A groundbreaking study has presented the first observational proof of the stabilization of the anti-cyclonic Beaufort Gyre, which is the primary circulation pattern in the Canada Basin and serves as the largest freshwater reservoir in the Arctic Ocean.
The research utilizes an extended dataset of satellite-based “dynamic ocean topography” from 2011 to 2019, generously provided by two of the co-authors. This data, coupled with a comprehensive hydrographic dataset spanning 2003 to 2019, allows for a quantitative analysis of the gyre’s changing sea surface height in recent years.
Previous studies, based on earlier dynamic ocean topography data up until 2014, have already demonstrated that the gyre has strengthened and increased its freshwater content by a staggering 40% when compared to climatological records from the 1970s. The stabilization of the gyre may serve as a precursor to a massive freshwater release, which could have significant implications, including potential effects on the Atlantic Meridional Overturning Circulation (AMOC), a crucial component of global climate dynamics.
The Beaufort Gyre has now “transitioned to a quasi-stable state,” wherein the rate of sea surface height increase has decelerated, and the freshwater content has reached a plateau. Additionally, the cold halocline layer, responsible for isolating the warm and salty Atlantic water at depth, has substantially thinned. This can be attributed to reduced inflow of cold and salty water from the Pacific Ocean and the Chukchi Sea shelf, as well as increased entrainment of lighter water from the eastern Beaufort Sea. The recent shift in the location of the Beaufort Gyre towards the southeast is a result of variations in regional wind forcing.
The publication, titled “Recent state transition of the Arctic Ocean’s Beaufort Gyre,” appears in the esteemed journal Nature Geoscience.
The article suggests that the ongoing thinning of the cold halocline layer may influence the current stable state, potentially allowing for a release of freshwater. Such a release could lead to a freshening of the subpolar North Atlantic, which would have repercussions on the AMOC.
Given the multitude of possible local and remote effects on the hydrographic structure, physical processes, and ecosystem of the Arctic, understanding the factors contributing to these changes, including their underlying causes, is of paramount importance.
Peigen Lin, the lead author of the paper, emphasizes that people should be cognizant of the fact that alterations in the circulation patterns of the Arctic Ocean could pose a threat to the climate. It is crucial to recognize that the concerns extend beyond just melting ice and the loss of animal habitats. Lin, an associate professor at the School of Oceanography in Shanghai Jiao Tong University, conducted this research during his tenure as a postdoctoral investigator at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.