What effect is global warming having on El Niño events? Are they becoming more or less frequent? And are they growing more intense?
The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) concludes no clear evidence of long-term trends that can be distinguished from natural variability in most major climate phenomena including El Niño-Southern Oscillation (ENSO). In near term, changes in ENSO and its associated climate impacts are likely to continue to be dominated by natural variability. In the long term, ENSO-related rainfall variability is expected to increase, meaning El Niño and La Niña could have a stronger influence on rainfall extremes in some regions.
How do scientists measure and track the effects of global warming on El Niño?
Scientists track the influence of climate change on ENSO by examining changes in sea surface temperatures, atmospheric circulation and the frequency and intensity of El Niño and La Niña events, both in observed data as well as climate model simulations under different scenarios. While some studies suggest anthropogenic warming may be influencing ENSO variability, leading to more frequent El Niño events in recent decades, ENSO is also strongly shaped by natural internal variability, making attribution difficult. For example, a recent large-ensemble modelling study finds that the observed rise in multi-year La Niña events since the 1960s is mainly driven by internal variability, with external forcing playing only a minor role.
Are current climate models adept at predicting how El Niño events could behave in the future with warming in excess of 1.5ºC or even 2ºC?
Climate models are the main tool for projecting how El Niño events may change under future warming. However, they often show biases in several key features, including circulation patterns and the distribution of sea surface temperatures across the ocean. As a result, models simulate changes in El Niño teleconnections to different extents across regions, highlighting the need for continued improvements in climate models and further research for better future projections..
What aspects of warming’s effects on El Niño events still need research?
Key uncertainties remain around whether El Niño events will become stronger or more frequent, how their spatial patterns may shift, and how their global impacts will change. Addressing these issues require longer and higher-quality observational records, improved climate models with reduced systematic biases, better representation of internal climate variability, and a deeper understanding of complex ocean–atmosphere feedbacks in the tropical Pacific.
This interview was originally published in the June 16-30, 2026 print edition of Down To Earth