Active El Niño−Southern Oscillation−like interannual variability 120 million years ago

The El Niño−Southern Oscillation (ENSO) is the dominant mode of interannual climate fluctuation, generating teleconnections impacting global climate variability today. Its behavior in past greenhouse climates provides a useful perspective for understanding future ENSO under global warming. Despite annually resolved geologic evidence of active ENSO since the Late Cretaceous, ENSO operation at earlier greenhouse periods is poorly resolved. Here, we present evidence from annually resolved lacustrine sediments in northeast China showing signals of interannual precipitation variability 120 m.y. ago, with major frequency bands of 2−5 yr. A coupled climate simulation of the Early Cretaceous generates ENSO-like variability with similar 2−5 yr periodicities in tropical Pacific sea-surface temperatures and atmospheric teleconnection to northeast China precipitation. The Early Cretaceous ENSO-like variability shows higher frequency and stronger amplitude compared to modern ENSO, resembling predictions of future ENSO evolution.