1. Introduction

The Arctic, long considered a largely inaccessible and frozen frontier, has undergone dramatic environmental transformations over the past 30 years, driven predominantly by anthropogenic climate change(IPCC, 2023). Sea ice extent in the Arctic Ocean has declined at a rate of approximately 13% per decade in September since satellite monitoring began in 1979, culminating in record lows in recent years(Serreze and Stroeve, 2015). This reduction in sea-ice coverage has far-reaching implications, including altered atmospheric-oceanic feedbacks, ecosystem disruption, and the unprecedented opening of northern maritime routes(Donald and Jacqueline, 2009).

One significant consequence of diminishing sea ice is the opening of new maritime routes through the Arctic Ocean, potentially revolutionizing international shipping logistics by shortening distances between major markets in Europe, Asia, and North America(Chen et al., 2024). The three primary routes of interest include the Northern Sea Route(NSR; along Russia's northern coast), the Northwest Passage(NWP; through the Canadian Arctic Archipelago), and the emerging Transpolar Sea Route(TSR) across the central Arctic basin(Smith and Stephenson, 2013).

Despite these advantages, using the Northern Sea Route presents several complex challenges. While Arctic ice cover is decreasing, navigational availability and the risks ice poses to vessels during the winter and summer seasons still limit freedom of navigation. This study has three primary objectives: (1) to analyze observed changes in sea ice extent and navigable days from 1990 to 2024; (2) to analyze vessel traffic using the Northern Sea Route using AIS data and the NSR permit database; and (3) to analyze the economic benefits and environmental risks associated with increased shipping volume. By integrating climatological, oceanographic, and navigational data, this study provides an integrated framework to support sustainable Arctic shipping governance in the face of accelerating climate change.

2. Methods

2.1 Data Sources

Satellite-derived sea ice concentration and thickness data were obtained from the National Snow and Ice Data Center(NSIDC) and the European Space Agency’s Climate Change Initiative, providing high-resolution observations from passive microwave sensors and altimeters(NSIDC, 2025;ESA, 2025). Surface air temperature and sea surface temperature data were sourced from the Coupled Model Intercomparison Project Phase 6(CMIP6) multi-model ensemble, incorporating historical simulations and near-term projections(Notz et al., 2020;Wei et al., 2020;Chen et al., 2021;Zhao et al., 2024). Based on this data, the navigable months were predicted for each air pollution scenario.

To examine long-term Arctic shipping trends, this study integrates two primary datasets. First, vessel data from the Protection of the Arctic Marine Environment(PAME) Working Group of the Arctic Council were utilized(PAME, 2025). The Arctic Ship Traffic Database(ASTD) provides traffic statistics based on AIS records for 2013–2024. This dataset covers vessel type, flag state, distance sailed, and number of transits across all Arctic waters and forms the foundation for temporal trend analysis between 2013 and 2024.

Second, verified transit approval data from the Northern Sea Route portal managed by the Russian Federal State Enterprise Glavsevmorput under Rosatom were used(NSR, 2025). The NSR database provides records of ships officially authorized to navigate through Russian Arctic waters from 2021 onward. Data before 2021 are not publicly available, and incomplete entries remain a limitation of the NSR platform. The dataset for 2025 reflects updates as of December 10, 2025; missing or unverifiable entries between 2021–2024 are labeled as “No Information”.

This methodological integration of PAME’s AIS data (2013– 2024) and NSR permit data (2021–2025) allows both global and route-specific assessments of Arctic vessel operations. Given that no comparable permits or open-access database exists for the Canadian Arctic sector(NWP), the empirical scope of the analysis limited to publicly available Russian NSR data.

2.2 Analytical Framework

Temporal trends in sea ice extent, thickness, and seasonal duration were visualized using NSIDC database to identify significant changes over the 35-year span. Spatial patterns of ice retreat were mapped to delineate evolving navigable corridors.

Navigable windows along the NSR, NWP, and TSR were determined by applying ice thickness of less than 30cm compatible with the Polar Class 7 vessel operational limits, following guidelines from the International Maritime Organization’s Polar Code(IMO, 2016;IMO, 2009). Sensitivity analyses considered more restrictive thresholds aligned with higher Polar Class vessels.

