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Instead of the La Niña events with no significant change in their surface expressions, the recent increasing frequency of central Pacific El Niño events is suggested to be related to global warming. There is yet no consensus on the impacts of the recent global warming on such asymmetric changes of El Niño‐Southern Oscillation (ENSO) events. Here we show the frequency of the extreme cold/moderate warm events both increases in the central equatorial Pacific over the past decades. We attribute the change of ENSO diversity to the positive cold tongue mode under recent global warming, which gives rise to an intensification, contraction, and westward shift of Walker circulation accompanied by an uplift of the thermocline. Our results propose a unified explanation for the changes of ENSO diversity under the recent global warming, which carries important implications for the relationship between global warming and ENSO. Plain Language Summary: El Niño‐Southern Oscillation (ENSO) events, characterized by sea surface temperature anomaly patterns in the tropical Pacific, have great global climate impacts by alternating between warm El Niño and cold La Niña phases. At the expense of the conventional El Niño peaking in the eastern Pacific, the recent increasing frequency of El Niño events with warming sea surface temperature anomalies concentrated in the central equatorial Pacific is suggested to be related to global warming, whereas for the La Niña events, there seems to be no significant change in their surface expressions. There is yet no consensus on the impacts of the recent global warming on such asymmetric changes of ENSO events. Our results show the increasing frequency of both the extreme cold and moderate warm events (ENSO diversity) can be ascribed to the positive cold tongue mode under the recent global warming. The positive cold tongue mode gives rise to an intensification, contraction, and westward shift of Walker circulation accompanied by an uplift of the thermocline, which enlarges the sea surface temperature morphology changes of El Niño but covers up the surface expression of La Niña. Key Points: The frequency of the extreme cold/moderate warm events increases in the central equatorial Pacific under recent global warmingThe positive cold tongue mode induces intensification, contraction, and westward shift of Walker circulation and uplift of the thermoclineThe positive cold tongue mode enlarges the sea surface temperature morphology changes of El Niño but covers up those of La Niña [ABSTRACT FROM AUTHOR]