What is EL Nino?

El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean. 

In the Pacific Ocean, during normal conditions, trade winds blow west along the equator. It takes warm water from South America towards Asia and replaces it. Then cold water rises from the depths — a process called upwelling. El Niño and La Niña are two opposing climate patterns that break these normal conditions. Scientists call these phenomena the El Niño-Southern Oscillation (ENSO) cycle. El Niño impacts weather systems around the globe, triggering predictable disruptions in temperature, rainfall, and winds.

How do El Niño and La Niña occur?

El Niño and La Niña events are natural occurrences in the global climate system resulting from variations in ocean temperatures in the Equatorial Pacific. In turn, changes in the atmosphere impact the ocean temperatures and currents. The system oscillates between warm (El Niño) to neutral or cold (La Niña) conditions.

Is El Niño caused by climate change?

El Niño events are not caused by climate change, rather they are naturally-reoccurring phenomena that have been going on for years. The phenomenon typically occurs every two to seven years. The 2015-2016 El Niño was called a “super” El Niño, the worst in 15 years. Scientists believe these phenomena may be becoming more intense and/or more frequent as a result of climate change, although the exact causes remain unclear. 

What are the global impacts of El Nino?

While El Niño and La Niña do impact global climate patterns; however, they neither affect all regions nor do their impacts in a given region the same. In many locations, especially in the tropics, La Niña (or cold episodes) produces roughly the opposite climate variations from El Niño. For instance, parts of Australia and Indonesia are prone to drought during El Niño but are typically wetter than normal during La Niña. 

The impacts of each La Niña event are never exactly the same. They depend on the intensity of the event, the time of year when it develops, and the interaction with other climate patterns.

Can we predict El Niño?

The onset of El Niño and La Niña several months to a year in advance can often be predicted due to modern climate models and observations data (which includes sensors on satellites and ocean buoys), which constantly monitor changing conditions in the ocean and atmosphere.