Which statement best describes ENSO?

• A. A long-term cooling trend in the Southern Ocean.
• B. Recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean.
• C. A periodic cycling of Atlantic hurricane activity.
• D. A seasonal monsoon variation in Asia.

Answer: (B)

ENSO describes a recurring interaction between the ocean and atmosphere in the tropical Pacific. It centers on fluctuations in sea surface temperature in the central and eastern parts of the tropical Pacific, which drive shifts in winds and rainfall that ripple around the globe. When those Pacific waters warm, the phase is El Niño; when they cool, it’s La Niña. This coupled ocean-atmosphere pattern isn’t a long-term trend or a regional monsoon cycle, but a repeating interannual variability that alters weather patterns worldwide.