Nature Climate Change says El Nino frequency could double due to climate change. The result: “severely disrupted global weather patterns, affecting ecosystems^{4, 5}, agriculture⁶, tropical cyclones, drought, bushfires, floods and other extreme weather events worldwide^{3, 7, 8, 9}”

El Niño events are a prominent feature of climate variability with global climatic impacts. The 1997/98 episode, often referred to as ‘the climate event of the twentieth century’^{1, 2}, and the 1982/83 extreme El Niño³, featured a pronounced eastward extension of the west Pacific warm pool and development of atmospheric convection, and hence a huge rainfall increase, in the usually cold and dry equatorial eastern Pacific. Such a massive reorganization of atmospheric convection, which we define as an extreme El Niño, severely disrupted global weather patterns, affecting ecosystems^{4, 5}, agriculture⁶, tropical cyclones, drought, bushfires, floods and other extreme weather events worldwide^{3, 7, 8, 9}. Potential future changes in such extreme El Niño occurrences could have profound socio-economic consequences. Here we present climate modelling evidence for a doubling in the occurrences in the future in response to greenhouse warming. We estimate the change by aggregating results from climate models in the Coupled Model Intercomparison Project phases 3 (CMIP3; ref. 10) and 5 (CMIP5; ref. 11) multi-model databases, and a perturbed physics ensemble¹². The increased frequency arises from a projected surface warming over the eastern equatorial Pacific that occurs faster than in the surrounding ocean waters^{13, 14}, facilitating more occurrences of atmospheric convection in the eastern equatorial region.