Shipping distance and time savings were quantified by comparing Arctic route metrics against traditional routes like the Suez and Panama Canals using maritime routing software. Hazard assessments incorporated occurrence frequency of hazardous weather events, iceberg presence, and environmental sensitivity indices adapted from Arctic risk frameworks(Xu et al., 2021).

The vessel data used in this study originated from the NSR database, where ship transit information along the Northern Sea Route is publicly available. The Northern Sea Route operates under Russian jurisdiction, requiring prior approval for vessel transit. No comparable public transit approval or vessel tracking system is available for the Canadian Arctic region, restricting study scope to NSR data.

By analyzing NSR data, we investigated the characteristics of vessels using the Russian NSR, categorizing them as follows:

Flag State: We examined the distribution of flag states of vessels using the NSR. Since the NSR is Russian territory, we distinguished between Russian and non-Russian flag ships and then examined the distribution of flag states for non-Russian vessels. This analysis allowed us to understand the actual status of foreign vessels using the NSR.

Ice Class: We analyzed the distribution of ice classes for non-Russian flag ships to determine the actual distribution of ice classes used on the NSR and assess the ice classes required for NSR use.

Vessel Type: We analyzed non-Russian flag ships by vessel type and classified them by type to investigate their use of the NSR, thereby understanding the logistics landscape.

To assess vessel ice navigation capability, the classification framework of the Russian Maritime Register of Shipping(RMRS) was applied, which distinguishes Non-Arctic (Ice 1-3) and Arctic (Arc 4-9) vessel classes based on hull strength, ice thickness tolerance, and operational viability. The classification system facilitates quantitative assessment of vessel operability in Arctic ice conditions(RMRS, 2025). The following Table 1 summarizes RMRS ice classifications and definitions from the Rules for the Classification and Construction of Sea-Going Ships, Part I, §2.2.3. This classification system supports detailed operational analysis of vessels navigating the Russian Arctic, emphasizing differences in international fleet participation and ice navigation capabilities.

Table 2 shows the Polar classes of the Polar code. While classification rules are based on specific criteria, the Polar code classifies Polar classes based on abstract criteria. As the number of classes increases, the navigation area decreases.

3. Results

3.1 Sea Ice Decline and Seasonal Changes

Analysis of satellite data from 1990 to 2024 found a statistically significant decline in Arctic sea ice extent at an average rate of 12.8% per decade, consistent with previous findings by Serreze and Stroeve(2015). The maximum ice extent decreased noticeably during summer months, with minimum September ice extent reducing from approximately 6.5 million km² in the early 1990s to 4.4 million km² in recent years(Fig. 1, Fig. 2). Concurrently, sea ice thickness diminished by up to 32%, and the ice-free season extended by an average of 2.5 days per year across the Northern Sea Route.

3.2 Expansion of Navigability Windows

Applying ice concentration thresholds relevant to Polar Class 7 vessels, the Northern Sea Route’s ice-free period increased from an average of 60 days per year in the early 1990s to more than 130 days by 2024(Fig. 3). The Northwest Passage showed a more variable trend but also exhibited increases in navigable days, expanding by approximately 12 days per decade. The Transpolar Sea Route, historically inaccessible for commercial shipping, demonstrated emerging windows of open water in late summer months, with sporadic navigation possibilities evident after 2015.

Projected years of ice-free September and average navigable months for NSR/NWP under CMIP6 scenarios are described in Table 3. Under the high-emission scenario SSP5-8.5, the Arctic Ocean is projected to experience ice-free September conditions by 2050, with the Northern Sea Route extending to 8~9 months of annual navigability and the Northwest Passage to 6~7 months. The intermediate emissions pathway SSP2-4.5 delays ice-free September conditions to approximately 2070, corresponding to 4~5 navigable months on the NSR and 2~3 months on the NWP. Under the stringent low-emission scenario SSP1-2.6, ice-free September conditions are not projected to occur until after 2100, with the NSR maintaining only 2~4 months of navigability and the NWP remaining largely inaccessible at less than 2 months annually. These projections underscore the critical relationship between cumulative greenhouse gas emissions pathways and the long-term viability of Arctic routes as commercial corridors.

