The Northwest Passage connects ship traffic through the Arctic Ocean to connect the Atlantic Ocean with the Pacific Ocean. The passage winds through a cluster of islands north of mainland Canada, offering a potentially shorter route between oceans but posing significant challenges due to the unpredictable Arctic waters and shifting ice.
The search for a passage to shorten ship travel between Europe and Asia was the subject of many explorers for centuries. It wasn’t until 1906 when Norwegian explorer Roald Amundsen completed the first successful transit through the Northwest Passage.
Arctic sea ice is limiting passage through the Arctic
Since then, the number of ships traveling around the Arctic ice cap has been limited. In August of 2007, the Northwest Passage was ice free and navigable without an icebreaker since satellite monitoring of the region began in 1978.
With climate change accelerating sea ice melt in the polar regions, some researchers had predicted that there would be an increase in the number of days when the Northwest Passage would be ice free and therefore navigable by ship. Declining sea ice thickness and extent, driven by rising global temperatures, led to the hypothesis that the passage might be navigable for longer periods each summer. Over the past forty years, satellite data has shown a consistent reduction in sea ice cover in the Arctic region, with the melting season growing longer and the ice losing its longevity.
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A shorter shipping season for the Northwest Passage
However, recent research highlights a paradox: while the overall ice cover in the Arctic is shrinking, the passage has become more clogged with ice in recent years, shortening the shipping season.
According to a 2024 study published in the journal Communications Earth & Environment, the southward drift of Arctic ice has been obstructing the Northwest Passage more frequently. This drift has led to an accumulation of thick, multiyear ice in the channels of the passage, creating significant challenges for vessels attempting the journey.
In this study, researchers used data from a risk assessment system to analyze the length of the shipping season along different parts of the Northwest Passage from 2007 to 2021. The findings show that older, thick ice moving south from higher latitudes continues to block key sections of the passage, shortening the overall shipping season.
Researchers also found that there is significant variation in the length of the shipping season between the northern and southern routes, with some areas of the northern route seeing a reduction of up to 14 weeks over the past 15 years.
The future of the Northwest Passage
The future of the Northwest Passage as a reliable shipping route remains uncertain. While climate change is reducing overall ice cover, the increased movement of multiyear ice into the passage could continue to limit its use. The presence of this thick, resilient ice in the Canadian Arctic Archipelago and around Greenland places it in a position to infiltrate the channels of the passage, maintaining choke points that are hazardous to ships.
References
Cook, A. J., Dawson, J., Howell, S. E., Holloway, J. E., & Brady, M. (2024). Sea ice choke points reduce the length of the shipping season in the Northwest Passage. Communications Earth & Environment, 5(1), 362.
Doermann, L. (2024, August 8). Sea ice chokes the Northwest Passage. NASA Earth Observatory.
Fonte : National Geographic
