Freshwater in the Arctic Ocean 2010–2019

• Main Authors: Solomon, Amy, Heuzé, Céline, Rabe, Benjamin, Bacon, Sheldon, Bertino, Laurent, Heimbach, Patrick, Inoue, Jun, Iovino, Doroteaciro, Mottram, Ruth, Zhang, Xiangdong, Aksenov, Yevgeny, McAdam, Ronan, Nguyen, An, Raj, Roshin P., Tang, Han
• Format: Text
• Language: English
• Published: 2020
• Subjects: Arctic; Arctic Ocean; Greenland; Ice Sheet; Sea ice
• Online Access: https://doi.org/10.5194/os-2020-113; https://os.copernicus.org/preprints/os-2020-113/

The Arctic climate system is rapidly transitioning into a new regime with a reduction in the extent of sea ice, enhanced mixing in the ocean and atmosphere, and thus enhanced coupling within the ocean-ice-atmosphere system; these physical changes are leading to ecosystem changes in the Arctic Ocean. In this review paper, we assess one of the critically important aspects of this new regime, the variability of Arctic freshwater, which plays a fundamental role in the Arctic climate system by impacting ocean stratification and sea ice formation. Liquid and solid freshwater exports also affect the global climate system, notably by impacting the global ocean overturning circulation. In this review paper we assess to what extent observations during the 2010–2019 period are sufficient to estimate the Arctic freshwater budget with greater certainty than previous assessments and how this budget has changed relative to the 2000–2010 period. We include discussions of processes not included in previous assessments, such as run off from the Greenland Ice Sheet, the role of snow on sea ice, and vertical redistribution. We show that the trend in Arctic freshwater in the 2010s has stabilized relative to the 2000s due to an increased compensation between a freshening of the Beaufort Gyre and a reduction in freshwater in the Amerasian and Eurasian basins. Notably, the sea ice cover has become more seasonal and more mobile, the mass loss of the Greenland ice sheet has shifted from the western to the eastern part, and the import of subpolar waters into the Arctic has increased.