Q. “The Indian monsoon is increasingly influenced by a complex interplay of ENSO, Indian Ocean Dipole (IOD), and climate change.” Critically...

Q. “The Indian monsoon is increasingly influenced by a complex interplay of ENSO, Indian Ocean Dipole (IOD), and climate change.” Critically examine. (15 marks)

Model Answer

Q.“The Indian monsoon is increasingly influenced by a complex interplay of ENSO, Indian Ocean Dipole (IOD), and climate change.” Critically examine.(15 marks)

Paper

GS I

Subject

Indian Geography

Syllabus as Per Notification

Salient Features of World's Physical Geography

Topic

Indian Monsoon, ENSO (El Niño–Southern Oscillation), Indian Ocean Dipole (IOD), Climate Change, Monsoon Variability, Extreme Weather Events, Climate Resilience

Approach:

Introduction

Define the Indian monsoon as a crucial climatic phenomenon and briefly mention the traditional role of ENSO in influencing monsoon variability.

Introduce IOD and climate change as emerging factors that increasingly shape monsoon behaviour.

Establish the demand of the question by stating that monsoon outcomes now result from the interaction of multiple climatic drivers rather than a single factor.

Body

Explain how ENSO influences the Indian monsoon, highlighting both its significance and limitations as a predictor.

Examine the role of IOD in amplifying or offsetting ENSO's effects, supported by suitable examples.

Analyse how climate change is altering monsoon dynamics through Indian Ocean warming, extreme rainfall events, heatwaves and increased variability.

Critically examine why forecasting has become more challenging due to weakening ENSO-monsoon linkages, altered teleconnections and the emergence of multi-factor monsoon dynamics.

Conclusion

Conclude that the Indian monsoon can no longer be explained solely through the ENSO framework and is increasingly shaped by the combined influence of ENSO, IOD and climate change.

Emphasise that this growing complexity demands more sophisticated forecasting models and adaptive policy responses.

Introduction

The Indian Summer Monsoon contributes nearly 75% of India's annual rainfall and is crucial for agriculture, water security, food security and economic stability. While ENSO (El Niño-Southern Oscillation) has traditionally been the primary driver of monsoon variability, recent decades have witnessed the growing influence of the Indian Ocean Dipole (IOD) and climate change. The emergence of a moderate-to-strong El Niño in 2026, along with neutral IOD conditions and rising global temperatures, highlights the increasingly complex nature of monsoon dynamics.

Body

ENSO as a Major Driver of Indian Monsoon Variability

Influence of ENSO on the Indian Monsoon

  • The

    El Niño-Southern Oscillation (ENSO)

    , characterised by periodic warming (El Niño) and cooling (La Niña) of sea surface temperatures in the equatorial Pacific Ocean, remains one of the most important drivers of Indian monsoon variability.

  • During El Niño conditions, the weakening of the

    Walker Circulation

    reduces the flow of moisture-laden winds towards the Indian subcontinent, often resulting in below-normal monsoon rainfall.

  • This leads to reduced soil moisture, lower groundwater recharge, declining reservoir levels and adverse impacts on agricultural productivity.

  • Several major drought years, including

    2002, 2009, 2015 and 2023

    , coincided with El Niño events, highlighting its significant influence on India's rainfall patterns.

  • The ongoing

    2026 El Niño

    has prompted IMD to revise monsoon rainfall forecasts to

    90% of LPA

    , with below-normal rainfall expected in key rain-fed agricultural regions.

Limitations of ENSO as a Predictor

  • ENSO alone cannot fully explain monsoon behaviour, as several El Niño years have not resulted in severe droughts.

  • Regional rainfall distribution often differs significantly from all-India rainfall averages.

  • Recent studies suggest that the ENSO-monsoon relationship has weakened over time due to the growing influence of the

    Indian Ocean Dipole (IOD)

    , Indian Ocean warming and climate change.

  • Therefore, while ENSO remains a critical determinant of monsoon variability, its impact is increasingly shaped by interactions with other climatic drivers.

Role of the Indian Ocean Dipole (IOD)

The Indian Ocean Dipole (IOD) refers to the difference in sea surface temperatures between the western and eastern Indian Ocean and acts as an important modifier of monsoon rainfall over India. While ENSO influences monsoon conditions from the Pacific Ocean, the IOD can either amplify or offset its effects, making it a crucial determinant of monsoon outcomes.

