Every few years, a warm current called El Niño appears in the tropical Pacific. It is like an uninvited guest that turns a house upside down: causing droughts in some places and floods in others. Scientists want to warn of its arrival in advance, but the ocean does not give up its secrets. The cause of El Niño is not in a single location but in how different parts of the ocean communicate, even when thousands of kilometers apart. Conventional computer models only see neighbors, like a person who hears only the neighbors next door but does not know that someone across town opened a faucet and changed the pressure in the pipes.

Scientists gave such a program a map of the ocean and let it decide which points are strongly connected and which are weakly connected. It turned out that for a one-month forecast, it predicts El Niño more accurately than previous models: a correlation of 0.9867 versus 0.94. For three months ahead, it is also better: 0.8936 versus 0.8742. This is like a resident who finally learns about the faucet across town not from a wet ceiling but from a slight drop in water pressure. However, for six months ahead, the new model still lags because it lacks data on how much heat is stored in the upper ocean layer. But the scientists already plan to add that data and hope the model will then warn of the ocean's whims even earlier.