UPSC Darpan

Environment & EcologyGS39 October 2026

WMO says a strong El Niño will last into 2027, worsening Delhi’s winter air outlook

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The news

Bengaluru, October 8. The World Meteorological Organization (WMO) said El Niño will peak in October-December, extending into spring 2027. Secretary-General Celeste Saulo put the likelihood of it persisting through February 2027 at “near-100 per cent”, calling it “potentially one of the strongest since at least 1950”. Sea temperature in the Niño 3.4 region of the central Pacific was 2.5°C above normal in August, IE reports. El Niño, the warm phase of the El Niño Southern Oscillation, usually weakens Indian rainfall. India’s monsoon ended with a 12.6% deficit, 759.4 mm against a long period average of 868.6 mm, per IMD data as reported, the driest in 11 years. In an IE op-ed, SAFAR’s founder Gufran Beig warns that a “Super El Niño” will weaken winds and suppress western disturbances over north India, trapping pollution just as stubble fires and Diwali crackers peak in early November.

The chain in one line: Central Pacific warms over 0.5°C above normal → monsoon falls 12.6% short → El Niño persists into 2027 → calm, dry north Indian winter → pollution trapped over Delhi as farm fires and crackers peak

Static syllabus linkage

  1. El Niño is the warm phase of ENSO, tracked in the Niño 3.4 region. ENSO is an equatorial Pacific ocean-atmosphere cycle with three phases: warm (El Niño), neutral and cool (La Niña), recurring every two to seven years. An El Niño is declared when sea-surface temperature in the Niño 3.4 region stays at least 0.5°C above normal over several consecutive months. A positive Indian Ocean Dipole can partly offset its effect on Indian rainfall.
  2. IMD grades the monsoon against the long period average. The long period average (LPA) for the June–September season is about 87 cm, based on 1971–2020. Rainfall below 90% of LPA is “deficient”, 90–95% “below normal”, 96–104% “normal”, 105–110% “above normal” and above 110% “excess”.

Why UPSC loves this

  1. GS1 “important geophysical phenomena” meets GS3 “environmental pollution”. ENSO is a perennial Prelims topic; its link to winter air is a cross-paper Mains connection.

Prelims nuggets

  • The Niño 3.4 region in the central equatorial Pacific is the standard index area for declaring El Niño and La Niña.
  • IMD terms seasonal monsoon rainfall below 90% of the long period average “deficient”.
  • The monsoon long period average is about 87 cm, computed over 1971–2020.
  • SAFAR is the air-quality forecasting system of the Ministry of Earth Sciences.

Analysis

  1. Weather can make the same emissions far more dangerous. El Niño adds no smoke, but calm winds and a low inversion layer, the lid of warm air that stops pollutants rising, keep it near the ground, and without western disturbances no rain washes it out. Identical emissions thus produce worse air. Targets that ignore meteorology will be missed and wrongly blamed on enforcement.
  2. Lens — Short-term relief and long-term reform: emergency curbs are not a plan. Emergency bans on construction and vehicles buy days of relief and are politically easy. Beig argues for airshed management, treating the whole Indo-Gangetic region as one unit, and notes that NCAP still rewards cities for cutting PM10, which over-weights dust. The sound judgement is to keep emergency curbs but fund regional, PM2.5-based action that outlasts one El Niño.
  3. The drought’s cost runs into rabi and power. Low soil moisture and reservoirs weaken rabi sowing, and a warm winter can stress wheat at grain filling; heat and weak hydro output already pushed power demand to records. One shock, three bills: food, energy and air.

Possible Mains question

Explain how a strong El Niño can worsen winter air quality in north India. (10 marks, 150 words)

Model approach

  1. Directive — Explain. Set out the mechanism step by step.
  2. Introduction — WMO expects El Niño to last into 2027. Note the 12.6% monsoon deficit.
  3. Body — weaker winds and a lower inversion layer trap pollutants. Draw a box diagram: warm Pacific → calm, dry north India → shallow mixing layer → PM2.5 builds.
  4. Body — absent western disturbances remove the natural rain wash. Value-addition: November 5-10 has historically been Delhi’s worst window, Beig notes.
  5. Conclusion — move to airshed-based, PM2.5-focused management. Cite NARFI under the Principal Scientific Adviser.

Administrator's brainstorm

As Chief Secretary of Delhi, how would you prepare for a winter the forecasters say will be unusually stagnant?

I would trigger graded curbs on forecasts of stagnant days, not wait for the index to cross thresholds. I would ask CAQM to coordinate with Punjab and Haryana on evening fire detection using geostationary data. Hospitals would be told to plan for respiratory surges in early November. Public messaging would explain why this winter is worse, so curbs are not seen as arbitrary.