Precursors

Recent work suggests that decadal changes in equatorial Pacific SST emanate from the tropical South Pacific (Giese et al., 2002). Subsurface temperature in the latter region leads the equatorial SST by about 7 years. Since the southern tropical Pacific temperature shows a distinct cooling since the early 1990’s, one can expect a similar cooling in the equatorial Pacific SST from the late 1990s onward. A similar situation existed in the early 1940’s when the equatorial Pacific experienced a transition to the generally cold regime of  1942–1976 (Zhang et al., 1997).