The retreat of sea ice in the Arctic is providing welcome time savings — and thus potentially lower costs — for international trade, as ships can increasingly use the shorter Northern Sea Route, north of Russia, and the Northern Passages, in North America. However, these savings could be much smaller in the future as rising temperatures and sea-ice loss lead to more fog along the ice edge, requiring ships to sail slower, according to recent research.
For decades, Arctic sea ice has been in retreat, and today northern sea lanes are ice-free enough that they are now navigable by ships other than icebreakers. Being able to sail northwards means being able to bypass longer, southerly routes that pass through either the Panama or Suez canal.
Although ice may no longer pose as much danger on northern routes as it once did, other hazards have emerged. This is because the cold Arctic air increasingly encounters comparatively warm water as sea ice recedes, and the warm vapor condenses into fog that can require ships to sail at slower speeds. Isolated chunks of ice pose an even greater risk to vessels in foggy conditions.
For the study, published in Geophysical Research Letters, the Chinese research team used data on fog in the Arctic collected between 1979 and 2018, as well as climate projections from the Coupled Model Intercomparison Project. They examined how climate change has affected how often fog occurs along Arctic shipping routes, and how conditions will change this century. In addition, the researchers also modeled alternative routes that could minimise the number of foggy days during the Arctic crossing.
“The future of shipping in the Arctic is unclear, but fog could pose a significant challenge,” said Xianyao Chen, a physical oceanographer at the Ocean University of China and author of the study. “When designing shipping routes across the Arctic, we need to consider the impact of fog.”
According to the results, ships are more likely to encounter fog in the Northwest Passages, which is much narrower and where there are more islands, than they are in the open Northern Sea Route. In the Northwest Passages, the fog is also more persistent, which could add up to three days to sailing times. In the less foggy Northern Sea Route, the effect of fog would be to add no more than a day to travel times.
The study also found that sailing further from the ice edge would decrease the effect of fog.
Fog is already cutting into time gained by taking the much shorter Arctic routes. On foggy days, vessel speeds are slower than on clear days, according to Mr Chen. As fog is expected to become more common in the Arctic, shipping could also slow down if routes are not adjusted. Given the high cost of sailing in the Arctic — daily operating costs for large container ships typically reach $50,000 to $150,000 — a multi-day delay would make sailing northern routes much more expensive.
“Avoiding ice is critical,” said Scott Stephenson, a physical scientist at the RAND Corporation who was not affiliated with this study. “This study did a good job at identifying the risks of fog — an important environmental constraint in the Arctic, and one that has largely been ignored.”
Julia Hager, PolarJournal
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