Understanding Regional and Seasonal Variability Is Key to Gaining a Pan-Arctic Perspective on Arctic Ocean Freshening

• Published in: Frontiers in Marine Science
• Main Authors: Kristina A. Brown, Johnna M. Holding, Eddy C. Carmack
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2020
• Subjects: Arctic Ocean; freshwater; freshening; primary production; stratification; physics; Science; Q; General. Including nature conservation; geographical distribution; QH1-199.5; Arctic; Pacific; Sea ice
• Online Access: https://doi.org/10.3389/fmars.2020.00606; https://doaj.org/article/01bdb661d26f41c68467e5890cd3cb20

The Arctic marine system is large and heterogeneous, harsh and remote, and now changing very rapidly, all of which contribute to our current inadequate understanding of its basic structures and functions. In particular, many key processes within and external to the Arctic Ocean are intrinsically linked to its freshwater system, which itself is undergoing rapid and uncertain change. The role of the freshwater system (delivery, disposition, storage, and export) in the Arctic Ocean has recently received significant attention; however, due to the fact that few studies are able to cover all regions and seasons equally, we still lack an accessible, unified pan-Arctic representation generalizing the impacts of freshwater on the upper Arctic Ocean where many biological and geochemical interactions occur. This work seeks to distill our current understanding of the Arctic freshwater system, and its impacts, into conceptual diagrams which we use as a basis to speculate on the impact of future changes. We conclude that an understanding of regional and seasonal variability is required in order to gain a pan-Arctic perspective on the physical-geochemical-biological state of the upper Arctic Ocean. As an example of regionality, enhanced stratification due to freshening will be more important in the Pacific influenced Amerasian Basin, which stores the bulk of the freshwater burden, while the Atlantic influenced Eurasian Basin will experience more consequences related to increased heating from advective sources. River influenced coastal regions will experience a mosaic of these and other biogeochemical effects, whereas glacial fjords may follow their own unique trajectories due to the loss of upwelling mechanisms at glacial fronts. As an example of seasonality, the continued modulation of the sea ice freeze-melt cycle has increased the seasonal freshwater burden in the deep basins dramatically as the system progresses toward ice-free summer conditions, but will eventually reverse, reducing the seasonal flux of freshwater by more ...