Projections of faster onset and slower decay of El Nino in the 21st century

Abstract

Future changes in the seasonal evolution of the El Nino-Southern Oscillation (ENSO) during its onset and decay phases have received little attention by the research community. This work investigates the projected changes in the spatio-temporal evolution of El Nino events in the 21(st) Century (21 C), using a multi-model ensemble of coupled general circulation models subjected to anthropogenic forcing. Here we show that El Nino is projected to (1) grow at a faster rate, (2) persist longer over the eastern and far eastern Pacific, and (3) have stronger and distinct remote impacts via teleconnections. These changes are attributable to significant changes in the tropical Pacific mean state, dominant ENSO feedback processes, and an increase in stochastic westerly wind burst forcing in the western equatorial Pacific, and may lead to more significant and persistent global impacts of El Nino in the future. The El Nino - Southern Oscillation can have global impacts, therefore assessing its future occurrence is needed. Here, the authors project that El Nino will grow at a faster rate, persist longer over the eastern and far eastern Pacific, and have stronger and distinct remote impacts in the 21st Century