The El Niño/Southern Oscillation, otherwise known as ENSO, is a cycle of climatic warming and cooling patterns occurring in the equatorial zone of the Pacific Ocean. While this cycle varies in length, it typically takes place over a 2-7 year period. The cycle consists of two distinct climatic events, La Niña and El Niño, and a neutral period where neither occurs.

During La Niña, the east-to-west trade winds that are normally present intensify, moving warm surface water from the eastern Pacific to the western Pacific. Deeper, cooler water moves up to replace it, resulting in warmer surface waters in the western Pacific and colder surface waters in the eastern...