El Nino FAQs

El Nino is the warm phase of the El Niño-Southern Oscillation cycle (ENSO), a naturally occurring climate pattern in the tropical Pacific Ocean. During an El Nino event, sea surface temperatures in the central and eastern Pacific become warmer than average, while trade winds weaken. El Nino is typically characterised by ocean temperatures in the eastern equatorial Pacific rising 0.5°C or more above average. These changes can drive widespread climate impacts, including droughts, increased rainfall and flooding and shifts in hurricane activity.

What is the difference between El Nino and La Nina?

El Nino and La Nina are opposite phases of the same climate cycle, known as ENSO. During El Nino, weaker trade winds allow warmer water to spread across the central and eastern tropical Pacific. During La Niña, stronger trade winds push warm water towards Asia, and the same region runs cooler than average. As a result, weather patterns during El Nino and La Nina often have opposite effects in many parts of the world, with regions that are wetter during one phase often becoming drier during the other.

How often do El Nino and La Nina occur?

El Nino and La Nina events occur irregularly, on average every two to seven years. Events typically last around nine to twelve months, although some episodes can last for as long as two years. Following an event, the Pacific Ocean often transitions through a neutral phase before another ENSO phase develops. Transitions between El Nino and La Nina typically occur over a period of one to six months. While El Niño and La Niña can sometimes occur back-to-back, they are often separated by periods of neutral conditions. El Niño events generally occur slightly more frequently than La Niña events.

Why is it called El Nino?

The name El Niño was given by fishermen on the Pacific coast of South America, who noticed unusually warm ocean waters appearing every few years around Christmas. These warmer waters reduced fish catches, negatively affecting the food supply of communities in coastal Peru. In reference to the Christ Child, they named the phenomenon, El Niño, which means "the boy" in Spanish.

Which regions are impacted by El Nino?

El Nino affects countries around the world, but its impacts are often the strongest in tropical regions, particularly in parts of Africa, Latin America and South and South-East Asia that are particularly vulnerable to natural hazards.

Are there any benefits of El Nino?

El Nino can have some beneficial effects in certain regions. Parts of the southern United States and South America, often experience increased rainfall during El Nino events, which can help replenish water supplies and support agriculture. El Nino can also supress Atlantic hurricane activity, by increasing wind shear over the Atlantic Ocean, making it more difficult for hurricanes to develop and strengthen. Additionally, parts of North America, often experience milder winters during El Nino, which can lower the risk of cold-related illnesses.

Is El Nino caused by climate change?

No, El Nino is not caused by climate change. El Nino is a naturally occurring phase of ENSO climate pattern. However, climate change may influence how El Nino events affect weather and climate. Research on whether climate change is altering the frequency or intensity of El Niño events is ongoing.

What is meant by the term "Super El Nino"?

"Super El Nino" is not an official term, rather, it is an informal term commonly used to describe a very strong El Nino event. While an El Nino is declared when sea surface temperatures in parts of the Pacific are at least 0.5°C above average, a "Super El Nino" typically refers to when sea surface temperatures rise by 2°C or more above average. The World Meteorological Organization (WMO) officially classifies ENSO events as weak, moderate, strong or very strong. According to WMO forecasts, the current El Nino is expected to intensify into a very strong event by the end of the year.

Sources:
Understanding El Niño & ENSO | National Oceanic and Atmospheric Administration
El Niño and La Niña | National Oceanic and Atmospheric Administration
El Niño Southern Oscillation (ENSO)