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