Gary Froyland

The ocean off the coast of Peru warms and cools, and with it the whole planet runs a fever: rains flood deserts, and tropical forests dry out. This is El Niño, the most noticeable climate oscillation after the changing seasons. For half a century, it has been described by a single number: the water temperature in a small square of ocean.

An orchestra plays without a conductor, and you hear the tempo speeding up and slowing down. All you have is a recording of the sound, not the score. Can you tell from that recording which string to pluck to make the whole orchestra play more steadily?