Q1. Consider the following statements regarding El Niño and its climatic influence:

1. A single El Niño event can produce contrasting climatic outcomes in different parts of the world.
2. The climatic influence of El Niño is primarily transmitted through changes in atmospheric circulation rather than through the physical movement of warm Pacific Ocean water to every affected region.
3. The recurrence of El Niño at irregular intervals means that every El Niño event must have the same duration and intensity.
4. El Niño can simultaneously increase the likelihood of drought in one region and excessive rainfall or flooding in another.

How many of the statements given above are correct?

(a) Only one
(b) Only two
(c) Only three
(d) All four

Answer: (c)

Explanation:

• Statement 1 — Correct: El Niño modifies global atmospheric circulation, producing regionally different rainfall and temperature anomalies.
• Statement 2 — Correct: Its global teleconnections operate substantially through altered atmospheric circulation and associated ocean–atmosphere interactions.
• Statement 3 — Incorrect: El Niño events vary considerably in duration and intensity; the typical duration does not mean every event follows an identical pattern.
• Statement 4 — Correct: The same El Niño episode can contribute to drought in some regions and enhanced precipitation/flooding in others.

Q2. With reference to the El Niño–Southern Oscillation (ENSO), consider the following statements:

1. El Niño involves anomalous warming of sea-surface temperatures in the central and eastern tropical Pacific Ocean and is generally accompanied by a weakening of the trade winds.
2. La Niña represents the opposite phase of ENSO and is generally associated with stronger-than-normal trade winds.
3. The occurrence of El Niño necessarily results in deficient summer monsoon rainfall over India in the same year.
4. ENSO is exclusively an oceanic phenomenon involving periodic changes in Pacific Ocean temperatures.

Which of the statements given above is/are correct?

(a) 1 and 2 only
(b) 1, 2 and 3 only
(c) 2 and 4 only
(d) 1, 3 and 4 only

Answer: (a)

Explanation:

• Statement 1 — Correct: El Niño is characterised by anomalous warming of the central/eastern tropical Pacific, generally accompanied by weakened trade winds.
• Statement 2 — Correct: La Niña involves anomalous cooling in the same region and generally stronger trade winds.
• Statement 3 — Incorrect: El Niño increases the risk of a weaker Indian monsoon but does not deterministically produce deficient rainfall every time.
• Statement 4 — Incorrect: ENSO is a coupled ocean–atmosphere phenomenon, involving both oceanic temperature anomalies and atmospheric circulation changes.