Observed spatial-temporal changes in the autumn navigability of the Arctic Northeast Route from 2010 to 2017

Recently, the Arctic Northeast Route (ANR), an important shipping route connecting Asia and Europe, has become more and more navigable because of the accelerating melt of sea ice in the Arctic. The exploitation of the ANR could shorten the navigational distances from North Asia to Northwestern Europe by 40% (about 2500 nautical miles) and reduce one-third (about 10 days) of the time required for maritime transport by the Royal Road, which can help to save lots of transport costs and bring large environmental benefits. It’s very important and urgent to accurately understand the changes in the navigability of the ANR for the development of the route. However, due to the lack of high-quality observed dataset, there are very few observation-based studies. Some model-based studies cannot effectively reflect the real changes in the navigability of the ANR, due to the varying degrees of the data quality issues. In this study, we applied the daily sea ice concentration product provided by the NSIDC and the reconstructed daily SMOS sea ice thickness product into the Arctic Transportation Accessibility Model (ATAM) from the Arctic Ice Regime Shipping System (AIRSS) to assess and map the daily navigation risks for open water vessels in the ANR from 2010–2017 and further analyze the spatial and temporal changes of the Autumn navigability of the route during the eight years. Assuming the navigability of a specific ice regime is affected by the sea ice conditions and the ice-breaking ability of the vessels, the ATAM model can quantify the navigability of a specific ice regime for seven different vessel types. Since the SMOS ice thickness product is more reliable in thin ice area (lower than 0.5 m), we only focus on the navigability changes of the ANR for open water vessels in this study. We found that, although the end of shipping season for open water vessels across the ANR has extended to the day of 297±4 (October 24th) since 2010 (excluding 2013), there is no significant trend in the navigability of the ANR for open water vessels in the last 8 years. Further analysis of the spatial distribution map of the navigation risk for open water vessels at the end of shipping season in different years shows that the navigability of the ANR mainly affected by the ice regime around the Eastern Siberian Sea, the Novosibirsk Islands and the Severnaya Zemlya Islands. In most years, it’s the earlier frozen ice over the three regions leading to the end of the entire ANR, in the case that most other areas are still safely navigable. We also performed detailed analysis and found that there are significant differences in the navigability changes in the three key straits for open water vessels over the ANR. The Long strait shows great inter-annual variations in the navigability, but has limit impact on the navigability of the entire route because of its late ending of the shipping season. The Sannikov Strait shows the fastest decline, but small inter-annual variations in the navigability. It is also the earliest one that ending the shipping season, and therefore has a great impact on the long-term trend of the navigability of the ANR. The intra- and inter-annual changes in the navigability of the Vlikitsky Strait are very complex. It always fluctuates dramatically, and thus has great impact on the short-term navigability of the entire ANR. In view of the complexity of the change in the ANR navigability, observed high-quality, near real-time sea ice datasets are very important for the quantification of navigation risk in the ASR.