Not quite the result that was expected as global climate warming was to open the Arctic Ocean to shipping.
Sea ice choke points reduce the length of the shipping season in the Northwest Passage
Abstract
Arctic sea ice has shifted from a perennial (older, thicker ice) to a seasonal (younger, thinner) ice regime, leading to the increasingly common belief that shipping through Canada’s Northwest Passage is becoming more viable. Here, we use the Risk Index Outcome values derived from the Polar Operational Limit Assessment Risk Indexing System and analyze recent changes to shipping season lengths along individual sections of the Northwest Passage routes from 2007 to 2021. Results show that multi-year ice flushed southward from high-latitude regions maintains the so-called choke points along certain route sections, reducing overall shipping season length. There is considerable spatiotemporal variability in shipping season lengths along the southern and northern routes. Specifically, parts of the northern route exhibit a decrease of up to 14 weeks over the 15 years. The variability of shipping season and, in particular, the shortening of the season will impact not only international shipping but also resupply and the cost of food in many Arctic communities, which require a prompt policy response.
From the paper:
Long-term observational studies conclude that sea ice has declined across the Canadian Arctic and this may increase ship navigability in many regions of the Northwest Passage31,32. Indeed, the northern route of the NWP became almost completely ice-free for the first time in human memory during the summer of 200733 and since then experienced exceptionally light conditions in 2011 and 201234.
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Of the four regions, the full shipping season length of the Eastern Beaufort Sea (Section 1) has decreased the most overall, by 14 weeks, from 27 weeks in 2007 to 13 weeks in 2021 (Fig. 4.1). There was a statistically significant decrease in all three of the intra-annual seasons, with a comparable reduction in the number of weeks in each, of up to 6 weeks. Interannual variation shows that the year with the shortest shipping season was 2018, when the Eastern Beaufort Sea was only accessible to PC7 vessels for 3 weeks.
The M’Clure Strait (Section 2) full shipping season has also significantly shortened, although to a lesser degree, by 5 weeks (Fig. 4.2). Here, the reduction occurred primarily in the mid season, on a statistically significant trend from 6.5 weeks to 2 weeks.
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The processes of MYI southward transport through the CAA is not well captured in climate models and presents a false sense of optimism regarding the practical usage of the Northwest Passage from purely climate model based studies. Indeed, as ice in the LIA continues to decline towards mid-century and beyond, the process of southward MYI transport will also decline but it will not stop and will continue to be problematic to navigation until the supply of MYI is exhausted in the LIA.
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Overall, we conclude that consistent lengthening of the shipping season along the entirety of all the routes of NWP will be highly variable, and assumptions of less sea ice enabling safe passage along the northern route should be avoided.
The issues are there is a lot of variability, and models do not, at this point, accurately represent the real world.
