A Review of Arctic–Subarctic Ocean Linkages: Past Changes, Mechanisms, and Future Projections

Abstract

Arctic Ocean gateway fluxes play a crucial role in linking the Arctic with the global ocean and affecting climate and marine ecosystems. We reviewed past studies on Arctic–Subarctic ocean linkages and examined their changes and driving mechanisms. Our review highlights that radical changes occurred in the inflows and outflows of the Arctic Ocean during the 2010s. Specifically, the Pacific inflow temperature in the Bering Strait and Atlantic inflow temperature in the Fram Strait hit record highs, while the Pacific inflow salinity in the Bering Strait and Arctic outflow salinity in the Davis and Fram straits hit record lows. Both the ocean heat convergence from lower latitudes to the Arctic and the hydrological cycle connecting the Arctic with Subarctic seas were stronger in 2000–2020 than in 1980–2000. CMIP6 models project a continuing increase in poleward ocean heat convergence in the 21st century, mainly due to warming of inflow waters. They also predict an increase in freshwater input to the Arctic Ocean, with the largest increase in freshwater export expected to occur in the Fram Strait due to both increased ocean volume export and decreased salinity. Fram Strait sea ice volume export hit a record low in the 2010s and is projected to continue to decrease along with Arctic sea ice decline. We quantitatively attribute the variability of the volume, heat, and freshwater transports in the Arctic gateways to forcing within and outside the Arctic based on dedicated numerical simulations and emphasize the importance of both origins in driving the variability.

Fluctuating Atlantic inflows modulate Arctic atlantification

“…( E and F ) September sea-ice extent trends (E) and the TI-NDVI (F) for 1992 to 2006 (blue) and 2007 to 2021 (red) as a function of longitude. ( G ) Diagram of sea ice drift and upper ocean circulation (blue arrows), as well as Atlantic water circulation (red arrows) ( 53 ). FJL-NZ, TPD, and BG indicate Franz Joseph Land–Novaya Zemlya pass, TransPolar Drift, and Beaufort Gyre, respectively.…”

Recent and projected shifts from surface density compensation to warming, freshening and stronger stratification in the subpolar North Atlantic

“…Following evaluation of the ECCOv4 reanalysis, Tesdal and Haine (2020) proposed that Arctic Ocean freshwater will become 'an increasingly important source of future freshwater increases in the subpolar North Atlantic'. In summary, a recent review of past and future Arctic-Subarctic ocean linkages highlights that Arctic outflow salinity fell to record lows in the Fram and Davis straits during the 2010s, while CMIP6 models project further increases in freshwater export through Fram Strait associated with both increasing volume transport and decreasing salinity (Wang et al 2023).…”

Arctic freshwater impact on the Atlantic Meridional Overturning Circulation: status and prospects

“…The projected increase in atmospheric moisture flux convergence is moderately well established [20][21][22][23], but the anticipated changes to the marine outflows are poorly known. Moreover, well-known, stubborn biases exist in the Arctic Oceans of CMIP6 models [11,[24][25][26][27].…”

“…Proshutinsky et al [ 8 ] estimate an extra of liquid freshwater between 2003 and 2018 in the Beaufort Gyre, which is the largest Arctic freshwater reservoir. This build-up of liquid freshwater is shown in figure 1 (Liquid Storage panel), which shows observations of liquid freshwater volume increasing (red line; see [ 7 , 10 ] for full discussion and details on the data sources; and see [ 11 ] for a recent update). Figure 1 reveals the sources of the extra liquid freshwater too: they are reduced sea ice (Solid Storage panel), increased runoff and increased inflow through Bering Strait (left hand panels).…”

“…It focuses on the putative impacts of anthropogenic Arctic freshening on the SPNA and AMOC weakening, but other interesting questions abound 4. For the gateway flux observations, see Wang et al[11], and the references therein. For hydrographic observations, icetethered profilers[87] and the Argo program are particularly valuable.…”