El Niño, meaning “the little boy” in Spanish, was first recognized by Peruvian fishermen off the coast of Peru as the appearance of unusually warm water. It is the warmer- than-normal phase of the El Niño Southern Oscillation (ENSO) phenomenon, characterized by warmer temperatures and reduced rainfall in various regions, including India. During a strong El Niño event, Sea Surface Temperatures (SST) in the equatorial Pacific Ocean can be significantly warmer than the long-term average, reaching up to 3°C higher.

Connection between El Niño and the Indian Monsoon:

El Niño is a climate phenomenon that originates in the tropical Pacific Ocean but can have significant global impacts, including on the Indian monsoon.
● Pacific Ocean Warming: El Niño is characterized by the warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean. This warming disrupts normal atmospheric circulation patterns.

● Shift in Walker Circulation: During El Niño events, the Walker Circulation, which is a pattern of atmospheric circulation, weakens or reverses. Normally, the Walker Circulation brings moist air from the Indian Ocean to the western Pacific, aiding the Indian monsoon. During El Niño, this circulation weakens, reducing moisture transport to the Indian subcontinent.

● Weakened Indian Monsoon: The weakening of the Walker Circulation due to El Niño can result in a reduction in the intensity and duration of the Indian monsoon. This can lead to drought conditions, lower rainfall, and agricultural problems in parts of India.

● El Niño can result in heat waves, droughts, and hotter temperatures in regions like India, South Africa, Australia, Indonesia, and the Pacific Islands.

Impact of El Niño on World Climate:

El Niño has far-reaching impacts on global climate patterns, including:
● Shifted Rainfall Patterns: El Niño disrupts normal rainfall patterns worldwide. It can lead to droughts in some regions (e.g., India, Australia) and increased rainfall and flooding in others (e.g., South America).
● Warmer Global Temperatures: El Niño events contribute to higher global temperatures due to the release of heat stored in the tropical Pacific Ocean. This can exacerbate climate change effects.
● Hurricane Suppression: El Niño tends to suppress hurricane activity in the Atlantic Ocean but can increase the frequency and intensity of cyclones in the Pacific.
● Impacts on Agriculture: El Niño-related droughts and flooding can harm agriculture, leading to food shortages and economic losses in affected regions.
● Ecosystem Disruption: Marine ecosystems can be disrupted as El Niño affects sea surface temperatures, leading to coral bleaching, fishery changes, and altered migration patterns of marine species.

Impact of El Niño on Coral Reefs:

El Niño can have detrimental effects on coral reefs:
● Coral bleaching: El Niño raises sea temperatures, leading to coral bleaching. Corals expel their symbiotic algae when stressed by high temperatures, causing them to lose their color and eventually die if stress continues.
● Reduced Food Supply: El Niño’s altered oceanic conditions can reduce the availability of plankton, which is a primary food source for many reef organisms, including corals.
● Increased Storm Damage: El Niño can also lead to more frequent and severe storms, causing physical damage to coral reefs through wave action and sedimentation.
● Coral Mortality: Prolonged El Niño events can result in extensive coral mortality and hinder the recovery of reef ecosystems.
Note : Madden-Julian Oscillation

This comprises two distinct phases: an intensified rainfall phase and a diminished rainfall phase.
● In the intensified phase, surface winds converge, prompting air to ascend and generate increased rainfall.

● Conversely, during the diminished phase, atmospheric winds converge at higher altitudes, causing air to descend and resulting in reduced rainfall.
● This oscillating pattern moves from west to east across tropical regions, inducing increased cloudiness and rainfall during the intensified phase, while the diminished phase

brings about more sunshine and decreased precipitation.

El Niño’s influence on climate and ecosystems underscores its significance in global weather patterns and highlights the need for monitoring and understanding this phenomenon’s impacts. Climate change poses a grave threat, exacerbating the impacts of El Niño events. Hence urgent global action is essential to mitigate these compounding challenges and protect vulnerable ecosystems.

Legacy Editor Changed status to publish September 19, 2025