Sea level height anomalies in the central and eastern Pacific Ocean observed on 4 December 2023 and 1 July 2024.
In 2024, El Niño ended after affecting the global climate with extreme weather conditions for a year.
A natural climate phenomenon has significantly altered sea levels and temperatures, leading to record global temperatures and widespread environmental impacts.
After warming the eastern Pacific Ocean for about a year, El Niño finally died out in May 2024. The natural climate phenomenon has contributed to many months of record high ocean temperatures, extreme rainfall in Africa, low ice cover on the Great Lakes, and severe drought in the Amazon and Central America. As of July 2024, the eastern Pacific was in a neutral phase, but the reprieve may be short-lived.
Understanding the El Niño Southern Oscillation (ENSO)
In the tropical latitudes of the eastern Pacific, the ocean surface cools and warms cyclically in response to the strength of the trade winds—a phenomenon known as the El Niño Southern Oscillation (ENSO). A changing ocean, in turn, disrupts atmospheric circulation in ways that increase precipitation in some areas and bring drought in others.
In May 2023, the easterly trade winds weakened and warm water from the western Pacific moved toward the west coast of the Americas, signaling the onset of El Niño after three consecutive years of La Niña conditions. El Niño continued to strengthen until December 2023 and then faded by mid-May 2024.
Observing and measuring scientists
“It was a big El Niño, but not the biggest we’ve seen in 30 years,” said Josh Willis, an oceanographer at the company NASAJet Propulsion Laboratory (JPL). Willis tracks the signature of sea level change around the world using satellite measurements of sea level. Warmer water expands and raises sea levels, while cooler water contracts and lowers them.
The maps above show sea level height anomalies in the central and eastern Pacific Ocean as observed on July 1, 2024 (right), during the neutral phase, compared to December 4, 2023 (left), near the peak of El Niño. Shades of red indicate areas where the ocean was higher than normal; blue indicates sea levels that were lower than average; and normal sea level conditions appear white. In a report from NOAA‘s Climate Prediction Center, December sea surface temperatures for the key tropical Pacific viewing area (170° to 120° W) measured 2° Celsius above the 1991–2020 average.
Sea level height anomalies in the central and eastern Pacific Ocean observed on December 4, 2023.
Data for the maps were taken by Michael Freilich’s Sentinel-6 satellite and processed by Willis and colleagues at JPL. Note that signals related to seasonal cycles and long-term trends have been removed to highlight sea level anomalies associated with El Niño and other short-term natural phenomena.
Comparison with previous El Niño events
Even at its peak in November and December, the intensity of El Niño in 2023 did not match the largest events of recent decades. During the previous record events in 1997–1998 and 2015–2016, sea levels were much higher (warmer) and the high sea levels extended over a much larger area of ​​the central and eastern Pacific.
Even so, this mildly intense El Niño has contributed to climate disturbances around the world. Rainfall patterns were disrupted in Africa: southern parts of the country suffered a dry spell that dried up almost half of the maize grown in Zambia, while the Horn of Africa experienced devastating floods. A major drought in the Amazon has led to massive bushfires in the northern state of Roraima. El Niño also contributed to heat stress in coral reefs, heavy rainfall on the US West Coast, low ice on the Great Lakes, and fires in Indonesia.
Record of temperature and global temperature anomalies
El Niño often coincides with the warmest years in the global temperature record. Warm sea surface temperatures, in addition to a long-term warming trend caused by greenhouse gases, helped global temperatures jump enough to set a new temperature record in 2023. An analysis by scientists at NASA’s Goddard Institute for Space Studies (GISS) found that May From 2023 to May 2024 was a full year of record high monthly temperatures – an unprecedented streak. Prior to 12 consecutive months of record temperatures, the second-longest streak lasted seven months during the 2015-2016 El Niño.
In May 2024, the easterly trade winds picked up again, returning sea surface temperatures (and sea surface heights) to normal in the eastern Pacific. NOAA’s Climate Prediction Center estimates that these neutral conditions will last through August. They predict that La Niña has a 70% chance of emerging sometime between August and October and will last until winter in the Northern Hemisphere.
NASA Earth Observatory Lauren Dauphin image using modified Copernicus Sentinel (2023) processed data European Space Agency and further edited by Josh Willis, Severin Fournier, and Kevin Marlis/NASA/JPL-Caltech. Story by