Positive IOD: A Buffer Against Monsoon Deficits

  • During a positive IOD, warmer waters in the western Indian Ocean and cooler waters near Indonesia enhance moisture transport towards India.

  • This strengthens monsoon circulation and increases rainfall over large parts of the country.

  • A favourable positive IOD can partially or even completely offset the adverse effects of El Niño.

  • For instance, despite experiencing one of the strongest El Niño events in

    1997

    , India avoided a severe drought due to the presence of a strong positive IOD.

Negative IOD: Intensifying Monsoon Weakness

  • During a negative IOD, warmer waters in the eastern Indian Ocean weaken moisture transport towards the Indian subcontinent.

  • This suppresses monsoon rainfall and increases the likelihood of drought conditions.

  • When a negative IOD coincides with El Niño, the risk of widespread rainfall deficiency becomes significantly higher.

Growing Influence of Climate Change on Monsoon Dynamics

· Rapid Warming of the Indian Ocean

  • The Indian Ocean is warming faster than the global average.

  • Rising sea surface temperatures and marine heatwaves are altering atmospheric circulation, moisture transport and cloud formation.

  • Consequently, Indian Ocean warming is emerging as an independent driver of monsoon variability.

· Increase in Extreme Rainfall Events

  • Climate change is altering the nature of rainfall, making it more intense, concentrated and spatially uneven.

  • Short-duration extreme rainfall events have increased, causing floods, flash floods and landslides even during years of normal seasonal rainfall.

· Weakening Predictability of ENSO-Monsoon Linkages

  • Climate change has altered traditional ocean-atmosphere teleconnections.

  • Similar ENSO conditions now produce different monsoon outcomes compared to the past.

  • This has reduced the reliability of monsoon forecasts based solely on ENSO indicators.

· Increased Heatwaves and Temperature Extremes

  • El Niño combined with global warming contributes to more severe heatwaves.

  • Heat stress affects crop productivity, water availability, labour efficiency and public health.

  • NOAA and WMO have warned that the emerging

    "Super El Niño"

    could make

    2027 one of the hottest years on record

    .

Why Monsoon Forecasting Has Become More Challenging

· Declining Dominance of ENSO

  • ENSO remains important but no longer singularly determines monsoon outcomes.

  • Its predictive power has weakened due to the growing role of other climatic drivers.

    • For instance, despite a strong El Niño in

      1997

      , India avoided a major drought, while some non-El Niño years have witnessed significant rainfall deficiencies.

· Increasing Influence of IOD

  • The impact of El Niño is increasingly moderated by IOD conditions.

  • Similar El Niño events may produce different rainfall outcomes depending on the prevailing IOD phase.

· Climate Change and Altered Teleconnections

  • Climate change has modified historical ocean-atmosphere interactions.

  • Forecasting models based on past climatic relationships face increasing uncertainty.

· Indian Ocean Warming as an Independent Driver

  • Rising sea surface temperatures and marine heatwaves influence monsoon circulation independent of ENSO.

  • This introduces an additional layer of complexity into forecasting.

· Growing Frequency of Extreme Weather Events

  • Seasonal rainfall may remain near normal, but its distribution across time and space has become highly uneven.

  • Aggregate rainfall statistics often fail to capture actual agricultural and hydrological impacts.

    • Recurrent urban floods such as the

      2018 Kerala floods

      ,

      2023 Himachal Pradesh floods

      ,

      and in Mumbai and Bengaluru illustrate how extreme rainfall can occur even during normal monsoon years.

· Emergence of Multi-Factor Monsoon Dynamics

  • Monsoon outcomes increasingly result from the interaction of ENSO, IOD, Indian Ocean warming and climate change rather than any single phenomenon.

  • For instance, a strong El Niño may not lead to drought if accompanied by a favourable positive IOD.

  • Conversely, climate change may trigger extreme rainfall and floods even during years of below-normal monsoon rainfall.

Conclusion

The Indian monsoon can no longer be understood solely through the lens of ENSO, as its behaviour is increasingly shaped by the interaction of ENSO, IOD, Indian Ocean warming and climate change. The ongoing 2026 El Niño episode highlights the growing complexity and uncertainty surrounding monsoon dynamics. Therefore, strengthening climate-resilient agriculture, advanced forecasting systems, adaptive water management and district-level contingency planning is essential to ensure India's food, water and economic security in an era of increasing climatic variability.