SYLLABUS
GS-1: Salient features of World’s Physical Geography; Important Geophysical Phenomena.
GS-3: Conservation, environmental pollution and degradation, environmental impact assessment.
Context: Global climate models indicate a rising probability of El Niño conditions emerging in the second half of 2026, marking a potential shift in the El Niño–Southern Oscillation (ENSO) cycle.
More on the News
• The National Oceanic and Atmospheric Administration (NOAA) in its latest El Niño–Southern Oscillation (ENSO) bulletin has projected that there is about 62% chance that El Niño may emerge during June–August 2026 and is likely to persist till the end of 2026.
• The India Meteorological Department (IMD) has also indicated that El Niño may occur after July this year, but clarity will only emerge in April.
• The latest climate models show a greater than 50% chance of an El Niño appearing over India after June and increasing to nearly 70% during July, August, and September.
• El Niño’s timing could coincide with India’s core monsoon months (June–September), when about 70% of annual rainfall occurs, heightening vulnerability for rainfed agriculture.
• Past cycles show ENSO events recur every 2–7 years. Historically, around 60% of El Niño years have been linked to below-normal rainfall in India.
- The last major El Niño (2023–24) correlated with below-normal Indian monsoon rains.
About El Niño and La Niña
• ENSO (El Niño–Southern Oscillation) is a periodic climate phenomenon involving changes in sea surface temperatures (SSTs) and atmospheric circulation in the equatorial Pacific Ocean.
• Normal Conditions
- Trade winds blow from east to west along the equator.
- Warm water accumulates in the western Pacific, while cold, nutrient-rich water upwells near South America.
• El Niño Phase (Warm Phase)
- Trade winds weaken or reverse.
- Warm waters shift eastward toward the central and eastern Pacific.
- Upwelling reduces, disrupting global atmospheric circulation.
- Defined when SSTs rise by at least 0.5°C above normal for sustained periods.
• La Niña Phase (Cool Phase)
- Trade winds strengthen.
- Enhanced upwelling leads to cooler-than-normal SSTs in the eastern Pacific.
- Reinforces normal circulation patterns.
Impact of El Niño
• Global:
- El Niño years are often among the warmest on record due to additional oceanic heat release.
- It alters Walker Circulation, causing droughts in India/Australia/Indonesia, floods in the Americas, and heatwaves worldwide.
- The Walker Circulation (or Walker cell) is a major east-west atmospheric circulation pattern in the tropics, driven by surface temperature differences across the Pacific Ocean.
- Reduced upwelling affects fish stocks and marine biodiversity, especially in the Pacific.
• Impacts on India:
- El Niño is often associated with below-normal southwest monsoon rainfall, affecting kharif crops like rice and pulses.
- Reduced rainfall may lead to lower crop yields, higher irrigation demand, and rural distress.
- Intensification of summer heatwaves, especially in north and central India.
- Lower agricultural output can lead to food inflation, affecting overall macroeconomic stability. Reduced rainfall impacts reservoir levels, groundwater recharge, and drinking water availability.
SOURCES
India Express
The Hindu
CPC