Acronym for El Niño–Southern Oscillation, coined in the early 1980s in recognition of the intimate linkage between El Niño events and the Southern Oscillation, which prior to the late 1960s had been viewed as two unrelated phenomena. The global ocean–atmosphere phenomenon to which this term applies is sometimes referred to as the “ENSO cycle. ” See also El Niño, La Niña, Southern Oscillation.