LA-NINA (Syllabus GS Paper 1 – Geography)

Context: Global models mis predicted La Nina's onset, leading to significant forecasting errors. The delay in La Nina's arrival has substantial implications for climate predictions and related impacts.

La-Nina

• Definition: La Niña, meaning ‘The Little Girl’ in Spanish, is a phase of the El Niño Southern Oscillation (ENSO), a significant climate driver.
• ENSO: It involves fluctuations in sea temperatures in the tropical Pacific Ocean, affecting global atmospheric circulation and weather patterns.
• Phases of ENSO: It has three phases: warm (El Niño), cool (La Niña), and neutral. Each phase influences global weather differently.
• Neutral Phase Conditions: During the neutral phase, the eastern Pacific is cooler than the western Pacific due to the movement of trade winds and upwelling of cooler waters.
• El Nino Phase Conditions: In El Niño, trade winds weaken, leading to warmer sea temperatures in the eastern Pacific and less displacement of warm water.
• La Nina Phase Conditions: In La Niña, trade winds strengthen, pushing more warm water to the western Pacific and making the eastern Pacific cooler.
• Impact on India: La Nina is known to enhance monsoon activity in India, whereas El Niño often suppresses it.
• Recent Events: The most recent El Niño occurred from June 2023 to May 2024, while one of the longest La Niña episodes lasted from 2020 to 2023.

Impact of Delayed La Nina Onset on India's Monsoon

• Role in Monsoon La Nina typically boosts rainfall during India's southwest monsoon season, which runs from June to September.
• Current Status of La Nina: As the monsoon season nears its end, La Niña conditions have not yet emerged in the equatorial Pacific Ocean, meaning it will not directly influence the current rainfall.
• Factors Affecting Rainfall: Other climatic factors beyond La Niña also impact monsoon rainfall, so a delayed onset does not necessarily predict poor monsoon performance.
• Regional Variations: Eastern and northeastern India, along with parts of the north and northwest, have seen deficient rainfall, while central and southern India have enjoyed more than normal precipitation.