The Arctic, as one of the fastest changing oceans and regions on Earth, “lends an urgency to understanding it better,” including understanding the Beaufort Gyre, says WHOI physical oceanographer Isabela Le Bras, a principal investigator on the Beaufort Gyre Observing System (BGOS). The gyre is a massive clockwise ocean circulation pattern in the Arctic Ocean north of Alaska. The currents swirl around as if contained in a bowl about 1000 kilometers across, she says.
However, something is amiss with the Beaufort Gyre. It has been accumulating freshwater but it hasn’t released a significant freshwater pulse to the North Atlantic Ocean in about 20 years, far beyond its expected cycle.
Oceanus sat down with Le Bras to learn more about this unprecedented situation and learn about the possible ramifications locally and globally.
Oceanus: Why is the Beaufort Gyre important?
Le Bras: The gyre sets the ocean temperature and salinity over a large portion of the Arctic, which impacts how the ocean and atmosphere interact with each other. In turn, that influences the overall climate. The Beaufort Gyre also impacts how freshwater moves from place to place within the ocean, which can affect ocean currents across the globe.
Oceanus: How has the gyre operated in the past?
Le Bras: The gyre’s large swirling circulation has accumulated and then released freshwater to other parts of the ocean, with an approximately 5-10-year pattern going on, we think, at least since the 1930s. Previous freshwater releases in the 1970s and 1980s have been associated with short-lived freshening events in the North Atlantic.
Oceanus: What is so concerning now?
Le Bras: Since the late 1990s, the gyre has been stuck in this phase of collecting freshwater and not releasing it. It has been about 20 years now since we’ve seen a flip in the cycle that used to happen every 5-10 years. From 2003 to 2018, we have seen a 40% growth in freshwater in the gyre relative to the climatology in the 1970s.
We don’t think this has ever happened before. We have an unprecedented amount of freshwater up there. We are not sure what is going to happen if and when this freshwater is released to the rest of the ocean. A sudden release of freshwater could shut down the Atlantic’s large-scale circulation that stabilizes our climate. This is because the Arctic freshwater would be lighter than most of the water in the subpolar North Atlantic and float atop it like oil over water. This in turn would stop or at least slow down deep-water formation which is necessary for this circulation system to overturn.