3.3 Shipping Traffic Trends

Table 4 is derived from the Arctic Ship Traffic Database (ASTD) managed by the Protection of the Arctic Marine Environment(PAME) Working Group of the Arctic Council, covering the period 2013–2024(PAME, 2025). AIS-based analysis indicates annual figures of vessel activity classified by ship type. Vessel classes shifted towards higher Polar Class certifications, reflecting adaptation to evolving ice conditions. Crude oil tankers and Gas tankers, in particular, have seen their share increase over the past decade. However, the results were influenced by an increase in the share of tanker ships navigating NSR as Russia exported Arctic crude oil and liquefied natural gas to meet China's growing energy needs under geopolitical and economic conditions(Humpert, 2025).

The following analysis analyzes the official NSR database (2021-2025) operated by Glavsevmorput, a Russian state-owned enterprise(Rosatom). This database contains information on applications for passage through Rosatom and, when vessels transit the NSR, on the list of applications and permits received. Unlike AIS data, which is automatically collected, NSR records are published on the website following an administrative process (application → approval → website publication). This creates statistical discrepancies in AIS data, which includes all information on the Northern Sea Route but not on the Russian NSR.

This statistical discrepancy is not due to data inconsistencies, but rather to fundamental differences in data sources. PAME's ASTD dataset covers all Arctic shipping activity, while the NSR portal only publishes information on vessels that have received administrative approval to navigate within Russian waters. In other words, PAME data provides comprehensive traffic information based on AIS, while the NSR database reflects information on applications for passage permits. Therefore, the differences in the figures shown in Table 4 are not statistical errors, but are a direct result of differences in the sections using the North Pole, data collection methods, and the need for passage permits.

Table 5 is based on verified vessel data from the Russian NSR portal(https://nsr.rosatom.ru/) for the period 2021–2025, which contains detailed information on vessels officially authorized to transit the route. During this timeframe, approximately 90% of ships were Russian-flagged, while foreign-flagged ships accounted for around 10% of total traffic. The leading foreign registries included Liberia, Hong Kong, Panama, Cyprus, and the Marshall Islands, reflecting the prevalence of open registries (Flags of Convenience) and their commercial flexibility. The war between Russia and Ukraine in 2022 temporarily reduced the number of ships using the NSR, but has since returned to average levels.

As shown in Table 6, analysis of ice class distribution among foreign-flagged vessels reveals that Arc 7-class ships consistently dominated throughout the 2021 - 2025 period, with 26 - 31 vessels annually and a total of 135 transits. These are primarily LNG and crude oil tankers equipped for ice-strengthened navigation in the western and central NSR sectors.

In contrast, Non-ice class vessels (those without ice classification) increased sharply after 2023, rising from only 4 vessels in 2021 to 43 in 2025. This trend reflects the reduction in summer sea ice coverage and suggests significantly broader accessibility for conventional merchant fleets that lack ice-strengthening capabilities. The category “No information” represents missing official data for some years (2021–2024) on the NSR portal.

Table 7 analyzes the types of vessels using the NSR, targeting non-Russian vessels. The overwhelming majority of foreign-flagged vessels transiting the NSR were LNG tankers. A total of 193 operations were confirmed over the five-year period (2021-2025), accounting for 34.9% of all NSR operations during that period. Bulk carriers (61 operations), crude oil tankers (48 operations), and general cargo ships (48 operations) followed.

A notable correlation was found between LNG tankers and Arc 7-class vessels (see Table 6), indicating an increase in the number of foreign-flagged LNG tankers. This suggests that vessels related to the Russian Yamal LNG Project, in collaboration with Russian companies, are increasingly using the NSR. Furthermore, as LNG demand grows, the number of NSR operations is expected to increase.

Furthermore, the increased use of general cargo ships since 2023 demonstrates the potential for transporting a diverse range of cargoes. Additionally, three research vessels were identified in 2025, which are unique in that they are conducting research with Russian permission in Russian territorial waters, going beyond traditional maritime logistics.

