El Niño is a climate pattern that originates in the Pacific Ocean along the equator and impacts weather all over the world. It is the warm phase of the El Niño-Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific, including the area off the Pacific coast of South America. The term "El Niño" means "The Child" in Spanish, which references the baby Jesus, whose birth is celebrated on Christmas Day, near the time when the warming of the waters is often noticed.
El Niño is characterized by the unusual warming of surface waters in the eastern tropical Pacific Ocean. During an El Niño event, westward-blowing trade winds weaken along the Equator, causing warm surface water to move eastward along the Equator, from the western Pacific to the coast of northern South America. El Niño events are defined by their wide-ranging teleconnections, which are large-scale, long-lasting climate anomalies or patterns that are related to each other and can affect much of the globe.
El Niño can have significant impacts on weather patterns around the world. For example, it can cause droughts in some areas and flooding in others. It can also affect ocean currents, which can impact marine ecosystems and fisheries. La Niña is the "cool phase" of ENSO and is a pattern that describes the unusual cooling of the regions surface waters. It has the opposite effect of El Niño, with stronger than usual trade winds pushing more warm water toward Asia and increasing upwelling off the west coast of the Americas, bringing cold, nutrient-rich water to the surface.
