The Sunita Narain Show: El Niño, climate change and India’s monsoon

The Southwest Monsoon 2026 arrived in Kerala on 4 June 2026, three days later than normal (normal onset date: 1 June), and nine days after IMD's originally f...

What Happened

The Southwest Monsoon 2026 arrived in Kerala on 4 June 2026, three days later than normal (normal onset date: 1 June), and nine days after IMD's originally forecast date.
The India Meteorological Department (IMD) lowered its 2026 Southwest Monsoon forecast to 90% of the Long Period Average (LPA) — classified as "below normal" — down from an earlier projection of 92% of LPA.
IMD assesses a 35% probability of a deficient season (rainfall below 90% of LPA), more than double the climatological baseline probability of 16%, driven by the anticipated development of El Niño conditions during the monsoon season.

Static Topic Bridges

El Niño-Southern Oscillation (ENSO): Mechanism and Phases

ENSO (El Niño-Southern Oscillation) is a recurring climate pattern in the tropical Pacific Ocean involving coupled interactions between ocean surface temperatures and atmospheric circulation. It has two opposing phases — El Niño (warm phase) and La Niña (cool phase) — and a neutral phase. The "Southern Oscillation" refers to the associated fluctuation in atmospheric pressure between the eastern and western Pacific, first documented statistically by Sir Gilbert Walker in the 1920s–1930s.

Normal conditions: Easterly trade winds blow warm surface water westward across the equatorial Pacific toward Asia/Australia; cold deep water upwells along the South American coast.
El Niño: Trade winds weaken or reverse; warm water spreads eastward across the central and eastern Pacific; upwelling suppressed; rainfall shifts eastward, away from Asia and Australia toward the central Pacific.
La Niña: Trade winds intensify; warm water pools further westward; enhanced upwelling off South America; generally associated with above-normal rainfall over India and South/Southeast Asia.
The feedback loop is called the Bjerknes feedback (identified by Jacob Bjerknes, 1969): weakening trade winds → warm water spreads east → further trade wind weakening.
ENSO cycles occur irregularly every 2–7 years; events typically peak around December (El Niño de Navidad — the original name given by South American fishermen as early as the 1600s).
NOAA monitors ENSO using the Oceanic Niño Index (ONI) — the 3-month running mean of sea surface temperature anomalies in the Niño 3.4 region (5°N–5°S, 120°W–170°W).
El Niño is declared when ONI exceeds +0.5°C for five consecutive overlapping 3-month periods.

Connection to this news: A strong El Niño developing during the 2026 Southwest Monsoon season (NOAA estimates 82% probability of El Niño developing during May–July 2026) is the primary driver of IMD's below-normal rainfall forecast.

El Niño–Indian Monsoon Relationship: History and Complexity

The Indian Summer Monsoon Rainfall (ISMR) has a well-documented inverse correlation with El Niño: El Niño years tend to see suppressed convection over the Indian subcontinent, reducing monsoon rainfall. However, this relationship has not been uniform across time — it strengthened between 1901–1940, stabilised between 1941–1980, and has weakened since 1981. This weakening is partly attributed to increased warming of the Indian Ocean (Indian Ocean Dipole) and other modulating factors.

Major drought years historically associated with El Niño: 1877, 1899, 1918, 1972, 1987, 2002, 2009.
The Indian Ocean Dipole (IOD): A positive IOD (warmer western Indian Ocean relative to the eastern) can partially offset the negative impact of El Niño on Indian monsoon.
The ENSO–monsoon teleconnection operates through changes in Walker Circulation and Hadley Circulation — suppressed Walker Circulation during El Niño weakens the monsoon trough.
IMD uses an ensemble of dynamical models and statistical predictors including ENSO indices, IOD, Atlantic SST anomalies, and Eurasian snow cover to produce seasonal forecasts.
The LPA of Indian Summer Monsoon rainfall is 87 cm (for the 1971–2020 base period).
"Below normal" rainfall is defined as 90–95% of LPA; "deficient" is below 90% of LPA.