3.4 Route Efficiency and Environmental Risks

Table 8 presents a comparative overview of key indicators reflecting the impact of Arctic sea ice decline on commercial navigation and associated environmental risks over the past three decades. Notably, the September sea ice extent has decreased from an average of 6.5 million km² in the 1990s to 4.4 million km² in the 2020s, marking a reduction of approximately 32%. This substantial retreat of sea ice has led to a dramatic increase in the number of navigable days along the NSR, from an average of 60 days per year in the 1990s to nearly 130 days in the 2020s, an increment of about 117%.

From a logistics perspective, utilization of the NSR and other polar shipping routes has resulted in a distance reduction of up to 40% (about 4,000 nautical miles) for voyages between Asia and Europe, translating into fuel savings estimated at 20–30%. The frequency of commercial transits in the Arctic region has surged from around 80 voyages annually in the 1990s to more than 570 voyages per year in the 2020s, a 713% increase.

However, while these changes indicate significant gains in route efficiency and commercial opportunity, Table 8 highlights escalating environmental and safety risks. The reduction in sea ice increases the likelihood of extreme weather dynamics, iceberg hazards, and concentrated vessel traffic in ecologically sensitive zones. Consequently, such shifts necessitate robust management frameworks for sustainable Arctic navigation, balancing economic benefits against enhanced environmental and operational risks.

4. Discussion

The continuous decline of Arctic sea ice has fundamentally transformed the maritime landscape of the region, enabling broader and spatially diverse navigation on the principal shipping routes. By adopting a dual-source approach that combines AIS-derived observational data with NSR administrative permit records, provides clarity on the full spectrum of vessel activity and trends by jurisdiction. The notable increase in non-ice class vessel operations since 2023 suggests that seasonal reductions in sea ice are lowering infrastructural entry barriers, thereby accelerating shifts in fleet composition and operational risks.

Expanded summer navigation, greater international fleet participation, and the diversification of vessel operations (notably the increasing presence of research and technical support vessels) exacerbate threats to the Arctic’s fragile ecosystems, elevate the risk of maritime incidents, and challenge conventional search and rescue preparedness. The balance between improving route efficiency, expanding commercial opportunities, and increasing environmental liabilities remains central to shaping sustainable Arctic maritime governance.

Integrating real-time AIS traffic data, satellite-based ice metrics, and climate model projections can facilitate adaptive decision-making and strategic route planning. Policymakers should prioritize a balance between economic efficiency, robust safety standards, and ecological management to address the dual imperatives of sustainable development and risk mitigation. As climate change continues to redefine the Arctic, effective policy frameworks must be flexible, comprehensive, and based on the latest scientific observations and risk assessments.

5. Conclusion

Over the past three decades, climate change has led to a decline in Arctic sea ice, transforming the Arctic region from a remote frontier into a global maritime trade hub. Recent analysis of vessel transit records reveals over 600 annual commercial passages, alongside increased diversification in vessel types and flag states. The NSR currently serves as major Arctic shipping route, with significantly longer ice-free periods and an unprecedented increase in vessel transits. And the number of non-ice class vessel operations is also increasing rapidly.

This transition brings significant economic opportunities, such as shorter transport distances and costs, but also serious challenges, such as environmental protection and maritime safety. Therefore, coordinated efforts between Arctic countries and stakeholders are essential to ensure sustainable growth in Arctic shipping and to achieve a balance between economic development and ecological integrity. As the Arctic maritime boundary shifts under rapidly changing climate conditions, continued interdisciplinary research and international cooperation are crucial.

This study analyzed over 30 years of climate data, 12 years of AIS-based vessel traffic data, and 5 years of NSR administrative permit records. However, the period for in-depth analysis of NSR transit information was inevitably restricted due to limitations in the availability of meaningful data. In particular, while the NSR data is complete through 2025, it lacks complete information prior to 2024, making absolute comparisons difficult. Going forward, we plan to enhance this paper by accumulating data from 2025 and beyond, and then comparing and analyzing the complete data. Future research will expand the scope the study by integrating more diverse datasets and extending the analysis period. Furthermore, we aim to enhance the effectiveness of the study by expanding the analytical framework to encompass not only climate change and vessel transit data, but also geographic, political, and economic dimensions.