What a ‘Super’ El Niño Might Mean for India’s Monsoon
Context
The National Oceanic and Atmospheric Administration (NOAA) has confirmed the development of an El Niño event and estimates a 63% probability that it could intensify into a Very Strong (Super) El Niño by the Northern Hemisphere winter.
India’s rainfall during 1–16 June has been about 35% below the Long Period Average (LPA), raising concerns about the impact on the southwest monsoon.
What is El Niño?
El Niño is a periodic warming of sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean. It is part of the El Niño–Southern Oscillation (ENSO) phenomenon and generally weakens the South Asian monsoon.
Classification of El Niño (IMD)
| Category | SST Anomaly |
|---|---|
| Weak El Niño | 0.5°C – 1.0°C |
| Moderate El Niño | 1.0°C – 1.5°C |
| Strong El Niño | 1.5°C – 2.0°C |
| Very Strong (Super) El Niño | More than 2.0°C |
Some forecasts indicate that the current event may approach 2.5°C, nearing historical record levels.
Mechanism Behind El Niño
Normal Conditions
- Trade winds blow from east to west across the Pacific Ocean.
- These winds push warm surface waters towards Asia.
- Cooler waters rise along the South American coast through upwelling.
During El Niño
- Trade winds weaken significantly.
- Warm water shifts eastward and accumulates in the central and eastern Pacific.
- This warming further weakens the trade winds, creating a positive feedback loop.
- The altered ocean-atmosphere circulation disrupts global weather patterns, including the Indian monsoon.
Role of Climate Change
- Rising global temperatures have increased ocean heat content.
- Greater background warming may provide additional energy for stronger El Niño events.
Historical Super El Niño Events
Very Strong (Super) El Niño events are rare. Major events include:
- 1972–73
- 1982–83
- 1997–98
- 2015–16
These events produced significant climatic disruptions across the world.
Seasonality of El Niño
El Niño typically:
- Develops during spring.
- Strengthens through the year.
- Peaks during winter.
- Weakens during the following spring.
In some cases, it may persist into a second year.
Impact on India’s Monsoon
Why June Rainfall Is Not the Whole Story
- El Niño’s influence strengthens gradually.
- Its impact is generally felt more strongly during the middle and latter half of the June–September monsoon season.
- Therefore, weak rainfall in June alone does not necessarily determine the final monsoon outcome.
Historical Relationship
Since 1950:
- India has experienced around 24 El Niño years.
- About 15 years recorded below-normal rainfall.
- Around 10 years witnessed deficient rainfall (less than 90% of LPA).
Major Drought Years Linked to El Niño
- 1972
- 1982
- 2009
- 2015
Significance for India
A weak monsoon can affect:
- Agricultural production
- Food security
- Rural incomes
- Inflation
- Water availability
- Fiscal and economic planning
Role of the Indian Ocean Dipole (IOD)
What is IOD?
The Indian Ocean Dipole (IOD) measures the difference in sea surface temperatures between:
- Western Indian Ocean
- Eastern Indian Ocean
Positive IOD
A Positive IOD can enhance monsoon rainfall and partly offset El Niño’s drying effect.
Example: 1997–98
Despite one of the strongest El Niño events on record, India received 2% above-normal rainfall because a strong positive IOD compensated for the adverse effects.
Current Outlook
The India Meteorological Department (IMD) has indicated that the IOD is unlikely to be strong enough this year to fully neutralize the impact of El Niño.
Global Impacts of Strong El Niño
1982–83 Event
- Severe droughts in Australia
- Extensive bushfires
- Dry conditions across Indonesia
1997–98 Event
- Massive forest fires in Southeast Asia
- Severe haze episodes
- Death of nearly one-sixth of the world’s coral reefs
- Record global temperatures
2015–16 Event
- Mass bleaching of the Great Barrier Reef
- Severe droughts and food shortages in parts of Africa
Impact on Tropical Cyclones
El Niño alters the distribution of cyclone activity across ocean basins.
Atlantic Ocean
- Increased vertical wind shear suppresses hurricane formation.
- Fewer Atlantic hurricanes are generally observed.
Central and Eastern Pacific
- Conditions become more favorable for hurricane development.
Western Pacific
- Greater likelihood of storms intensifying into Super Typhoons.
- These storms typically recurve toward East Asia or the Americas rather than directly affecting India.
