UPSC Notes

El Niño-Southern Oscillation (ENSO)

PYQs

17

Articles

3

Momentum

45

Phase IFoundation

Background

Overview

Understanding El Niño is crucial for predicting its impact on India's agricultural productivity, food security, water resource management, and overall economic stability. It is a key factor in climate change studies, disaster preparedness, and formulating agricultural policies.

The El Niño-Southern Oscillation (ENSO) is a recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean, significantly influencing global weather patterns, including the Indian monsoon.

Phase IIStatic core

Facts & tables

Key facts

Phases

El Niño (unusual warming of Pacific waters), La Niña (unusual cooling of Pacific waters), and Neutral.

Impact on India

El Niño is typically associated with weaker monsoon rainfall and droughts in India; La Niña often brings stronger monsoons.

Mechanism

Involves complex interactions between ocean surface temperatures and atmospheric pressure (Southern Oscillation).

El Niño phase

Characterized by warmer-than-average sea surface temperatures in the equatorial Pacific.

Global impact

Alters atmospheric circulation, leading to varied weather patterns worldwide (e.g., increased temperatures, droughts in some regions, heavy rainfall in others).

Indian context

Often associated with weaker Indian monsoons and drought conditions.

Intensity

The current El Niño is expected to be among the most intense on record.

Characteristics

Characterized by warmer-than-average sea surface temperatures in the equatorial Pacific, leading to shifts in atmospheric pressure and wind patterns.

Reference table

Static syllabus anchors

TypeReference
Conceptual areaPhysical & Regional Geography
Conceptual areaClimate Change & Conventions
Conceptual areaIndian Hydrography & Water Bodies
Conceptual areaClimate Phenomena
Conceptual areaIndian Geography

Reference table

Institutions & roles

BodyRole
National Weather ServiceTracks and forecasts enso events
United NationsMonitors and warns about global climate impacts
India Meteorological Department (IMD)Forecasts and monitors
Food and Agriculture Organization (FAO)Monitors global food prices and security
Phase IIIExam lens

Prelims angle

Overview

Prelims angle: Multi-statement analysis

Prelims angle: Conceptual understanding

Quick revision

  • Pacific Ocean warming (El Niño) or cooling (La Niña).
  • El Niño often linked to Indian monsoon droughts.
  • La Niña generally strengthens Indian monsoon.
  • Key factor in global climate variability.
  • ENSO: periodic warming/cooling of equatorial Pacific.

High-confidence PYQs

Topic timeline

Physical & Regional GeographyClimate Change & ConventionsIndian Hydrography & Water BodiesClimate Phenomena

Is India getting hotter?

31 May 2026 · ENSO is a major Pacific Ocean climate pattern with El Niño (warming) and La Niña (cooling) phases, profoundly impacting global weather, especially weakening the Indian monsoon during El Niño events.

Read article

Heat wave bringing record-breaking temps, heightened wildfire risk to parts of western U.S.

02 Aug 2026 · ENSO, particularly El Niño, is a major oceanic-atmospheric phenomenon in the Pacific that drives global weather anomalies, influencing temperatures, rainfall, and extreme events, with significant implications for India's monsoon.

Read article

Despite recent monsoon revival, why El Niño fears are not over yet

10 Aug 2026 · El Niño is a Pacific Ocean warming phenomenon that typically weakens the Indian monsoon, impacting agricultural output, food prices, and requiring government intervention for food security.

Read article

Related topics

Practice writing on this topic

UPSC has asked 17 linked questions on El Niño-Southern Oscillation (ENSO) in Mains. Write an answer to one — and get it evaluated.

UPSC Prelims PYQs on El Niño-Southern Oscillation (ENSO)

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