"WMO Warns of Very Strong El Niño Persisting Through Early 2027"
El Niño
warm phase of ENSO; SST anomaly >+0.5°C in Niño 3.4 region for five overlapping three-month periods
Walker Circulation
zonal atmospheric loop in tropical Pacific; disrupted by El Niño, suppressing Indian monsoon convection
The El Niño–Southern Oscillation (ENSO) is a naturally recurring ocean-atmosphere coupled phenomenon centred in the tropical Pacific Ocean, operating in two phases: El Niño (warm phase) and La Niña (cool phase). El Niño is formally defined when sea surface temperatures (SSTs) in the Niño 3.4 region of the central-eastern equatorial Pacific exceed the climatological mean by +0.5°C for five consecutive overlapping three-month periods. The accompanying atmospheric signal — the Southern Oscillation — is measured by the Southern Oscillation Index (SOI), tracking pressure shifts between the eastern and western Pacific. Together, ENSO is one of the most powerful drivers of year-to-year climate variability on Earth.
India's Southwest Monsoon (June–September) delivers approximately 75% of annual rainfall against a Long Period Average of roughly 887 mm. Historically, around 60% of strong El Niño years have coincided with below-normal monsoon rainfall in India, though the relationship is not deterministic — modulating factors such as the Indian Ocean Dipole (IOD) and the Madden-Julian Oscillation (MJO) can offset or amplify El Niño's suppressive effect. More broadly, South Asia is identified by the IPCC as a global hotspot for intensifying extreme weather, combining high population density, rain-fed agriculture dependence, fragile mountain ecosystems, and limited adaptive capacity.
The global governance architecture for these risks rests on several pillars: the Sendai Framework for Disaster Risk Reduction 2015–2030, the Paris Agreement under the UNFCCC, and the principle of Common But Differentiated Responsibilities (CBDR). Loss and damage financing — a key demand of vulnerable nations — was formally institutionalised at COP27 in 2022, though the gap between pledged support and actual delivery remains wide.
El Niño suppresses India's monsoon primarily through disruption of the Walker Circulation, the zonal atmospheric loop in the tropical Pacific. Under normal conditions, strong easterly trade winds push warm surface water westward, sustaining rising moist air over the Indo-Pacific Warm Pool and driving monsoon convection over India. During El Niño, trade winds weaken or reverse, warm water shifts eastward, and the rising limb of the Walker Circulation relocates away from the Indo-Pacific region. This suppresses convection, reduces moisture supply to the subcontinent, and typically results in fewer and weaker Low-Pressure Systems (LPS) over the Bay of Bengal — the primary rain-bearing systems for the Indian interior.
Beyond monsoon disruption, ENSO interacts with a broader spectrum of climate shock events across South Asia. …
Consider the following statements:
1.In the tropical zone, the western sections of the oceans are warmer than the eastern sections owing to the influence of trade winds.
2.In the temperate zone, westerlies make the eastern sections of oceans warmer than the western sections.
Which of the statements given above is/are correct?
Consider the following description:
1.Annual and daily range of temperatures is low.
2.Precipitation occurs throughout the year.
3.Precipitation varies between 50 cm - 250 cm.
What is this type of climate?
With reference to the Walker Circulation and its disruption during El Niño, consider the following:
1.Under normal conditions, easterly trade winds push warm surface water westward across the equatorial Pacific.
2.During El Niño, the rising limb of the Walker Circulation shifts toward the Indo-Pacific Warm Pool, enhancing Indian monsoon rainfall.
3.El Niño weakens or reverses trade winds, causing warm water to shift toward the central-eastern Pacific.
Which of the statements given above is/are correct?
Consider the following statements regarding El Niño:
1.El Niño is defined when sea surface temperatures in the Niño 3.4 region exceed the climatological mean by +0.5°C for five consecutive overlapping three-month periods.
2.A 'very strong' El Niño is classified when the Niño 3.4 index exceeds +2.0°C above normal.
3.El Niño's suppressive effect on India's Southwest Monsoon operates with a 1–2 month lag.
How many of the above statements are correct?
With reference to El Niño's impact on India, which of the following statements is/are correct?
1.El Niño tends to suppress kharif crop yields by reducing Bay of Bengal Low-Pressure System formation during the monsoon season.
2.El Niño elevates winter temperatures, which can adversely affect rabi crops such as wheat that require cool conditions for grain development.
3.A positive Indian Ocean Dipole always fully neutralises El Niño's suppressive effect on the Indian monsoon.
Select the correct answer using the code given below:
Consider the following statements regarding the Indian Ocean Dipole (IOD):
1.In its positive phase, the western Indian Ocean warms relative to the eastern Indian Ocean.
2.A positive IOD can partially offset El Niño's suppressive effect on India's Southwest Monsoon.
3.The IOD is also known as the Indian Ocean counterpart of the Walker Circulation.
Which of the statements given above is/are correct?
Match the following ocean-atmosphere phenomena with their primary geographic region:
List I (Phenomenon) — List II (Primary Region)
A.El Niño — 1. Central-eastern equatorial Pacific
B.Indian Ocean Dipole — 2. Indian Ocean (east-west gradient)
C.Walker Circulation — 3. Tropical Pacific (zonal atmospheric loop)
D.Madden-Julian Oscillation — 4. Tropical Indian and Pacific Oceans (eastward-propagating)
Select the correct answer using the code given below:
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