El Niño and Monsoon: Complex Interactions and Impacts

Why in the News?

The India Meteorological Department (IMD) reported that the 2026 southwest monsoon was 'deficient', ending 13% below the long-term average, despite strong El Niño conditions in the Pacific Ocean.

Key Highlights

• Since 1950, five of seven Indian monsoons coinciding with moderate or strong El Niño events were 'deficient'.

• In 1997, despite a strong El Niño, India received nearly normal monsoon rainfall due to a positive Indian Ocean Dipole (IOD).

• In 2026, equatorial Pacific sea-surface temperatures were 1.98°C above normal, but the monsoon ended 13% below average.

• The IOD was neutral in 2026, failing to offset El Niño's impact on the monsoon.

• IMD forecasts for 2026 predicted 92% of the long-term average rainfall, but actual rainfall was 87.4%.

Know the Basics

• El Niño-Southern Oscillation (ENSO): A climate pattern where weakened Pacific trade winds cause warm water to move east, impacting global weather.

• Indian Ocean Dipole (IOD): A temperature difference between the western and eastern Indian Ocean, influencing monsoon winds and rainfall.

• Madden-Julian Oscillation: A tropical weather phenomenon involving cloud and rain waves that recur every 30-60 days.

Detailed Analysis

El Niño and Monsoon Rainfall Variability

• Strong El Niño events often lead to deficient monsoons, as seen in five out of seven such years since 1950.

• 1997 was an exception, with nearly normal rainfall despite IMD forecasting an 8% deficit.

Role of the Indian Ocean Dipole

• A positive IOD strengthens moisture-laden winds towards India, offsetting El Niño's adverse effects, as in 1997.

• In 2026, the IOD remained neutral, failing to counter El Niño's impact on the monsoon.

Forecasting Improvements and Challenges

• IMD updated its forecasting methods in 2021, combining multiple global climate models for better accuracy.

• Despite improved forecasts, predicting IOD phases remains challenging, as seen in 2026 when models differed on its behaviour.

Significance for India

• The southwest monsoon supplies three-fourths of India's annual rainfall, crucial for agriculture and water resources.

• Weak monsoons reduce farm incomes, raise food prices, and strain drinking-water supplies.

• UPSC could test this topic under Geography or Environment, linking ENSO and IOD to monsoon variability.

• Understanding ENSO and IOD is essential for disaster preparedness and climate resilience planning.

Challenges

• Neutral IOD phases during strong El Niño years limit the monsoon's recovery potential.

• Forecasting IOD behaviour remains inconsistent, affecting monsoon predictions.

• Climate variability due to factors like Antarctic wind patterns complicates monsoon forecasting.

Way Forward

• IMD should refine models for better prediction of IOD phases and ENSO impacts.

• Researchers must study regional factors like the Antarctic wind belt's influence on the IOD.

• Policymakers should integrate climate forecasts into agricultural and water resource planning.

• Global collaboration on climate studies can improve understanding of ENSO and IOD dynamics.