Stommel Box Model: Thermohaline Circulation Bistability (2D)

The ocean's "conveyor belt" isn't a fixed pipe — it is a self-sustaining flow held up by a delicate balance between temperature and salinity, and it genuinely has more than one stable state at the same forcing. This 2D canvas simulator integrates the classic Stommel two-box ocean model live, frame by frame, with a real RK4 solver: a polar box and an equatorial box exchange heat and freshwater, and the density difference between them drives an overturning circulation. A live phase portrait plots the actual (ΔT, ΔS) trajectory and marks the model's real fixed points, computed on the fly from the current forcing — so you can watch the trajectory fall onto one of two coexisting stable circulation states, or cross the unstable saddle between them after a large freshwater pulse and stay flipped, exactly like a real climate tipping point.