Ocean temperatures in the Atlantic set new records in 2022

Ocean temperatures in Atlantic Canada will hit record highs again in 2022, according to the latest assessment from the Federal Department of Fisheries and Oceans.

Results from the annual monitoring program for the Atlantic zone show that surface, center and bottom temperatures were well above normal last year.

“It was widespread. It was everywhere,” said Peter Galbraith, a DFO researcher in Mont-Joli, Que. “It was really hot all over the zone.”

Fisheries and Oceans uses 45 indices – a combination of multiple indicators – to measure ocean conditions associated with temperatures in the Gulf of Maine south of Nova Scotia, the Scotian Shelf, the Gulf of St. Lawrence and off the coast of Newfoundland and Labrador.

“Those are alarm bells”

The data is collected using onboard measurements, gliders, fixed and floating buoys and satellites.

In 2022, 43 indices were above normal and 16 were the highest ever recorded, DFO said in its report on oceanographic conditions released this month.

“Those are alarm bells. It means paying attention and being careful,” said Pierre Pepin, a biologist at DFO in St. John’s.

“That’s essentially what those things mean. And the extent to which that’s integrated into the decision-making process is still evolving.”

Multiple records were set in the Gulf of St. Lawrence in 2022.

The average sea surface temperature in the gulf from May to November was the highest since records began in 1981: 1.6 C above normal.

In August, surface temperatures set another 41-year record, averaging 18.2C – which is 2.2C higher than normal. In September, temperatures averaged 15.5 C, or 2.5 C above normal.

Galbraith called these variations “really huge”.

September was also notable for Hurricane Fiona tossing up the seas and dropping surface temperatures by 6C in a two-week period – but those temperatures were still hitting new highs.

Age-old heat record from 2015 surpassed

The gulf’s cold interlayer in summer — subsurface water left over from the previous winter — was the second warmest since records began in 1985.

Meanwhile, deeper water set high temperature records at 150, 200, 250 and 300 metres, surpassing the 7 C threshold for the first time.

That’s a full degree higher than in 2015, when a 100-year-old record was broken.

“Since 2015, it’s been going up in small increments every year,” Galbraith said.

Warmer water coming from the Gulf Stream is now dominant in deeper strata and the deepest channels have seen a big drop in oxygen levels.

DFO says the St. Lawrence Estuary, from Quebec City to Pointe-des-Monts, Que., and the Gulf of St. Lawrence are both currently undergoing “significant changes” in chemical and biological conditions.

Climate change trends

The DFO report states that during ice-free months, surface waters in the Atlantic have “mainly followed climate change-induced warming trends in the atmosphere” and set records in the summer of 2022.

Soil temperatures were significantly above normal throughout the zone, including record highs in the northern Gulf of St. Lawrence, off southern Newfoundland and on the Scotian Shelf.

“What we’re starting to see, or at least I’m starting to see in this data, is that the one-off incidents are much more common and if you have one-off incidents that are more common, that’s an indicator of change,” Pepijn said.

“I think it’s fair to say there’s a strong climate change component to it.”

Why warming is expected to continue

Warm water is expected to persist for years in the Gulf of St. Lawrence and Scotian Shelf, according to DFO.

The deep water sucked into the gulf from the Atlantic Ocean mixes well offshore.

It takes two years to get from the continental margin slope to the Laurentian Channel, another two years to reach the Cabot Strait between Newfoundland and Cape Breton, and another three years to reach the inner mouth.

Galbraith said there’s no sign yet of a dominant “blob” of colder water from the Labrador Current entering the mix.

Winners, losers and mackerel

“All we see is still warm water there,” he said. “So there is no respite for the Gulf of St. Lawrence and Scotian Shelf. They will continue to experience warm conditions for at least several more years.”

This may be detrimental to some cold-water species, such as snow crab, which can tolerate a narrow thermal band, or northern shrimp, especially in parts of the gulf where oxygen levels have fallen with the arrival of warmer water.

“Warm water is not the preferred environment for most of these species,” Pepijn said. “They tend to have lower productivity. They tend to have lower survival rates. They’re trying to get out of very warm waters.”

In the Gulf of St. Lawrence, DFO reports healthy halibut stocks and thriving lobster populations.

Responses to warming water can be misleading, Pepijn said, pointing to mackerel’s behavior “which basically follows warm water everywhere.”

“You’re going to see them more often. It doesn’t necessarily mean they’re abundant in those areas. It means you’re seeing them more often,” he said.

“And so it gives the impression that something has changed. But you have to be careful how you interpret those kinds of observations.”