The impact of recent super El Niños on sea level rise
El Niños and La Niñas are the third-most dominant influences on Earth's climate, after the sun and the greenhouse effect. But they haven't been easy to decipher or to predict in terms of when they will happen and what exact effects they will have on the global climate.
A new paper compares two recent strong El Niños, their differing effects on globally averaged sea level and the details that distinguished them. The work is published in the Journal of Geophysical Research: Oceans.
El Niños are characterized by warmer-than-usual sea surface temperatures in the Pacific Ocean along the equator, especially in the region called "Niño 3.4." If sea surface temperature anomalies in this region are positive, the state is El Niño; if negative, it is La Niña. Otherwise, the ENSO state (El Niño–Southern Oscillation) is neutral. (Average monthly anomalies for the Niño 3.4 region are published here.)
El Niños elevate global temperatures for their duration; La Niñas lower them. So the impact on global sea level is not surprising. This new research examines how global average sea level responded to the 2014–2016 El Niño and the 2023–2024 El Niño. Both intervals were strong as El Niños go, with sea surface temperature anomalies peaking above 2.0°C. Record global temperatures were seen in 2015 and 2016, and again in 2023 and 2024.
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