Emergence of the Central Atlantic Nino

The Atlantic Nino is characterized by sea surface warming in the equatorial Atlantic, which can trigger La Nina, the cold phase of El Nino-Southern Oscillation (ENSO). Although observations show that the Atlantic Nino has weakened by approximately 30% since the 1970s, its remote influence on ENSO remains strong. Here, we show that this apparent discrepancy is due to the existence of two types of Atlantic Nino with distinct patterns and climatic impacts, which we refer to as the central and eastern Atlantic Nino. Our results show that with equal strength, the central Atlantic Nino has a stronger influence on tropical climate than its eastern counterpart. Meanwhile, the eastern Atlantic Nino has weakened by approximately 50% in recent decades, allowing the central Atlantic Nino to emerge and dominate the remote impact on ENSO. Given the distinct climatic impacts of the two types, it is necessary to distinguish between them and investigate their behaviors and influences on climate in future studies.