Record high Arctic freshwater will flow into the Labrador Sea and erode local and global oceans

Fresh water accumulates in the Arctic Ocean. The Beaufort Sea, the Arctic Ocean’s largest freshwater reservoir, has increased freshwater levels by 40% over the past two decades. How and where this water flows into the Atlantic Ocean is important to local and global ocean conditions.

A study by the University of Washington, Los Alamos National Laboratory and the National Oceanic and Atmospheric Administration shows that this freshwater travels through the Canadian archipelago to reach the Labrador Sea, rather than through the wider seaways that connect to the seas in North -Europe. The open access study was published in February 23 Nature Communications

“The Canadian archipelago is an important channel between the Arctic and the North Atlantic,” said lead author Jiaxu Zhang, a UW postdoctoral fellow at the Cooperative Institute for Climate, Ocean and Ecosystem Studies. “In the future, as the wind weakens and the fresh water is released, there is a possibility that this large amount of water will have a major impact in the Labrador Sea area.”

The finding has implications for the Labrador Sea’s marine environment, as Arctic water tends to be fresher, but also rich in nutrients. This path also affects larger ocean currents, namely a conveyor belt circulation in the Atlantic Ocean in which colder, heavier water sinks into the North Atlantic Ocean and returns along the surface as the Gulf Stream. Fresher, lighter water entering the Labrador Sea can slow that overturning circulation.

“We know that the Arctic Ocean has one of the biggest signals of climate change,” said study co-author Wei Cheng of the UW-based Cooperative Institute for Climate, Ocean and Atmosphere Studies. “Right now, this fresh water is still trapped in the Arctic. But once it comes out, it can have a very big impact.”

Fresh water is reaching the Arctic Ocean through rain, snow, rivers, inflows from the relatively cooler Pacific, as well as the recent melting of the sea ice in the Arctic Ocean. Fresher, lighter water floats at the top, and clockwise in the Beaufort Sea push that lighter water together to create a dome.

When those winds relax, the dome will flatten and the fresh water will be released into the North Atlantic Ocean.

“People have spent a lot of time studying why freshwater levels in the Beaufort Sea have risen so high in recent decades,” said Zhang, who began work at Los Alamos National Laboratory. “But they rarely care where the fresh water goes, and we think that’s a much more important problem.”

Using a technique that Zhang developed to track ocean salinity, the researchers simulated ocean circulation and tracked the distribution of freshwater in the Beaufort Sea during a past event that occurred from 1983 to 1995.

Their experiment showed that most of the fresh water reached the Labrador Sea through the Canadian Archipelago, a complex series of narrow passages between Canada and Greenland. This area has been poorly studied and was thought to be less important to the freshwater flow than the much wider Fram Strait, which communicates with the Northern European seas.

In the model, the freshwater release from 1983-1995 traveled largely along the North American route and significantly reduced salinity in the Labrador Sea – a 0.2 parts per thousand change on the shallower western edge, off the coast of Newfoundland and Labrador. and of 0.4 parts per thousand within the Labrador stream.

The volume of fresh water now in the Beaufort Sea is about twice that of the case study studied, namely more than 23,300 cubic kilometers or more than 5,500 cubic miles. This volume of fresh water discharged into the North Atlantic Ocean can have significant consequences. The exact impact is unknown. The study focused on past events, and current research looks at where today’s freshwater accumulation could end and what changes it could cause.

“A release of fresh water of this magnitude into the subpolar North Atlantic Ocean could affect a critical circulation pattern called Atlantic Meridional Overturning Circulation, which has a significant impact on the Northern Hemisphere’s climate,” said study co-author Wilbert Weijer. from Los Alamos National Lab.