A Brief History of Understanding
In the late 19th century, Victor Eguiguren of the University of Piura, Peru, first mentioned the “El Niño” phenomenon in academic literature, but it was regarded at the time as only a local event off the Peruvian coast. The true leap in understanding came in the mid-to-late 20th century:
Jacob Bjerknes discovered the physical link between El Niño and the Southern Oscillation, first proposing the ocean-atmosphere coupling mechanism that laid the foundation of ENSO theory.
The 1982–83 super El Niño went unpredicted, galvanizing the global climate community to invest heavily in ENSO research. NOAA launched the TAO buoy array, enabling real-time equatorial Pacific monitoring.
The 1997–98 event was successfully predicted 6 months in advance, marking the operationalization of ENSO forecasting. Climate model accuracy has steadily improved since, and the 2015–16 event was accurately forewarned by multiple agencies.
Major Events Timeline
“The Great El Niño”
One of the earliest well-documented super El Niño events. Rainfall in northern Peru reached more than 10 times the normal level, while devastating famines struck India and China (the “Dingwu Famine”). Estimated global death toll exceeded 20 million, though the exact causal link between the famines and El Niño remains academically debated.
Fishery Collapse & Global Food Crisis
A strong El Niño caused Peruvian anchovy catches to plummet from 12 million tons to 2 million tons, sending global fishmeal prices soaring and cascading into higher livestock feed costs. Combined with poor Soviet harvests, the event triggered a global food panic and directly spurred the institutionalization of international ENSO research.
“El Niño of the Century” — Unpredicted
The strongest El Niño of the 20th century, yet it was almost completely unpredicted by any agency (partly due to the lack of real-time ocean observations at the time). Global economic losses reached approximately $8.1 billion. The event prompted deep reflection in the international climate community, leading to the TOGA (Tropical Ocean-Global Atmosphere) research program and the TAO buoy array, which fundamentally transformed ENSO science.
Strongest Recorded Event — Successfully Predicted
The strongest El Niño event in the instrumental record, with the Niño 3.4 SST anomaly peaking at +2.4°C. Thanks to the TAO buoy array, NOAA issued an accurate warning approximately 6 months in advance. Global economic losses totaled ~$96 billion, with approximately 23,000 deaths. China’s catastrophic 1998 Yangtze River basin flood was directly linked to the decay phase of this event.
Rivaling 1997–98 as the Strongest
The Niño 3.4 SST anomaly peaked at +2.3°C, comparable to the 1997–98 event. Global losses of approximately $60 billion. Triggered 2.6 million hectares of wildfire in Indonesia, a food crisis affecting tens of millions in southern Africa, and massive global coral bleaching (the Great Barrier Reef lost about 30% of its coral). The year 2016 became the hottest on record at the time.
Weak El Niño
A weak-to-moderate event with a peak Niño 3.4 anomaly of approximately +0.9°C. Global impacts were relatively limited, though Australia experienced severe drought, which laid the dry conditions for the subsequent 2019–20 “Black Summer” bushfire season.
Most Recent Event
A strong El Niño with a peak Niño 3.4 anomaly of +2.0°C. It drove successive global temperature records in 2023 and 2024 (compounded by the long-term global warming trend). Significant climate anomalies were observed across South America, the Horn of Africa, and parts of Southeast Asia. In 2024, the global mean temperature exceeded the pre-industrial baseline by +1.5°C for the first time.
Event Intensity Comparison
The Oceanic Niño Index (ONI) uses the 3-month running mean SST anomaly in the Niño 3.4 region to measure event intensity:
| Event | Peak ONI (°C) | Duration | Category | Greatest Global Impact |
|---|---|---|---|---|
| 1877–78 | ~+2.5 (reconstructed) | ~12 months | Very Strong | India/China famines (contested) |
| 1982–83 | +2.1 | ~18 months | Very Strong | $8.1 billion losses |
| 1997–98 | +2.4 | ~18 months | Very Strong | $96 billion losses |
| 2009–10 | +1.6 | ~12 months | Strong | North America blizzards, Australia heatwave |
| 2015–16 | +2.3 | ~19 months | Very Strong | $60 billion losses |
| 2018–19 | +0.9 | ~8 months | Weak | Australian drought |
| 2023–24 | +2.0 | ~12 months | Very Strong | Global temperature records |
* 1877–78 data reconstructed from proxy records (tree rings, corals, historical documents). ONI classification: Weak (0.5–0.9), Moderate (1.0–1.4), Strong (1.5–1.9), Very Strong (≥2.0).