Connection to this news: The 2026 El Niño is described as "strong," amplifying the already weakened ENSO–monsoon relationship; the compounding effect of background anthropogenic warming is expected to intensify precipitation extremes — alternating intense rain events and prolonged dry spells — even within a below-normal seasonal total.

Climate Change and Monsoon Variability

Anthropogenic climate change adds a separate layer of risk to monsoon behaviour beyond ENSO. A warming atmosphere holds more moisture (Clausius-Clapeyron relation: ~7% more moisture per 1°C warming), which intensifies precipitation when it does occur but also increases the length and severity of dry spells between rain events. For India, this translates into a higher risk of flood events even in below-normal monsoon years — a pattern increasingly observed since the early 2000s.

The global mean surface temperature has risen approximately 1.2°C above pre-industrial levels as of 2024 (IPCC AR6).
India's mean surface temperature has risen 0.7°C over 1901–2018 (IMD data).
The Arabian Sea, which feeds moisture to the Indian monsoon's western branch, has warmed faster than global averages — altering moisture flux patterns.
Increased frequency of "weather extremes" — flash floods, heat waves, prolonged dry spells — is a documented trend even as annual mean rainfall changes remain uncertain.
The Paris Agreement (2015) target of limiting warming to 1.5°C or 2°C is directly relevant to monsoon stability projections.

Connection to this news: The 2026 situation exemplifies the "compound risk" framing — a strong El Niño reducing seasonal totals while climate change increases the probability of concentrated extreme rainfall events within the reduced total, making water management harder, not easier, even in a drought year.

Rainwater Harvesting and Water Security Policy

Rainwater harvesting (RWH) involves the collection and storage of rainwater for later use, reducing dependence on groundwater extraction and surface water diversion. In India, traditional RWH systems (stepwells, johads, tankas, percolation tanks) have a millennia-long history; policy integration into urban and rural water management has accelerated since the 2000s.

The National Water Policy 2012 mandates that rainwater harvesting be made mandatory in new buildings in water-stressed areas.
Model Building Bye-Laws 2016 include mandatory RWH provisions for residential and commercial buildings above specified plot sizes.
Jal Shakti Mission / Jal Jeevan Mission: nodal ministry — Ministry of Jal Shakti; Jal Jeevan Mission targets Har Ghar Jal (tap water to all rural households); Jal Shakti Abhiyan focuses on water conservation at the district level.
NITI Aayog's Composite Water Management Index (CWMI) has flagged that 21 major cities face groundwater depletion by 2030.
India receives about 4,000 billion cubic metres (BCM) of precipitation annually; utilisable water resource is estimated at about 1,123 BCM.

Connection to this news: A below-normal monsoon year, particularly one compounded by El Niño, highlights the structural need for distributed water storage — local RWH, watershed development, and aquifer recharge — as centralised irrigation infrastructure cannot compensate for reduced overall rainfall.

Key Facts & Data

Southwest Monsoon 2026 onset in Kerala: 4 June 2026 (three days late; nine days after IMD's forecast date).
IMD 2026 monsoon forecast: 90% of LPA (Long Period Average of 87 cm for 1971–2020 base period) — "below normal."
IMD probability of deficient season (below 90% LPA): 35%, more than double the climatological probability of 16%.
NOAA estimate: 82% probability of El Niño developing during May–July 2026; 96% probability of El Niño persisting through December 2026–February 2027.
El Niño declared when Oceanic Niño Index (ONI) exceeds +0.5°C for five consecutive overlapping 3-month periods.
ENSO cycle recurs irregularly every 2–7 years.
Major historical drought years linked to El Niño: 1877, 1899, 1918, 1972, 1987, 2002, 2009.
India's total annual precipitation: approximately 4,000 BCM; utilisable water resource: approximately 1,123 BCM.
Global mean temperature rise above pre-industrial: approximately 1.2°C as of 2024 (IPCC AR6).
India's mean surface temperature rise: 0.7°C over 1901–2018 (IMD).