Fig. 2: Earlier time of emergence (ToE) of eastern-Pacific El Niño-Southern Oscillation (EP-ENSO) than central-Pacific (CP) ENSO.

a Dependence of ToE upon length of time window over which signal and noise are diagnosed for E-index (red) and C-index (blue). b As in a, but for proportion (in percentage) of models that show emergence of E-index (red) and C-index (blue) before 2100. Solid lines and shadings indicate multi-model mean and one standard deviation of a total of 10,000 inter-realisations, respectively, based on a Bootstrap method (see Methods). c ToE diagnosed from a 60–80-year sliding window for E-index variability in all 31 CMIP5 and 37 CMIP6 models. Only models that show ToE spanning the whole 60–80-year window are indicated by red bars, otherwise they are greyed out. Multi-model mean and median values are indicated by the horizontal solid and dashed lines, respectively. Numbers on the upper left denote the number of models showing ToE in the CMIP5 (black) or CMIP6 (purple) multi-model ensemble. d As in c, but for C-index. Results shown here are based on the RCP85/SSP585 scenario for a future warming climate.