Syllabus: GS I & V – Climatology

Why in the News?

Global agencies such as the NOAA Climate Prediction Center and the World Meteorological Organization have forecast a high probability of El Niño in 2026, raising concerns of below-normal monsoon rainfall and higher temperatures in Northeast India.

What is El Niño?

El Niño is a climate phenomenon involving abnormal warming of sea surface temperatures in the central and eastern Pacific Ocean.

Key Features

• Occurs every 2–7 years.
• Lasts about 9–12 months (sometimes longer).
• Leads to changes in wind, pressure, and rainfall patterns globally.
• Associated with low atmospheric pressure over the eastern Pacific.
• It usually produces effects opposite to La Niña.

Origin of the Term

• First identified by Peruvian fishermen.
• Named “El Niño” (Spanish for “little boy”) because it appears around Christmas.

La Niña (Cool Phase)

La Niña is the opposite phase of El Niño, involving cooling of surface waters in the eastern Pacific Ocean.

Key Characteristics

• Can last 1–3 years, often longer than El Niño.
• Associated with high atmospheric pressure over the eastern Pacific.

ENSO System and Monsoon Link

Both La Nina and El Niño are part of the El Niño–Southern Oscillation (ENSO).

The ENSO cycle explains the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific.

ENSO basically involves periodic changes in:

• Sea surface temperatures in the equatorial Pacific Ocean
• Air pressure patterns (Southern Oscillation)

It has three phases:

• El Niño (warm phase)
• La Niña (cool phase)
• Neutral phase

Impact of El Niño on Indian Monsoon

• Often leads to weaker southwest monsoon rainfall.
• Causes higher-than-normal temperatures.
• Increases chances of monsoon breaks (dry spells during rainy season).

Data Insight:

Out of 18 drought years in India in the last 100 years, 13 were linked to El Niño.

Why Northeast India is Vulnerable

• The Northeast has already experienced five consecutive years of below-normal rainfall.
• In 2024–25, the region recorded one of the lowest monsoon rainfalls in 125 years.
• Further rainfall reduction may impact:
• Agriculture and tea production
• Water resources
• Livelihoods in rural areas

Other Influencing Factors

While El Niño is important, monsoon variability depends on multiple factors:

• Indian Ocean Dipole
• Eurasian snow cover
• Regional atmospheric circulation patterns

Thus, El Niño does not always lead to drought, but increases the probability.

Economic and Environmental Implications

• Reduced rainfall can affect crop yields and food security.
• May increase inflation due to rise in food and energy prices.
• Could impact hydropower generation and water supply.
• Linked with heatwaves and extreme weather events.

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