Unfolding the relation between global temperature and ENSO

Abstract

An analysis of global temperature and ENSO data indicates that their relationship is more complicated than currently thought. Indeed, it appears that there are two complimenting aspects to this relation. The first (and known) aspect expresses the fact that global temperature increases after an El Nino event and a La Nina event follows an El Nino event. Thus, El Nino forces global temperature. While this is an important result, it is not the entire picture. If it were, ENSO would be independent of global temperature. The second aspect, which is proposed here, suggests a deeper connection between global temperature and ENSO. We find that ENSO is not independent and that positive (negative) global temperature tendency tends to trigger an El Nino (La Nina). Thus, in a warming climate El Nino events will be more frequent than La Nina events. The methodology presented in this paper may elucidate how realistically coupled ocean-atmosphere models simulate the response of climate to global change. Copyright 2005 by the American Geophysical Union.