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Abstract The 2023/24 El Niño commenced with an exceptionally large warm water volume in the equatorial western Pacific, comparable to the extreme 1997/98 and 2015/16 events, but did not develop into a super El Niño. This study highlights the critical role of contrasting Northern Pacific Meridional Mode (NPMM) conditions in this divergence. Warm NPMM conditions during the 1997/98 and 2015/16 events created a positive zonal sea surface temperature (SST) gradient in the equatorial western-central Pacific and enhanced Madden-Julian Oscillation (MJO) propagation, driving sustained westerly wind bursts (WWBs) and downwelling Kelvin waves that intensified both events. In contrast, the cold NPMM during 2023/24 induced a negative SST gradient and suppressed MJO activity, resulting in weaker WWBs and limited eastward wave activity, preventing the event from reaching super El Niño intensity. A 2,200-year CESM1 pre-industrial simulation corroborates these observational findings, underscoring the importance of NPMM interference in improving El Niño intensity predictions. 

Abstract The geographic center of El Niño has shifted from the tropical eastern Pacific (EP) in the 20th century to the tropical central Pacific (CP) in the 21st century. Analyzing data spanning 1948–2018, this study uncovers notable alterations in the impact of the changing El Niño patterns on California market squid (Doryteuthis opalescens) landings. While the traditional EP El Niño in the 20th century significantly reduces squid landings, this impact diminishes with the ascent of the CP type of El Niño in the 21st century. Remarkably, the CP‐I type of El Niño, a specific variant where warming occurs predominantly in the central Pacific and is often less intense but more frequent than traditional El Niño events, can even amplify squid landings. These transformations stem from variations in sea surface temperature, trade winds, and Sverdrup transport associated with different El Niño types. These findings suggest that the fishery community should consider developing adaptive approaches to address the evolving impacts of El Niño. 

Abstract During the past two decades, the Maritime Continent (MC) has experienced increased deforestation. Here we show, with ensemble idealized deforestation experiments, that the MC deforestation could potentially alter the complexity (i.e., event‐to‐event differences) of the El Niño‐Southern Oscillation (ENSO) in terms of its spatial pattern and temporal evolution. The deforestation model run increases the occurrences of the Central Pacific and multi‐year types of ENSO compared to the control experiments. This change in ENSO complexity can be attributed to MC's intensification of the subtropical ENSO dynamics, commonly known as the seasonal footprinting mechanism. The deforestation amplifies the mean state of the subtropical high over the northeastern Pacific, leading to an increased dominance of subtropical ENSO dynamics in determining the ENSO pattern and evolution. This idealized coupled climate modeling study suggests that MC deforestation has a potential to alter ENSO's complexity, making El Niño more complex and less predictable.