Marine heatwaves are becoming more frequent and intense. The Arctic Ocean also suffers from this development: The absence of sea ice will lead to more extreme fluctuations in ocean temperatures, with abrupt temperature changes occurring at unprecedented rates. A new study led by the Alfred Wegener Institute shows how marine heatwaves will also become much more intense and frequent in the Arctic in the 21st century. With drastic consequences for the ecosystem. The researchers published their findings in the scientific journal Nature Climate Change.
The Arctic Ocean is the only ocean basin with large areas of sea ice cover. Underneath the sea ice, temperatures are relatively constant, because it reflects the sunlight and thus largely prevents the ocean from warming up through the atmosphere. However, due to climate change and its consequences, the Arctic sea ice is retreating more and more. As a result, periods of abnormally high ocean temperatures are becoming more frequent and intense. These heatwaves and the associated environmental changes may be unprecedented for the modern climate. An international research team led by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) has now conducted a study to investigate how marine heatwaves in the Arctic could develop and impact the ecosystem in the future.
For the study, the researchers utilized high-resolution climate models that can project temperature changes of 0.1° Celsius in the ocean and 0.25° Celsius in the atmosphere. “Our predictions show that Arctic marine heatwaves will not only occur more frequently, but will also vary in intensity from year to year as the sea ice retreats,” says Ruijian Gou, visiting PhD student at the AWI and lead author of the study. These extreme fluctuations are expected to disrupt the region's ecosystems. “In our study, we highlight a crucial feedback mechanism: rising ocean temperatures,” says study leader Dr Gerrit Lohmann from the AWI. They enhanced stratification in the ocean because the warm surface water overlays the colder, denser water. “This disruption will lead to reduced nutrient mixing and threaten Arctic marine life, exacerbating the already challenging conditions faced by species dependent on stable habitats.”
Extreme temperature fluctuations and nutrient shortages could impact the whole ecosystem from plankton to top predators, potentially altering the structure of the Arctic food web. In order to better understand and predict these impacts, the researchers call for the development of integrated climate and biological models, that combine high-resolution climate simulations with physical and biological insights – which are currently lacking but urgently needed for more accurate projections. Without those, mitigating the effects of marine heatwaves and preserving Arctic ecosystems will become increasingly difficult.
Original publication
Ruijian Gou, Klara K. E. Wolf, Clara J. M. Hoppe, Lixin Wu, Gerrit Lohmann. The changing nature of future Arctic marine heatwaves and its potential impacts on the ecosystem. Nature Climate Change (2024). DOI: 10.1038/s41558-024-02224-7