El Niño-Southern Oscillation (ENSO)

ENSO is a climate phenomenon involving periodic changes in sea surface temperature in the tropical Pacific Ocean coupled with atmospheric pressure changes (the Southern Oscillation). There are three phases: warm (El Niño), cool (La Niña), and neutral. ENSO occurs in irregular cycles of 2-7 years. ENSO is an important driver of climate variability, including temperature and precipitation, regionally and globally.