Beneath the surface of global commerce, a quiet reordering is underway: refineries pressed by war, sanctions, and geopolitical fracture are turning away from marine fuel in favor of more profitable or politically safer products. The shipping industry — the invisible backbone carrying nine-tenths of world trade — now faces a gathering supply constraint that few outside the industry have yet noticed. What begins as a rational calculation made inside a refinery will, if left uncorrected, arrive at the doorstep of ordinary life in the form of higher prices for nearly everything.