El Niño · GS-I
A distant Pacific phenomenon may be drying India’s north, says study ↗
Consider the following statements regarding Pacific Ocean phenomena and their influence on Indian monsoon rainfall:
- El Niño, characterised by warming of the Central Pacific, is associated with reduced southwest monsoon rainfall over India.
- The Pacific Decadal Oscillation (PDO) correlates positively with Indian monsoon rainfall, reinforcing rainfall when in its warm phase.
- When El Niño and the PDO are in phase with each other, their combined effect on the Indian monsoon is stronger than when either operates alone.
Which of the statements given above is/are correct?
Explanation
Statement 1 is correct: El Niño — a warming of the Central Pacific — is well-established as a driver of weakened southwest monsoon rainfall over India; this is a foundational teleconnection in Indian climate science. Statement 2 is incorrect: the Pacific Decadal Oscillation (PDO) correlates *negatively* with Indian monsoon rainfall, much like the El Niño–La Niña cycle. A warm (positive) phase of the PDO tends to suppress Indian monsoon rainfall, not reinforce it. Statement 3 is correct: studies have shown that when El Niño and the PDO are 'in phase' (i.e., both in their warm, monsoon-suppressing phases), their effects on the Indian monsoon reinforce each other, producing a stronger suppression than either would alone; when they are out of phase, their effects partially offset one another.