Every few years, the Pacific Ocean rearranges itself: warm water from the east flows toward the coasts of South America, and weather goes haywire for six months. This is El Niño, and its arrivals cannot be predicted precisely, even though there is a rhythm to them. A model with 930 variables shows that noise is to blame—random gusts of wind acting like an invisible conductor.

Below the critical threshold, the system's resonances line up in a triangular lattice, like the sounds of an out-of-tune instrument that never coalesce into a melody. Above the threshold, they form parabolas, where each successive harmonic decays faster than the last. This is like an orchestra that has finally heard its conductor: the musicians play the same theme, but each one lags or rushes a little.

The phase of the oscillations drifts, like a pendulum pushed out of sync. Even if the amplitude remains stable, the timing of the next peak becomes increasingly uncertain. That is why El Niño does not arrive by the calendar: its clock is smeared by noise.

The same approach applies to other stochastic oscillators, from climate models to biological rhythms. Wherever noise does not just interfere but gives birth to order, one can look for such resonant structures. The ocean remains the ocean, but now its music has been written down in notes.