An Ethiopian farmer looks at the sky and waits for rain. If it doesn't come, fields dry up and children go hungry. Previously, no one could say in advance what the season would be like. Now scientists have found a clue thousands of kilometers away: in the Pacific Ocean.

The Pacific Ocean acts like an orchestra conductor. When its waters off the coast of South America become colder than usual, that is the La Niña phase. The signal travels through the air like a wave of the baton, and a year later it reaches Ethiopia. There, it disrupts the rains: the colder the ocean, the drier the season will be. Scientists tested this connection and confirmed that it is real, not a coincidence.

Today, looking at a map of the Pacific Ocean, a meteorologist sees not just a cold patch. He sees a warning that can help Ethiopia face a dry year prepared.