Weather and Atmosphere

El Niño



Lessons and Activities

Real World Data

Background Information

Career Profiles

What do potato chip companies, zookeepers, and disaster managers have in common? It may not seem like much, but they all use ENSO data. El Niño and La Niña represent opposite extremes of the El Niño/Southern Oscillation (ENSO) cycle. ENSO refers to the cyclical changes in sea surface temperatures, rainfall patterns, surface air pressure, and atmospheric circulation that occur across the Equatorial Pacific Ocean.

Pacific Equitorial sea temperature of El Nino and La Nina
These global maps centered on the Pacific Ocean show patterns of sea surface temperature during El Niño and La Niña episodes. The colors along the equator show areas that are warmer or cooler than the long-term average. Images courtesy of Steve Albers, NOAA.(Source: ClimateWatch Magazine)

These natural climate patterns result from interactions between the ocean and the atmosphere. They affect weather around the world and may cause potato prices to jump or fall, affect diseases in zoo animals, and cause human deaths and billions of dollars in property damage.

In the 1800's, local fishermen on the Pacific coast of South America would notice a warm ocean current. Each year this warm water would arrive around Christmas-time. Referring to the birth of Christ, they named this current El Niño, which means "the boy" in Spanish. El Niño is now known to be much more than just a local current off the coast of Peru. An El Niño condition is when surface water in the Pacific, near the equator, becomes warmer and the winds blow weaker than normal from the East. The opposite condition, when the water is colder than average and winds are blowing stronger from the East, is called La Niña. El Niño and La Niña events usually occur every 3 to 5 years. These interactions of the ocean and atmosphere produce important consequences for people and ecosystems in many parts of the globe.

Pacific Equitorial sea temperature of El Nino and La Nina

Current ENSO Conditions

This meter displays how many degrees (in Celsius) the sea surface temperature in the Equatorial Pacific Ocean is above or below normal from the most recent observations (Source: Climate Prediction Center)

Weather patterns in many parts of the world are influenced by El Niño and La Niña. Humans and ecosystems can be positively and negatively affected. During the fall through spring, across the southern part of the U.S., El Niño usually causes increased rainfall and sometimes destructive flooding. During the same seasons, La Niña usually causes drier weather in the southern U.S. and colder and wetter weather in the Northwest. Even though El Niño occurs in the Pacific it often reduces the number of hurricanes that form in the Atlantic. Conversely, La Niña events tend to increase the number of hurricanes (Source: PMEL).

Food production is impacted by ENSO. Changes in ocean temperatures and currents that happen during El Niño impact marine life. This can impact people who make a living fishing and consumers who depend on certain fish for food. Agriculture is very dependent on climate and ENSO's affect on rainfall and temperature have important impacts on food production.

Education Connection
ENSO provides teachers with the opportunity to have students discover ways that the oceanic and atmospheric systems interact and how those interactions can impact ecosystems and human society. The resources in this Collection can be used to help learn about; the basics of ENSO, the inter-relationship of Earth systems, the impacts of these interactions, and how to use and analyze data. These resources can be used to teach students how scientists study the complexity of the Earth's systems and how better El Niño/La Niña forecasts can benefit agriculture (including potato chip companies) and fishing, as well as zookeepers and disaster managers.

Adapted from materials provided by Climate Prediction Center and National Centers for Environmental Prediction.

El Nino from satellite.
Can We Blame El Nino?

October 2009 (Climate Watch)
For years, people have been pointing to El Niño as the culprit behind floods, droughts, famines, economic failures, and record-breaking global heat. Can a single climate phenomenon really cause all these events?... Read More

2010 Winter outlook, La Nina
Winter of Extremes in Store for U.S. as La Niña Strengthens

October, 2010 (NOAA)
Winter 2010, a moderate to strong La Niña will be the dominant climate factor influencing weather across most of the U.S.... Read More

El Nino linked to 1918 flu pandemic
1918 Pandemic and El Nino

February, 2010 (Office of the Public Health Service Historian)
A new NOAA-funded study suggests a possible link between one of the strongest El Nino's of the 20th century and the 1918 flu pandemic.... Read More