The El Niño–Southern Oscillation (ENSO) shapes global climate extremes. Although most climate models project its intensification through the 21st century, its behavior beyond 2100 remains unclear. Here, we conducted multi-scenario simulations extending to 2500 with an Earth System Model to assess ENSO responses across different warming levels and analyzed a multi-model ensemble. We find that ENSO amplitude, asymmetry, periodicity, and diversity change non-monotonically: under moderate global warming, ENSO strengthens with persistent positive skewness and ~4-year periodicity. Under extreme global warming, ENSO amplitude and skewness decline, and its period shortens to 2–3 years, favoring Central Pacific events. These non-monotonic changes arise from a shift in the eastern Pacific background from equatorial surface wind divergence to convergence, which promotes ocean heat discharge and efficiently terminates ENSO. Our findings indicate a shift toward more frequent but less intense ENSO variability in a high-warming world, posing challenges for climate projection and adaptation.
Hayashi et al. (Tue,) studied this question.