More frequent central Pacific El Nino and stronger eastern pacific El Nino in a warmer climate

Abstract

El Nino events exhibit rich diversity in their spatial patterns, which can lead to distinct global impacts. Therefore, how El Nino pattern diversity will change in a warmer climate is one of the most critical issues for future climate projections. Based on the sixth Coupled Model Intercomparison Project simulations, we report an inter-model consensus on future El Nino diversity changes. Central Pacific (CP) El Nino events are projected to occur more frequently compared to eastern Pacific (EP) El Nino events. Concurrently, EP El Nino events are projected to increase in amplitude, leading to higher chances of extreme EP El Nino occurrences. We suggest that enhanced upper-ocean stability due to greenhouse warming can lead to a stronger surface-layer response for increasing positive feedbacks, more favorable excitation of CP El Nino. Whereas, enhanced nonlinear atmospheric responses to EP sea surface temperatures can lead to a higher probability of extreme EP El Nino.