February 13, 2025

General Studies Paper -1

Context: The India Meteorological Department expects a La Niña to set in by late 2024 or early 2025, plus a milder winter due to this delay.

Emergence of La Nina

  • Historically, the La Niña has usually formed during the monsoon or the pre-monsoon period, and it has formed only twice between October and December since 1950.
  • Predicting La Nina: The oceanic Niño index (ONI) compares the three-month average sea surface temperatures in the East-Central Tropical Pacific with the 30-year average.
    • When the difference between the two is 0.5º C or higher, it is an El Niño, and when it is –0.5º C or lower, it is a La Niña.
  • Currently, it is around –0.3º C. To be classified as a full-fledged La Niña or El Niño, ONI values need to exceed the thresholds at least five times consecutively.

What is La Nina?

  • It means Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply “a cold event.”
  • The trade winds become stronger than usual, pushing more warmer waters towards the Indonesian coast, and making the eastern Pacific Ocean colder than normal.
  • Impact on Weather Patterns:
  • North America: La Niña is often associated with colder winters in the northern U.S. and Canada and warmer, drier conditions in the southern U.S. (such as in the southwestern states).
  • South America: La Niña often causes droughts in countries like Peru and Ecuador while bringing more rain to Brazil.
  • Asia and Oceania: La Niña tends to bring increased rainfall and a higher risk of flooding to countries like Indonesia, Australia, and parts of Southeast Asia.

Impact on India

  • More rainfall in most regions, leading to a stronger monsoon.
  • Increased risk of flooding and waterlogging in many parts of the country.
  • Cooler temperatures during the post-monsoon and winter months.
  • More cyclones in the Indian Ocean, increasing risks for coastal areas.
  • Possible agricultural disruptions due to heavy rainfall, floods, and delayed harvesting.

Conclusion

  • Climate change may increase the frequency and intensity of both La Niña and El Niño events, as rising sea and land temperatures disrupt the Pacific’s balance.
  • Thus it would be a welcome development if a La Niña forms now or early next year and continues until the monsoon season. This would mean a less intense summer and more rains for India.
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