The history of El Niño and La Niña

As I’ve been stating in previous articles, ocean temperatures near the West Coast of South America and the Equatorial regions are warming up. A new El Nino event was declared in June and is expected to intensify in the coming months. According to the projections from many forecast climate models, the peak of this El Niño is likely to surpass the previous record-holder by “truly, a mind-blowing margin.” The U.S. National Oceanic and Atmospheric Administration (NOAA) provided a four in five chance of this “very strong” event developing by the end of the year, with El Niño conditions likely to persist until at least the spring of 2027.

El Niño and La Niña are opposite phases of a natural climate pattern known as the El Niño-Southern Oscillation (ENSO). Originating in the tropical Pacific Ocean, ENSO is one of the most influential climate systems on Earth. Both events will often affect weather patterns, ecosystems, agriculture, and economies around the globe. Although scientists have only studied ENSO in detail for about the last 150 years, historical records and long-time evidence of coral reefs, tree rings, lake sediments, and ice cores reveal that ENSO has existed for at least thousands of years, probably much longer.

The name El Nino, means "The Little Boy" or "Christ Child" in Spanish. It was first used by fishermen along the South American coasts of Peru and Ecuador during the 1600s. They noticed that around Christmas, the normally cold waters of the eastern Pacific occasionally turned unusually warm. This warming often led to poor fishing seasons as it reduced the nutrient-rich upwelling that supported abundant fish populations. Because the warming often appeared near Christmas, the fishermen named the phenomenon after the Christ Child.

The opposite phase, La Nina, meaning "The Little Girl" in Spanish, was not recognized until the 1970s. Prior to the new name, scientists originally referred to it as the "anti-El Niño." During La Niña events, the stronger-than-normal trade winds increased the upwelling of cold, nutrient-rich water along the west coast of South America, which would cool the central and eastern tropical Pacific Ocean. By the late twentieth century, the term "La Niña" became widely accepted as researchers gained a better understanding of ENSO.

Scientific study of El Nino began in the late nineteenth century. In the early 1900s, British meteorologist Sir Gilbert Walker investigated unusual changes in atmospheric pressure across the Pacific and Indian Oceans while searching for ways to predict the Indian monsoon. Walker discovered a repeating pattern of pressure changes that became known as the Southern Oscillation. Although he did not initially connect it to the warming of Pacific waters, his work laid the foundation for understanding changes in sea-surface temperatures.

During the 1960s, Norwegian-American meteorologist Jacob Bjerknes determined that El Nino and the Southern Oscillation were closely linked. He showed that weakened trade winds allow warm surface water to move eastward across the Pacific, altering atmospheric circulation and changing weather patterns around the world. This discovery established the modern concept of the El Niño-Southern Oscillation.

Since then, improvements in satellites, ocean buoys, and computer models have greatly enhanced scientists' ability to monitor and predict ENSO events. The Tropical Atmosphere Ocean (TAO) buoy array, established in the 1980s, provides continuous measurements of sea surface temperatures, winds, and ocean conditions across the equatorial Pacific, giving forecasters early warning of developing El Niño or La Niña conditions.

Several El Niño events have had profound global impacts. For example, the 1982–1983 El Nino was one of the strongest ever recorded, causing devastating floods in Peru and Ecuador, severe droughts in Australia and Indonesia, and widespread economic losses. The 1997–1998 El Niño was even more powerful, contributing to billions of dollars in damage worldwide through floods, droughts, wildfires, and powerful storms. More recently, the 2015–2016 El Nino brought record global temperatures, widespread coral bleaching, and major disruptions to agriculture and water supplies.

Strong La Niña events have also influenced weather patterns. The 1973–1976 La Niña contributed to increased Atlantic hurricane activity and severe drought in parts of the United States. The prolonged 2020–2023 "triple-dip" La Niña, which lasted for three consecutive winters, influenced weather worldwide by increasing flooding in Australia and parts of Asia while contributing to persistent drought across portions of the western United States and South America.

El Nino and La Nina is one of the most closely monitored climate phenomena because of their widespread effects on global weather. Advances in climate science have transformed ENSO from a mysterious oceanic event observed by fishermen into one of the world's most important tools for seasonal weather forecasting. Sea-surface temperature forecasts are also used to help predict future snowfall totals for North Idaho.

In terms of our local weather, only 0.01 inches of rain fell at Cliff Harris’s station in July. At the Spokane International Airport, no measurable rainfall has been recorded this month. More dry and very warm weather is expected into early August. However, with the rapid warming of sea-surface temperatures, we may see some moisture from the southwesterly regions later in August and September. Thanks to a potentially strong El Nino in the coming months, we may be talking about an “open winter” with below normal snowfall. Stay tuned.

• • • 

Contact Randy Mann at [email protected].