Is climate change making El Niño stronger, and what is still debated?

The honest answer is in two parts: climate change adds heat to every El Niño year, but whether it is changing the El Niño cycle itself is still debated. Two separate questions are tangled together. The first is whether El Niño and La Niña themselves are changing. The second is what happens when a natural cycle sits on top of a warming planet. On the second, the evidence is clear: for 2023 the WMO Secretary-General, Celeste Saulo, said that El Niño had contributed to the record temperatures but that greenhouse gases from human activity were "unequivocally the main culprit". And on 22 August 2026 Copernicus recorded the highest average sea surface temperature on record, which it attributed to heat added by El Niño on top of decades of human-driven warming.

On the first question, the experts do not speak with one voice. In climate science, ENSO is known as one of the internal climate variability phenomena, a natural swing. The IPCC's Sixth Assessment Report (2021) found, with medium confidence, that ENSO's amplitude and the frequency of high-magnitude events since 1950 have been higher than over the period from 1850. Some studies since about 2019 have found that climate change is increasing the frequency of extreme El Niño events. Yet in June 2026 the WMO wrote that there is no evidence that climate change increases the frequency or intensity of El Niño events, while noting that it can amplify their impacts because a warmer ocean and atmosphere provide more energy and moisture for extreme weather.

Future trends in ENSO due to climate change remain uncertain, so treat it as an active research question, not settled either way.