Introduction

El Niño, a recurring climatic phenomenon linked to the abnormal warming of the Pacific Ocean, is globally known for disrupting weather systems. In India, it is generally associated with weakening of the southwest monsoon. However, recent studies highlight a paradox: while El Niño suppresses seasonal rainfall overall, it simultaneously heightens the risk of extreme daily downpours in India’s wetter regions. This dual impact has significant implications for agriculture, water management, and disaster preparedness.

Understanding El Niño and La Niña

• El Niño: Abnormal warming of central and eastern Pacific Ocean waters, altering global atmospheric circulation.

• La Niña: Opposite phenomenon, marked by cooling of Pacific waters, often strengthening monsoon rainfall.

• Impact Mechanism: Warmer Pacific waters alter rising and sinking air currents, suppressing large-scale rainfall but encouraging sporadic, intense convective storms.

Impact on Indian Monsoon

Suppression of Seasonal Rainfall

• Broad weakening of the southwest monsoon during El Niño years.

• Reduced number of rainy days, especially in drier regions such as Rajasthan and parts of central India.

Intensification of Extreme Rainfall

• Despite fewer rainy days, the intensity of rainfall events in wetter regions rises sharply.

• Central monsoon zone (Gangetic West Bengal, Odisha, Madhya Pradesh, Gujarat, Rajasthan) records ~50% higher chance of rainfall exceeding 200 mm/day during El Niño years compared to La Niña years.

• Such events increase the risk of flash floods, waterlogging, and landslides.

Empirical Evidence from Data

• Source: India Meteorological Department (IMD) rainfall records (1901–2020).

• Findings:

  • Light and moderate rainfall decreased during El Niño summers.

  • Probability of extreme daily rainfall (>200 mm) increased by more than 50% in wetter regions.

• Interpretation: El Niño redistributes rainfall intensity rather than reducing it uniformly.

Regional Variations in Impact

1. Drier Zones (Rajasthan, Deccan Plateau):

   • Experience fewer rainy days and weaker showers.

   • Agriculture and water scarcity worsen.

2. Wetter Zones (Eastern, Central, and Coastal India):

   • Witness fewer rainfall days but more intense storms.

   • Vulnerable to flash floods, urban flooding, and crop damage.

Socio-Economic Implications

• Agriculture: Reduced seasonal rainfall harms kharif crops, but sudden extreme downpours can also damage standing crops and soil fertility.

• Water Resources: Erratic distribution complicates irrigation planning and reservoir management.

• Urban Planning: Intensified rainfall in cities leads to severe waterlogging, infrastructure strain, and public health risks.

• Disaster Preparedness: Flood-prone states face increased vulnerability during El Niño years, requiring robust mitigation measures.

Policy and Preparedness Measures

1. Improved Forecasting:

   • Enhance IMD’s predictive models for location-specific extreme rainfall events.

2. Disaster-Resilient Infrastructure:

   • Urban drainage, flood control, and embankments must be upgraded.

3. Agricultural Adaptation:

   • Promote climate-resilient cropping patterns, efficient irrigation, and crop insurance schemes.

4. Water Management:

   • Reservoirs and dams must be managed to balance drought and flood risks.

5. Community Awareness:

   • Localized warnings and preparedness campaigns can reduce damage to lives and property.

Conclusion

El Niño’s influence on the Indian monsoon is complex and multifaceted. While it weakens overall monsoon rainfall, it paradoxically raises the likelihood of extreme daily downpours in wetter regions. This phenomenon underscores the necessity for India to adopt a nuanced climate-resilient strategy that goes beyond average rainfall projections. With climate change likely amplifying such extremes, proactive policies in forecasting, agriculture, urban planning, and disaster management are critical for safeguarding livelihoods and infrastructure.

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