El Niño events, in which warmer than usual sea surface temperatures occur in the equatorial Pacific Ocean, are known to have a major influence on weather patterns worldwide. To help improve predictions, Yu and Kim categorized the ways in which certain types of El Niño events evolve. They focused on an El Niño known as the central Pacific (CP) type, in which sea surface warming occurs mainly in the central Pacific Ocean rather than in the eastern Pacific, where most common El Niño sea surface warming occurs. The two types of El Niño events have different effects on weather patterns and may respond differently to global warming. The CP type has occurred more frequently in recent decades.