A Recent Shift Toward an El Niño-Like Ocean State in the Tropical Pacific and the Resumption of Ocean Warming

Abstract

Since approximately 2011, the tropical Pacific has been sharply shifting toward an opposite phase to that observed in the previous decade. This shift has coincided with a recent resumption of global warming after a hiatus in the 2000s. Based on a model-data analysis using an ensemble empirical mode decomposition, we identified a distinct low-frequency mode of the sea level in the tropical Pacific and showed its connection to global ocean warming and the suppression of global warming during the early 2000s, as well as the resumption of warming during recent years. Hindcast and model experiments conducted to illustrate the physical mechanism linking the decadal mode to the Pacific Decadal Oscillation-related trade winds, which regulate the strength of the Equatorial Undercurrent and the surface temperature of the tropical Pacific Ocean, revealed an El Niño-like state for the last several years.