Trans-Arctic route feasibility on a pan-Arctic grid under bathymetric and sea-ice constraints

TL;DR

The paper addresses the feasibility of trans-Arctic shipping under bathymetric and sea-ice constraints using a basin-scale offline routing framework. It builds a 0.5-degree pan-Arctic grid, fuses GEBCO 2024 bathymetry with CMEMS 2018 sea-ice reanalysis, and applies A* pathfinding to a Europe–Asia OD pair to quantify route availability and distance inflation relative to a great-circle baseline. Key findings show a ~10% distance penalty for sea-only routing, modest impact of depth constraints at this resolution, and strong seasonal control by sea ice, with late-summer corridors incurring ~20–25% extra distance; joint depth–ice constraints can completely sever connectivity in the tested season. The framework serves as a basin-scale screening tool for Arctic routing and provides a baseline for forecast-driven, multi-objective routing studies that incorporate higher resolution and time-dependent forcing.

Abstract

Climate driven reductions in Arctic sea ice have renewed interest in trans Arctic shipping, but adoption remains limited by basic questions of route feasibility, safety and excess distance. Existing studies mostly compare idealised great circle shortcuts or use full weather routing systems, leaving a gap for simple basin scale diagnostics on realistic bathymetry and sea ice. We develop an offline graph based framework on a 0.5 degree pan Arctic grid that combines GEBCO 2024 bathymetry with a summer 2018 Arctic sea ice reanalysis from the Copernicus Marine Environment Monitoring Service (CMEMS). An A* pathfinding algorithm is applied to a canonical Europe Asia origin destination pair to quantify route availability and route length inflation relative to a great circle. Enforcing sea only feasibility increases route length by about 10 percent before depth and ice constraints are applied. Depth thresholds representative of under keel clearance (hmin = 20-50 m) remove up to roughly 15 percent of the sea mask but preserve a trans Arctic connection for hmin = 20 m. Summer sea ice exerts a strong seasonal control: continuous ice safe routes emerge only from mid August, with distances inflated by roughly 20-25 percent even in late summer. When depth and ice constraints are imposed jointly, only about 75 percent of sea cells remain safe and no continuous joint safe trans Arctic route exists in the tested season. The framework provides a basin scale screening tool for Arctic shipping and a baseline for forecast driven, multi objective routing studies.

Figures (14)

• Figure 1: (a) GEBCO 2024 bathymetry coarsened to a $0.5^{\circ}\times0.5^{\circ}$ routing grid over the Arctic corridor (40--85$^{\circ}$N, 20$^{\circ}$W–180$^{\circ}$E). (b) Derived land/sea mask and connected sea components; the largest sea component links the North Atlantic and North Pacific, while smaller ones are enclosed shelf seas and fjords.
• Figure 2: Sea-only A* route (red) between the canonical origin--destination pair overlaid on the GEBCO-based $0.5^{\circ}$ bathymetry. The route remains within the static sea mask and follows deep-water pathways along the Arctic margin.
• Figure 3: (a) Bathymetry along the baseline sea-only route as a function of cumulative distance. (b) Depth histograms for all sea cells in the corridor (blue) and for routed cells (orange); the route samples predominantly deep water and only briefly crosses shallow shelves.
• Figure 4: Sea-only A* route (red) over GEBCO 2024 bathymetry on the $0.5^{\circ}$ grid, with selected isobaths. The path tracks the Arctic shelf break and remains mostly in deep water even without explicit depth constraints.
• Figure 5: Effect of minimum depth $h_{\min}$ on the fraction of depth-safe sea area (blue, left axis) and the number of depth-safe components (orange, right axis). Markers indicate whether the canonical origin and destination lie in the same component (route possible) or not.