El Niño and Monsoon Deficit in India

India Meteorological Department has forecast ‘below-normal’ monsoon rainfall at 92% of Long Period Average (LPA).

Current Monsoon Deficit in India

LPA Benchmark: LPA for India’s southwest monsoon (June–September) is 87 cm, based on the 1971–2020 average.
El Niño Influence: A developing El Niño, marked by warming of the eastern Pacific Ocean, is likely to suppress monsoon rainfall.
Trend Shift: The forecast signals a likely end to two consecutive years (2024–25) of above-normal rainfall.
Offsetting Factors: A positive Indian Ocean Dipole (IOD) and lower northern hemisphere snow cover may partially offset El Niño’s negative impact.
Drought: IMD classifies rainfall below 90% of LPA as “deficient,” often associated with drought conditions.

Long Period Average is the average rainfall calculated over a long period (30 or 50 years), used as a benchmark to assess monsoon performance.

Agricultural Stress: ~60% farmers dependent on the monsoon face risk to Kharif crop productivity.
Income Shock: Poor rainfall can reduce rural incomes and weaken consumption demand.
Water Scarcity: Deficient rainfall can reduce groundwater recharge and drinking water availability.
Energy Impact: Lower reservoir levels may affect hydropower generation.
Food Inflation: Reduced crop output can push up food prices and inflation.

ENSO Effect: The El Niño phase of ENSO generally weakens the Indian monsoon by disrupting atmospheric circulation.
La Niña: La Niña conditions usually strengthen monsoon rainfall due to enhanced convection over the Indian region.
Indian Ocean Dipole: Positive IOD supports stronger monsoon rainfall; negative IOD suppresses it.
Snow Cover Impact: Lower Eurasian snow cover is associated with a stronger monsoon, whereas higher snow cover weakens it.
Walker Circulation: Changes in east–west atmospheric circulation influence moisture transport and monsoon intensity.
Jet Streams: Position and strength of subtropical jet streams affect the onset, distribution, and withdrawal of the monsoon.
Global Warming: Climate change alters moisture availability and increases variability, causing extreme rainfall events.

El Niño is a climate phenomenon characterised by abnormal warming of surface waters in the eastern and central Pacific Ocean.
Part of ENSO: It is one phase of the El Niño Southern Oscillation (ENSO), a global climate system affecting weather patterns.
Mechanism:
- El Niño occurs when weakened trade winds allow warm Pacific waters to move eastward, disrupting normal ocean circulation.
- This alters pressure systems (e.g., the Walker Circulation), leading to changes in global rainfall and temperature patterns.
Global Impact: It disrupts weather patterns worldwide, causing floods in South America, droughts in Australia and Asia, weaker Indian monsoons, and rising global temperatures.
Impact on India: It is generally associated with a weaker southwest monsoon & reduced rainfall in India.

El Niño–Southern Oscillation: ENSO is a periodic climate phenomenon involving warming (El Niño) and cooling (La Niña) of the central-eastern Pacific Ocean, influencing global weather patterns.
Walker Circulation: It is the atmospheric circulation over the equatorial Pacific, in which air rises over warm waters in the west & sinks over cooler waters in the east, driving trade winds.
Indian Ocean Dipole: IOD is a climate phenomenon where sea surface temperature differences between the western and eastern Indian Ocean influence monsoon rainfall in India.