Record fresh water from the Arctic will flow into the Labrador Sea, affecting local and global oceans

Fresh water is accumulating in the Arctic Ocean. The Beaufort Sea, which is the largest freshwater reservoir in the Arctic Ocean, has increased its freshwater content by 40% in the past two decades. How and where that water will flow into the Atlantic Ocean is important for local and global ocean conditions.

A study by the University of Washington, the 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 the wider marine passages that connect to the northern seas. from Europe. The open access study was published on February 23 in Nature Communications.

“The Canadian archipelago is an important channel between the Arctic and the North Atlantic,” said lead author Jiaxu Zhang, UW postdoctoral researcher at the Cooperative Institute for Climate, Ocean and Ecosystem Studies. “In the future, if the winds get weaker and fresh water is released, there is a potential for this large amount of water to have a major influence on the Labrador Sea region.”

The discovery has implications for the marine environment of the Labrador Sea, as Arctic water tends to be cooler, but also rich in nutrients. This route also affects the major ocean currents, namely a conveyor belt circulation in the Atlantic Ocean where the coldest and heaviest water sinks in the North Atlantic and returns along the surface like the Gulf Stream. Cooler, lighter water entering the Labrador Sea can slow reverse circulation.

“We know that the Arctic Ocean has one of the biggest signs of climate change,” said co-author Wei Cheng, from the UW Cooperative Institute for Climate, Ocean and Atmospheric Studies. “At the moment, this fresh water is still trapped in the Arctic. But when it comes out, it can have a very big impact.”

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

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

“People have spent a lot of time studying why fresh water in the Beaufort Sea has become so high in recent decades,” said Zhang, who started work at the Los Alamos National Laboratory. “But they rarely care where fresh water goes, and we think this is a much more important problem.”

Using a technique developed by Zhang to track the salinity of the ocean, the researchers simulated the circulation of the ocean and followed the spread of fresh water from the Beaufort Sea in a past event that took place from 1983 to 1995.

The experiment showed that most freshwater reached the Labrador Sea through the Canadian archipelago, a complex set of narrow passages between Canada and Greenland. This region is poorly studied and considered less important for freshwater flow than the Fram Strait, which connects to the northern European seas.

In the model, the 1983-1995 freshwater release traveled mainly along the North American route and significantly reduced salinity in the Labrador Sea – a renewal of 0.2 parts per thousand at its shallower west edge, off the coast of Newfoundland and Labrador, and 0.4 parts per thousand within the Labrador Current.

The volume of fresh water now in the Beaufort Sea is about twice the size of the case studied, at more than 23,300 cubic kilometers, or more than 5,500 cubic miles. This volume of fresh water released in the North Atlantic can have significant effects. The exact impact is unknown. The study focused on past events, and current research is looking at where the current accumulation of fresh water can end and what changes it can trigger.

“A release of freshwater of this size in the subpolar North Atlantic could impact a critical circulation pattern, called Atlantic Meridional Overturning Circulation, which has a significant influence on the climate in the Northern Hemisphere,” said co-author Wilbert Weijer of the Los Angeles National Laboratory. We do.