measuring changes. With the help of climate models, which are used in the UN climate panel’s sixth main report, the researchers have made forecasts for how the wind and ocean currents will be very different in a few years. – The models show that as the Arctic Ocean continues to warm up due to global warming, wind speeds will increase and the sea ice will decrease, says Muilwijk. Professor of marine ecology at UiT – Norway’s Arctic University, Marit Reigstad, has no doubt that the importance of increased knowledge about ecology in the Arctic Ocean. – In general, we have very little knowledge about life in the Arctic Ocean, but know that a lot will change. Such work as this is very important. It is also important to work with models, and that they are as good as possible, so that we can be better prepared for what awaits us in the future, she says. Morven Muilwijk, climate researcher at the Norwegian Polar Institute. Photo: Trine Lise Sviggum Helgerud, Norwegian Polar Institute The ice acts as a lid Today, the sea ice in the Arctic acts as a stable lid, which for large parts of the year shields the water masses from being directly affected by the wind. Beneath the ice, the Arctic Ocean has a clear layering. At the top floats a layer of cold polar water. Further down in the depths lies salty, warm Atlantic water. When the ice shrinks, the sea will become more exposed to wind. This leads to more energy being transferred from the atmosphere to the ocean, rather than being absorbed in the ice. Trine Lise Sviggum Helgerud / Norwegian Polar Institute – When the ice cover becomes thinner and moves more, the ice absorbs much less wind energy. The wind energy is thus transferred more directly through the ice to the sea, says the climate scientist. This will strengthen the ocean currents at the surface. Eventually, it will also lead to movement further down in the water bodies, which will disrupt the current layering. – The warm water will mix upwards from the depths, and can contribute to melting the sea ice from below. This in turn reinforces the already ongoing climate changes, explains Muilwijk. – The entire ecosystem in the Arctic will change as a result of the strengthening of ocean currents, says the researcher. – It has long been known that the ice is disappearing. Are these new research findings cause for increased concern? – We have known for a long time that things happen, but we now know much more about the consequences. And our new study has dug a little deeper into what the big changes will be. – There will be a change According to the recent study, there could be 38 per cent more wind impact on the sea surface by the end of the century. Some models suggest an increase of up to 72 percent. Muilwijk emphasizes that there is always some uncertainty around future forecasts and climate modelling. – But we are sure that the results are robust and that there will be a change. The big question is how strong the change will be, and whether it will have consequences that we don’t know about yet. The changes in the layering will affect life in the sea, the researchers believe. The researchers have mapped the current state of the Arctic Ocean, so that they can monitor future developments. Photo: Trine Lise Sviggum Helgerud, Norwegian Polar Institute Consequences for life in the sea Today’s ocean layer controls how nutrients are distributed in the water. When these mix, nutrients from the depths will swirl upwards and also become available to phytoplankton that live in the top 50 meters of the water. – It will probably lead to more growth of phytoplankton, and that will have ripple effects for the entire ecosystem, says Muilwijk. – What kind of knock-on effects can it have? – We need more research to understand how the ecosystem changes, but we believe that more phytoplankton makes it easier to get more life in the Arctic Ocean. This will lead to more food available for zooplankton and fish, which in turn will affect the food chains all the way up to seals and polar bears. Professor in marine ecology, Marit Reigstad. Photo: UIT Apart from good conditions in early spring, as a result of increased ice melting in the Arctic, it is not certain that the consequences of algae growth will be so dramatic, says Professor Marit Reigstad. This is because the algae, like other plants, need light to grow and the period of darkness sets natural limitations. – There will probably be more algae growth, and it may come earlier than before with less ice. When the supply is exhausted, it will be limited unless there are very much stronger winds and mixing also in the summer months. She points out that the greatest mixing will, as indicated in the research, occur in autumn and winter. This is a time when it is dark in the northernmost areas, and thus poor conditions for algae growth. For species that are in the polar basin, or transported north by ocean currents, the change can be positive. This as these species will receive more nutrition and a longer growing season, the professor believes. – I don’t think we will get any large fisheries in the deep polar basin, but in the shallower shelf areas there may be more food and more fish than there is today, she says. Published 13.08.2024, at 21.45
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