Intensification of Arctic Ocean eddy activity under global warming

Small-scale swirling motions about 100 km in size in the mid-latitudes are called “mesoscale eddies”. They are ubiquitous in the global ocean and play a critical role for the climate and marine ecosystems. In the Arctic Ocean, however, eddies are notably smaller than those observed in lower latitudes, posing a challenge even for current high-resolution climate models to accurately represent them. Given that the Arctic is experiencing profound climate change, it is essential to enhance research efforts and to advance the understanding of how Arctic eddy activity will evolve in a warming world, as the current knowledge in this area is limited.

The new study, published in the journal Nature Climate Change, shows how Arctic Ocean eddy activity could develop in the 21st century: The researchers employed a new-generation ice-ocean model with a horizontal resolution of one kilometer and found out that Arctic eddy activity will be intensified by a factor of at least three in a four-degree warmer world. Surprisingly, this level of intensification surpasses that of eddy-rich regions elsewhere in the global ocean.

A remarkable transformation at the Arctic Ocean surface is shown in the research: Transitioning from an "eddy desert" directly beneath sea ice to a dominance of eddies in large ice-free regions in the future. "Our results suggest that the Arctic Ocean will experience much more energetic eddy variability due to climate change,” notes Xinyue Li, first author of the publication and a PhD student at the AWI.

This change is expected to lead to intensified eddy transports of heat, carbon, oxygen, and nutrients, which could reshape the Arctic's role in climate and marine ecosystems. For that reason, enhancing current climate models to accurately represent Arctic Ocean eddy activity is imperative. “Our current knowledge about future climate change is mainly based on projections of climate models, which do not fully incorporate the effects of eddies. Our results suggest that some of our understanding about future Arctic climate change may need to be revisited by using kilometer-scale climate model simulations,” says Dr. Qiang Wang, principal investigator of the research project and scientist at the AWI.