Ships are projected to navigate whole year-round along the North Sea route by 2100

The Arctic is experiencing rapid sea ice retreat due to global warming, opening up the possibility of year-round navigation along Arctic shipping routes. These routes, such as the Northern Sea Route (NSR), Northwest Passage (NWP), and Transpolar Sea Route (TSR), offer the potential to significantly reduce transport distances and times between Europe and Asia, leading to decreased fuel consumption and carbon emissions. The potential economic benefits are substantial, as trade between Europe and Northwest Asia constitutes a considerable portion of global trade. However, the feasibility of Arctic maritime transport is influenced by various factors, including sea ice concentration (SIC), sea ice thickness (SIT), sea ice motion (SIM), weather conditions (strong winds, low visibility, low temperatures), and water depth. Existing research often focuses on the effects of individual environmental factors on navigability and predominantly uses non-strengthened open water (OW) ships or medium-strengthened Polar Class 6 ships, neglecting the widely used thin-strengthened Polar Class 7 (PC7) ships. This study addresses these gaps by analyzing the temporal and spatial changes in sea ice and navigability, considering both PC7 and OW ships, and incorporating SIM into the navigability assessment.

Numerous studies examine the feasibility and navigability of Arctic maritime transport. Some focus on the impact of weather conditions and sea ice characteristics (SIT and SIC) on navigation, utilizing models like POLARIS and AIRSS. These studies highlight the challenges posed by meteorological and hydrological risks, including strong winds, low visibility, low temperatures, and shallow water. Others emphasize the role of sea surface temperature and sea ice motion (SIM) in influencing navigability, noting that SIM can significantly affect ship heading and increase navigational risks, especially for large vessels. While research is growing on the overall impacts of climate change on Arctic maritime transport, there's a lack of comprehensive assessments that incorporate SIM and evaluate the navigability of predominantly used PC7 ships. This study aims to address these research gaps and provide a more comprehensive analysis of future Arctic shipping.

The study employs a combination of observed and simulated data to predict the navigability of Arctic shipping routes from 2023 to 2100. Four Coupled Model Intercomparison Project Phase 6 (CMIP6) climate change scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) were evaluated against observed data (SIC, SIT, and SIM) from sources such as the National Snow and Ice Data Center (NSIDC). The SSP2-4.5 scenario demonstrated the best fit with observed data and was selected for projections. The Polar Operational Limit Assessment Risk Indexing System (POLARIS) model was used to assess navigability, considering both PC7 and OW ships. The model incorporates SIC, SIT, and SIM to calculate a risk index value (RIV). A comprehensive risk index value (COMRIV) accounts for both ice conditions and SIM. A threshold of 0.15 m/s was used for SIM, assigning a negative risk value when exceeded. The A* shortest path algorithm was utilized to determine optimal shipping routes (OASR) between Rotterdam and the Bering Strait, identifying navigable areas with non-negative COMRIV values. The analysis examines navigable days (ND), navigable periods (NP), navigable area (NA), and the distribution of OASRs over time and space.

The study's key findings reveal a significant increase in Arctic navigability by 2100. Sea ice conditions are projected to worsen, with decreasing SIC and SIT across all seasons. However, the impact of sea ice motion (SIM) increases navigational risks and reduces navigability. For PC7 ships, the average annual navigable days (ND) are projected to increase from 199 in 2023 to 301 in 2100 under the SSP2-4.5 scenario. Open water (OW) ships show a less dramatic increase, from 195 to 247 NDs. Spatial analysis indicates that the Greenland Sea and Barents Sea will be year-round navigable for PC7 ships from May to December, while the NSR will become increasingly navigable throughout the year. OW ships have smaller navigable areas compared to PC7 ships, but their navigability also increases over time. The optimal Arctic shipping routes (OASR) for PC7 ships are concentrated in the Transpolar Sea Route (TSR) from August to October, shifting toward the Central Arctic in September, where SIC is lowest. Coastal areas remain important navigation routes, particularly for the Northern Sea Route (NSR). The NWP remains riskier than the NSR for the foreseeable future. The high correlation between route density and SIC (-0.95, p-value < 0.01) highlights the influence of sea ice conditions on optimal route selection.

The findings demonstrate a significant shift in Arctic navigability driven by climate change. The projected increase in navigable days and the expansion of navigable areas for both PC7 and OW ships highlight the growing potential for Arctic shipping. The shift of optimal routes toward the Central Arctic in September underscores the impact of minimal sea ice on route selection. The persistent riskier nature of the NWP compared to the NSR reveals the different levels of accessibility. These findings have substantial implications for global trade and geopolitical strategies. The increased accessibility of the NSR, in particular, will likely impact trade routes between Asia, Europe, and North America. The study's focus on PC7 ships, commonly used in the Arctic, provides a more realistic assessment than previous research that predominantly used PC6 ships. The incorporation of SIM into the analysis enhances the accuracy of navigability predictions. The results strongly suggest a need for comprehensive strategies to mitigate potential negative environmental impacts associated with increased Arctic shipping activity.

This research projects a significant increase in Arctic navigability by 2100, particularly for the Northern Sea Route (NSR), emphasizing the need for careful consideration of environmental protection and sustainable development in the region. The study highlights the growing importance of the NSR compared to the NWP and identifies optimal shipping routes shifting towards the Central Arctic as ice melts. Future research should investigate the potential negative environmental effects of increased shipping traffic, such as pollution and potential accidents, as well as the economic and logistical factors affecting the choice of vessel types and the role of icebreaker escorts.

The study relies on CMIP6 climate model projections, which inherently contain uncertainties. The selection of the SSP2-4.5 scenario as the most suitable for projection might have limitations in representing future conditions accurately. The A* algorithm used for route optimization assumes consistent sea ice conditions along the route, a simplification of real-world dynamics. The study focuses on two vessel types and doesn't account for the full diversity of vessels operating in the Arctic. The influence of geopolitical factors and potential future regulations on Arctic shipping are not directly incorporated into the model.