Situated at the very cap of our planet, the Arctic Ocean is a massive body of water, extending over an area of 5,440,000 square miles. However, while remote, the ocean is still connected to the global ocean–and by extension, its influence–by several oceanic straights. These connections include the Bering Strait to the Pacific, the Nares Strait to the Baffin Sea, and, most important to the global circulation, the Fram Strait to the Atlantic (polartrec.com).
Arctic Ocean circulations (divediscover.whoi.edu)
The importance of this strait should not be understated. For instance, it is often ice-free for most of the year, which is very unusual for its location at such a northern latitude. This is mainly due to the fact that it is the entrance to the Arctic Ocean taken by the warm North Atlantic Current, which brings its influence of warmer, saltier water deeper into the Arctic. However, it should be understood how its influence has been changing in recent years (Polyakov et al, 2020).
As mentioned previously, the Atlantic waters enter into the Arctic Ocean as the North Atlantic Current moves northward through the Fram Strait. Typically, the warmer, saltier Atlantic waters only move into the Arctic Ocean to a certain point. Where this happens, the Atlantic waters sink below the layer of the colder, fresher Arctic waters due to its increased density. However, the two layers do not immediately contact each other. Between them, there forms the Cold Halocline Layer (Greek, salt-slope). This layer acts as a boundary, limiting the effects of the Atlantic waters on the Arctic waters above. Yet, in recent years the Atlantic waters have been moving much further into the Arctic Ocean. This has had the effect of a decrease in the thickness of the Cold Halocline Layer, and allowing a greater influence of the warmer, saltier Atlantic waters on the Arctic waters. The main consequence of this has been the net decrease in the amount of sea ice observed in the Arctic Ocean (Polyakov et al, 2020).
Needless to say, this is a worrying prospect, as the general decrease in Arctic sea ice has many ecological and environmental consequences. It is imperative to further our understanding of these effects, and due to this, the topic has been at the forefront of recent research.