Every year, an El Niño can occur in the Pacific Ocean: the water off the coast of South America becomes warmer than usual, and this changes weather across the planet. In 2021, two tools that predict this phenomenon a year in advance gave different answers. One said, "No El Niño." The other countered, "Yes, and a strong one."
The first tool tracks how temperatures at different points in the ocean change together. If they start moving in sync, like dancers in the same rhythm, that is a signal of an upcoming El Niño. In 2021, no such signal appeared. The second tool looks at temperature records at a single location and assesses how tangled they are. If the records become complex, like a long story with no repetition, that too is a harbinger. And indeed, it showed high complexity.
So scientists concluded that in 2022, El Niño would most likely not happen. But if it did start, it would be strong. And so it happened that the year began with a question mark: should we prepare for drought or just normal weather?
In 2012, when most forecasting centers expected El Niño with 75% probability, the climate network method had already predicted its absence in late 2011—and turned out to be right. This was one of the first public successes of the network approach.