A commercial ship makes its way through Tasiujaq, formerly Eclipse Sound, in a section of the Northwest Passage located between Baffin Island and Bylot Island, in August, 2017.Supplied
A long-anticipated effect of climate change is that the loss of summer sea ice in the Arctic will make it easier for vessels to use the Northwest Passage as a shortcut between the Pacific and Atlantic oceans.
Now, a new study has demonstrated the reverse. The annual window for safe shipping across the top of North America appears to be shrinking, with ramifications for safety and the Arctic marine environment as more commercial and cruise ships seek to make their way through the region each year.
“We were surprised,” said Alison Cook, a postdoctoral researcher with the Scottish Association for Marine Science in Oban and the lead author on the study. “We expected the data to clearly show that there’s less ice, therefore that’s why there’s more ships going through. But it wasn’t that simple.”
Dr. Cook, who conducted the work in collaboration with researchers at the University of Ottawa and Environment and Climate Change Canada, said the likely explanation is that a more rapid melting of the thin sea ice that forms atop the ocean every winter is allowing thicker, multiyear ice to move around with greater ease, clogging up the channels that ships use to traverse Canada’s Arctic archipelago.
The study was published Thursday in the journal Nature Communications Earth & Environment.
Its authors drew on 15 years of data gathered by Canada’s Radarsat series of remote sensing satellites, starting in 2007. The satellites use radar signals that can penetrate cloud cover and distinguish between open and ice-covered water in the Arctic. The data were then used to show an average length of season when the Northwest Passage would be open to ships each year.
Road blocks
Based on satellite data collected between 2007 and 2021, the Northwest Passage is only safe for about 10 weeks per year for vessels that are not equipped to break through thick, multiyear sea ice. As the Arctic has warmed, an overall reduction of thin ice has allowed thicker ice to move into places such as Peel Sound and Larsen Sound, where it forms chokepoints along the more favourable but longer southern route. Other routes fare even worse.
Mean season length
In weeks
Southern Route
Northern Route 1
Northern Route 2
Prince Regent Inlet
0
10
20
30
39
400 km
Beaufort Sea
Peel
Sound
ALASKA
Baffin
Island
YUKON
Larsen
Sound
NWT
NUNAVUT
THE GLOBE AND MAIL, SOURCE: SCOTTISH
ASSOCIATION FOR MARINE SCIENCE; UNIVERSITY
OF OTTAWA; ECCC
Road blocks
Based on satellite data collected between 2007 and 2021, the Northwest Passage is only safe for about 10 weeks per year for vessels that are not equipped to break through thick, multiyear sea ice. As the Arctic has warmed, an overall reduction of thin ice has allowed thicker ice to move into places such as Peel Sound and Larsen Sound, where it forms chokepoints along the more favourable but longer southern route. Other routes fare even worse.
Mean season length
In weeks
Southern Route
Northern Route 1
Northern Route 2
Prince Regent Inlet
0
10
20
30
39
400 km
Beaufort Sea
Peel
Sound
ALASKA
Baffin
Island
YUKON
Larsen
Sound
NWT
NUNAVUT
THE GLOBE AND MAIL, SOURCE: SCOTTISH ASSOCIATION FOR
MARINE SCIENCE; UNIVERSITY OF OTTAWA; ECCC
Road blocks
Based on satellite data collected between 2007 and 2021, the Northwest Passage is only safe for about 10 weeks per year for vessels that are not equipped to break through thick, multiyear sea ice. As the Arctic has warmed, an overall reduction of thin ice has allowed thicker ice to move into places such as Peel Sound and Larsen Sound, where it forms chokepoints along the more favourable but longer southern route. Other routes fare even worse.
Mean season length
In weeks
Southern Route
Northern Route 1
Beaufort Sea
Northern Route 2
Prince Regent Inlet
0
10
20
30
39
ALASKA
Peel
Sound
Baffin
Island
YUKON
Larsen
Sound
NWT
NUNAVUT
.
200 km
THE GLOBE AND MAIL, SOURCE: SCOTTISH ASSOCIATION FOR MARINE SCIENCE; UNIVERSITY OF OTTAWA; ECCC
Of particular interest to the team are ships classified as Polar Class 7. This category includes all vessels that can only manage ice less than 70 centimetres thick, with some inclusions of thicker ice. Such ships would only be able to navigate the Arctic during those weeks in the late summer and autumn when the Northwest Passage is at its most ice-free. The class also represents the largest number of ships now travelling through the Arctic each year.
Using the ice data, the team was able to determine an average length of shipping season for the class. They found that even for the most favourable, southern route through the passage, a typical season may last less than 10 weeks before ice makes the way impassable. Two sections of the southern route, Larsen Sound and Peel Sound, appear to be among the most reduced in access over the time period considered in the study. Along the eastern Beaufort Sea, the shipping season has declined from more than 20 weeks to about 17.
The situation is no better for more northern routes using the M’Clure Strait, which are shorter and therefore more attractive to shipping companies. There the data show that the average shipping season for Polar Class 7 vessels has been less than five weeks since 2017.
The implication is that ships expecting to move through the region with increased ease may, in fact, be more likely to find themselves in dangerous circumstances. In addition to threats to crew and passenger safety, shipping accidents in the Arctic are a concern because of the consequences of fuel leaks and other effects on Arctic ecosystems.
Jackie Dawson is a co-author of the study and a professor at the University of Ottawa who specializes in the human dimensions of climate change in the Arctic. She said that the research can offer some guidance to government officials looking to allocate limited resources toward safer navigation across a vast area. The knowledge can also help communities and others who are most likely to be on the front lines in a rescue situation.
“Knowing how and where we may see ship-ice incidents could be useful for community training and resourcing,” Dr. Dawson said.
Dustin Isleifson, director of the University of Manitoba’s Centre for Earth Observation Science, who was not involved in the study, said the authors make a plausible case that multiyear sea ice poses an increasing risk to Arctic shipping. He called on the Canadian government to enhance its remote sensing capabilities and bolsters its cleanup response plans in case of future accidents.
“Research and development into oil spill response in Arctic waters is crucial to develop at this point in time,” he said. “We simply aren’t ready for such a disaster.”
The study’s authors said that while the warming of the Arctic is accelerating, the effect they discovered is not going to change any time soon because of the abundance of multiyear ice that can now move southward into the Northwest Passage.
“There is a presumption that the Northwest Passage will soon be a viable new shipping route. But it’s not the case,” Dr. Cook said.
The study is just the latest to show the complexities of climate change and its impact on shipping. Last March, research by a French team published in Geophysical Research Letters showed there has been a greater than 22-per-cent increase in wave height in the Arctic Ocean owing to the depletion of sea ice.