El Nino and La Nina
El Niño and La Niña are ocean-atmosphere phenomena that occur in the Pacific Ocean, but significantly influence global climate patterns, including the Indian monsoon.
- Part of the ENSO (El Niño Southern Oscillation) cycle
- Affect agriculture, rainfall, and temperature in India
📝 PYQ (BPSC 66th): El Niño is associated with what? → Warming of Pacific Ocean
🌡️ What is El Niño?
- El Niño = Unusual warming of central & eastern tropical Pacific Ocean
- Occurs every 2 to 7 years
- Weakens trade winds and monsoon circulation
🔴 Effects of El Niño in India:
- Deficient monsoon rainfall
- Drought-like conditions, especially in central & north India
- Poor agricultural output (especially Kharif crops)
- Can lead to food inflation
📝 Expected BPSC MCQ: El Niño causes what effect in India? → Weak monsoon
❄️ What is La Niña?
- La Niña = Unusual cooling of central & eastern Pacific Ocean
- Strengthens trade winds
- Enhances Indian Ocean monsoon flow
🔵 Effects of La Niña in India:
- Heavy monsoon rains
- Floods in some regions
- Sometimes beneficial for agriculture (if moderate)
📝 Expected BPSC MCQ: La Niña is associated with? → Enhanced rainfall in India
🔁 ENSO (El Niño Southern Oscillation)
- The combined name for El Niño and La Niña effects
- Includes changes in atmospheric pressure, wind patterns, and ocean temperatures
- Measured by Southern Oscillation Index (SOI)
🌾 Impact on Agriculture in India
- Kharif crops (Paddy, maize, cotton) depend heavily on monsoon
- El Niño years → poor rainfall → reduced output
- La Niña → excess rains → can benefit or flood crops
📝 Expected MCQ: Which crop is most affected by El Niño-induced drought? → Paddy
📊 El Niño Years and Drought in India (Examples)
- 1982, 1987, 2002, 2009, 2015 – Major El Niño years with droughts
- La Niña in 2010, 2011, 2020 led to heavy rainfall
Bihar-Specific Impact
- Bihar’s agriculture is monsoon-dependent (~80% of farmers)
- El Niño leads to:
- Delayed sowing
- Low paddy yield
- Risk to food security and employment
- Government initiates contingency crop plans in El Niño years
📌 Quick Recap
- El Niño → Warm Pacific, weak monsoon, drought in India
- La Niña → Cool Pacific, strong monsoon, possible floods
- Kharif crops most impacted
- Bihar’s paddy production vulnerable to El Niño
📚 Sources Used
- IMD (India Meteorological Department)
- NCERT Geography – Class 11 India Physical Environment
- Bihar Economic Survey 2024–25
- Drishti Bihar Special
- Ghatna Chakra BPSC PYQs