November 25, 2019 | Published by | ,

Picture: Clouds from the beach. Credit: Clem Onojeghuo (Unsplash).

Since 1979, three extreme El Niño events occurred, in 1982/83, 1997/98, and 2015/16, with pronounced impacts that disrupted global weather patterns, agriculture, fisheries, and ecosystems. Although all three episodes are referred to as strong equatorial eastern Pacific (EP) El Niño events, the 2015/16 event is considered as a mixed regime of both EP and central Pacific (CP) El Niño.

Extreme El Niño events have been projected to occur more frequently under greenhouse warming. The projections considered two characteristics of extreme El Niño: convective and warm extremes, based respectively on the amount of rainfall and surface temperature pattern. The association between the two was not examined.

This study found in CMIP5 models that are able to simulate both types of events, that convective extremes do not always coincide with warm extremes. The disassociation becomes more distinct under greenhouse warming with higher occurrences of convective extremes than warm extremes.

This is attributed to the migration of western Pacific convection and convergence zones toward eastern equatorial Pacific associated with faster warming over the region under greenhouse warming.