- 1IPSL - LOCEAN, Paris, France
- 2School of Earth Atmosphere and Environment, Monash University, Clayton, Australia
- 3LLNL - PCMDI, Livermore, USA
- 4NOAA - GFDL, Princeton, USA
- 5NCAS-Climate, University of Reading, Reading, UK
- 6ARC Centre of Excellence for Climate Extremes, Monash University, Clayton, Australia
- 7NOAA - PMEL, Seattle, USA
Earth’s climate naturally fluctuates on timescales ranging from intraseasonal to centennial, even in the absence of changes in external forcings such as greenhouse gases or volcanic eruptions. The El Niño–Southern Oscillation (ENSO) exemplifies this internal (or unforced) variability within the climate system. Climate model simulations also exhibit this internal variability, as demonstrated by the diverse climate conditions observed in "initial-condition large ensembles" (LEs). These LEs enable to isolate the influence of internal variability and detect trends associated with climate change.
By examining the evolution of ENSO in LEs from the 6th Coupled Model Intercomparison Project (CMIP6), we find that ENSO variability has significantly increased during the historical period and is projected to continue increasing under future global warming in most models. This enhanced variability is often linked to changes in equatorial Pacific zonal or vertical temperature gradients. However, our analysis reveals complex, nonlinear relationships between ENSO characteristics and shifts in the mean climate state.
How to cite: Planton, Y., Lee, J., Wittenberg, A., Gleckler, P., Guilyardi, É., McGregor, S., and McPhaden, M.: ENSO Variability Changes in a Warming World, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19093, https://doi.org/10.5194/egusphere-egu25-19093, 2025.
