As Nova Scotians dug out from a spring snowstorm this week, scientists 200 kilometres off the coast were measuring record-high ocean temperatures in deep water that reached 14 C.
That’s 14 C. In April.
“It’s sort of a shock,” said Dave Hebert, a veteran ocean climate scientist with the Department of Fisheries and Oceans in Halifax. “I was really surprised it was that high.”
The 14 C reading was taken by scientists on board the Canadian Coast Guard ship Hudson on April 8 and 9 in the Northeast Channel, a channel between Georges Bank and the Scotian Shelf that is 60 kilometres wide and 250 metres deep.
Entire column unusually warm
The channel is a pathway for offshore water flowing into the Gulf of Maine and Bay of Fundy.
Hebert said the entire water column was abnormally warm, a record high and well above the normal variability of one degree.
Dave Hebert said the high temperatures surprised him.
“This is six degrees above normal going into the Gulf of Maine. I expect the Gulf of Maine will be really warm this summer,” he said.
Last December Georges Basin — a deep water hole in the Gulf of Maine — also registered the warmest temperature in 40 years of data collection.
These may be eddies of warmer water from the Gulf Stream making their way into the coast, but warmer water is being seen throughout the region.
For most of the past decade, ocean temperatures in the Maritimes have been consistently above normal. The record high was 2012, which on climate temperature maps shows as a red blob around Nova Scotia.
“It’s not as warm as 2012, but it’s getting close,” said Hebert.
Gulf of St. Lawrence warming
With the exception of northern Newfoundland and Labrador, in 2016 sea ice arrived later, left earlier, or did not appear at all at any significant level.
That was the case off northern Cape Breton and the Scotian Shelf. “The water going into the Gulf of St. Lawrence in 2016 was the warmest-ever and 2017 was second-warmest,” said Hebert.
In 2017, warming water in the gulf coincided with two unusual events. There was the unexpected appearance of large numbers of endangered North Atlantic right whales, with tragic consequences. They may have been feeding zooplankton that had moved into the area.
There was also an unprecedented northward migration of striped bass out of their traditional range in the southern gulf.
Federal fisheries biologist Paul Chamberland said it was not a few individuals exploring new territory, but tens of thousand moving to areas where they have never been seen before: the north shore of Quebec and the coast of Labrador.
“The warmer waters would probably make it possible for these fish to expand their range,” he said.
So, is it climate change?
Hebert is reluctant to draw a link with climate change. He points out that ocean temperatures vary over decades. They were below normal on the Scotian Shelf in the 1960s and 1970s.
“That’s why you have to be very careful when you do trends, like when you pick your start and and stop times,” he said. “If you started at the very coldest time and went to now, you would have a very big trend, whereas if you took a longer time series, it might not be as big.”