North Atlantic Current could temporarily stop — or even reverse — over next century

Aaron Beswick (abeswick@herald.ca)

Published: Dec 31, 2019 at 7:18 a.m.

Updated: Dec 31, 2019 at 1:08 p.m.

The Atlantic Ocean Circulation transports relatively warm water from the Gulf of Mexico to northwestern Europe. - Sven Baars / University of Groningen - Contributed

With good news seeming such a rare commodity these days, we’ll start with that: Don’t let fear of a total collapse of the North Atlantic Current keep you awake tonight.

Because, according to a group of Dutch scientists, that’s unlikely to happen over the next thousand years.

Phew.

The study published last week by researchers at the universities of Utrecht and Groningen does raise concerns about how climate change will affect the currents of water that move off Nova Scotia.

And the slowing of the North Atlantic Current due to more rain on the ocean and melting Greenland glaciers will matter for our fishing industry — worth more than $2 billion last year — and agriculture and weather.

But how it will affect Atlantic Canada isn’t something their computer modelling sought to answer. They warn that there’s a 15 per cent chance that the current could stop temporarily or even reverse over the next century, leading to colder weather in Europe.

For us, it’s actually more complicated than for Europe.

Because our lives are governed by the eternal shoving match of two currents — the Labrador Current bringing cold water down from the north and the Gulf Stream, which brings warm water from the south.

It’s the latter that ultimately branches off to become the North Atlantic Current and results in the ability of palm trees to be viable in Ireland when they don’t have a hope here.

The Labrador Current carries cold, dense saltwater that sinks to the bottom of the ocean and wells up along the edge of the Scotian Shelf carrying nutrients from the deep into the light where they result in a bloom of biological productivity that matters to our fisheries.

However, as is addressed by the Dutch study, the increased rainfall caused by climate change along with melting ice sheets is adding lighter freshwater to the mix. That keeps it near the surface and affects its struggle with the Gulf Stream.

“This study looks at what could happen in Europe but already we’re seeing things happen in Atlantic Canada,” said Susanna Fuller, vice-president of projects and operations at Oceans North.

“The movement of right whales to Gulf of St. Lawrence is a prime example of something that wasn’t expected. There are far fewer mackerel and herring off coast — how much over fish vs climate change I don’t think we know yet.”

Two studies published in the journal Nature recently showed that the Gulf Stream is also slowing. As it slows it wraps closer to the coast — that has resulted in warmer waters off Nova Scotia.

Lobster landings have done very well. Groundfish like cod have failed to recover on the Scotian Shelf from historical overfishing despite the removal of this pressure.

“What it all means — changes in the Gulf Stream versus where the Labrador Current goes — I don’t think we know,” said Fuller.

“But it points to a need for more study and for us to be prepared for more unexpected changes.”