"El Niño is a necessary but not sufficient condition for monsoon failure in India." Examine this with reference to the Indian Ocean Dipole.

El Niño is the warm phase of the El Niño Southern Oscillation (ENSO). It recurs every 2–7 years. Pacific trade winds weaken, and warm water and rain clouds drift east, away from Indonesia [6]. It is India's strongest single risk factor for monsoon failure. The Indian Ocean Dipole (IOD) often decides whether that risk becomes an actual deficit.

El Niño as the dominant risk factor

• Track record: seven monsoons since 1950 coincided with a moderate or strong El Niño. Five were deficient (≥10% below the 87 cm average), including 2026 [6].
• Mechanism: convection shifts eastward, taking rain-bearing systems away from the Indo-Pacific warm pool [6].
• Forecast weight: as El Niño developed in 2026, IMD's estimated chance of a deficient season rose from 35% in April to 60% in May. In a normal year that chance is 16% [4][5].

Why it is not sufficient: the IOD as modulator

• Positive IOD offsets El Niño: 1997 had one of the 20th century's strongest El Niños. Yet a positive IOD helped June–September rainfall end 2% above normal [2][3].
• 2023: an El Niño year that ended only "below average", not deficient [6].
• Negative IOD amplifies: El Niño combined with a negative IOD makes below-normal rainfall more likely [1].
• Timing matters: in 2026 IMD expected the IOD to stay neutral and turn positive only late in the season [4]. The monsoon closed about 13% short, and East and Northeast India had their driest season since 1901 [6].

El Niño ──► raised deficit risk
   ├─ + positive IOD during season ──► normal rain (1997)
   ├─ + neutral / late-positive IOD ──► deficit (2026)
   └─ + negative IOD ──► higher odds of below-normal rain

Fig: The IOD modulates El Niño's impact

Is it strictly "necessary"?

• The monsoon depends on several ocean basins. IMD tracks ENSO and the IOD as separate drivers [1]. El Niño is therefore better described as the dominant risk than as a strict precondition.
• Judging by El Niño alone in 1997 led to fears of an extreme deficit that never came [2].

Conclusion

El Niño loads the dice, but the IOD's sign and timing often settle the outcome. The statement holds for "not sufficient" and is overstated on "necessary". IMD's coupled Monsoon Mission forecasts already track ENSO and the IOD together [4]. Communicating deficit probabilities and expected IOD timing would let states prepare for drought early. That would protect rain-fed farmers and advance SDG 2 (Zero Hunger) and SDG 13 (Climate Action).