A possible mechanism for El Nino-like warming in response to the future greenhouse warming

Abstract

Using the climate change experiments generated for the Fourth Assessment of the Intergovernmental Panel on Climate Change, a possible mechanism for the El Nino-like warming in response to the greenhouse warming is suggested. From the coupled global climate model (CGCM) simulations with climate change scenario, it is found that the Bjerknes air-sea coupled process is a dominant contributor to the tropical Pacific response. However, it is revealed that most CGCMs commonly simulate the off-equatorial maximum of precipitation change. It is suggested here that the off-equatorial precipitation and the associated equatorial westerlies play a seeding role in triggering an El Nino-like warming response. Atmospheric GCM (AGCM) experiments show that even uniform sea-surface temperature (SST) warming leads to off-equatorial increase in precipitation which brings equatorial westerlies, implying that these non-uniform (off-equatorial) responses can play a seeding role for the El Nino-like warming pattern. Copyright (C) 2010 Royal Meteorological Society