Source: IT
Subject: Geography
Context: Researchers at Duke University have identified that ocean salinity can amplify the intensity of El Niño by approximately 20%.
About El Nino:
What it is?
- El Niño (meaning “Little Boy” in Spanish) is a recurring climate pattern characterized by the unusual warming of surface waters in the central and eastern tropical Pacific Ocean. It is the warm phase of the El Niño-Southern Oscillation (ENSO) cycle and typically occurs every two to seven years.
How it Forms?
- Normal Conditions: Strong trade winds blow from east to west along the equator, pushing warm surface water toward Asia. This allows cold, nutrient-rich water to rise (upwelling) near the coast of South America.
- Weakening Winds: During El Niño, these trade winds weaken or even reverse direction.
- Warm Water Shift: The warm water that was piled up in the western Pacific begins to flow back eastward toward the Americas.
- Atmospheric Disruption: This shift in heat alters the Pacific jet stream, disrupting global weather patterns, leading to floods in some regions and droughts in others.
Factors Influencing El Niño:
- Trade Wind Strength: The primary driver; weaker winds trigger the eastward movement of warm water.
- Ocean-Atmosphere Coupling: A feedback loop where warming water further weakens winds, which in turn warms the water more.
- Thermocline Depth: The depth of the transition layer between warm surface water and cold deep water influences how much heat is available to fuel the event.
- Rossby and Kelvin Waves: Large-scale internal ocean waves that transport heat across the Pacific.
Implications for India:
A stronger El Niño directly impacts India’s food and water security:
- Monsoon Suppression: It pulls moisture away from South Asia, frequently resulting in below-normal rainfall.
- Drought Risk: There is a 60% likelihood of drought in various regions during a strong El Niño year.
- Agricultural Impact: Drier conditions lead to food grain shortfalls, as seen in 2023, which saw the driest August in years and triggered food inflation.
- Heatwaves: El Niño often correlates with higher-than-average temperatures and prolonged heatwaves during the Indian summer.
