The continuous melting of Arctic sea ice has attracted increasing interest in the potential of navigation in the Arctic route. Most existing studies use the sea ice concentration (SIC) to evaluate the sea ice condition along the route. Based on the historical sea ice data (including sea ice area) in Arctic waters, this study investigated the annual sea ice changing trend in Arctic waters, especially in summer. The overall Arctic sea ice area has shown a decreasing trend with large interannual variability in the past two decades. The navigable capacity of Sonnikov Strait follows the overall ice change of Arctic waters. Nevertheless, the sea ice in Vilikitsky Strait fluctuates wildly with significant uncertainty. The results can help merchant ships evaluate their navigation capacity in Arctic waters.
Due to the rapid economic development and the increase of human activities in the past century, global warming seems to be an inevitable trend of the climate system. In the high latitudes of the northern hemisphere, the warming of the surface is more pronounced, leading to a rapid decrease in Arctic sea ice, which makes the "Northern Sea Route (NSR)" in the northern coastal area of Russia expected to be fully opened in the not-too-long future. The Arctic Northeast Passage Route starts from Northeast Asia and passes through the Chukchi Sea, the Eastern Siberian Sea, the Laptev Sea, the Kara Sea, and the Barents Sea in the southern Arctic Ocean to the north. The main sea areas and straits that the NSR covers are present in Figure 1.
The reduction of Arctic sea ice area and even seasonally ice-free phenomenon will improve the navigability of the Arctic region. The concept of Arctic waterways is becoming a reality. The Arctic Passage consists of the NSR and the Western sea route (WSR). The NSR is from Western Europe to the Bering Strait through the five sea areas of the Arctic Ocean in Figure 1. The WSR departs from the Bering Strait and reaches North America and Canada, containing two branches. The Arctic Passage has advantages compared with the Southern Passage through the Strait of Malacca, Suez Canal, or the Panama Canal in terms of economy and efficiency, saving approximately 20% and 40% of the entire voyage distance. In addition, because the Arctic waterway is less affected by unstable factors such as pirates, the cost of escort and insurance during the voyage of ships will be significantly reduced. The opening of the Arctic waterway will greatly change the pattern of world trade, fundamentally changing the pattern of the economic circle around the Arctic Ocean dominated by Russia, North America, Western Europe, and East Asia.