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El Nino and India

2023 JUN 19

Mains   > Geography   >   Climatology   >   Climatology


  • Recently, the U.S. National Oceanic and Atmospheric Administration (NOAA) declared that an El Nino is now underway.


  • The current El Nino event is the fifth since 2000.
  • In India, the El Nino results in suppressed rainfall during the monsoon season.


  • El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
  • El Niño is the “warm phase” of a larger phenomenon called the El Niño-Southern Oscillation (ENSO).
  • La Niña, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of surface waters in the eastern tropical Pacific Ocean.
  • El Niño and La Niña are considered the ocean part of ENSO, while the Southern Oscillation is its atmospheric changes.
  •  El Niño and La Niña events occur every two to seven years, on average, but they don’t occur on a regular schedule.
  • Generally, El Niño occurs more frequently than La Niña.

Southern Oscillation (SO):

  • The interaction of the atmosphere and ocean is an essential part of El Niño and La Niña events.
  • During an El Niño, sea level pressure tends to be lower in the eastern Pacific and higher in the western Pacific while the opposite tends to occur during a La Niña.
  • This see-saw in atmospheric pressure between the eastern and western tropical Pacific is called the Southern Oscillation, often abbreviated as simply the SO.



What happens during normal years?

  • A surface low pressure develops in the region of northern Australia and Indonesia and a high-pressure system over the coast of Peru.
  • As a result, the trade winds over the Pacific Ocean move strongly from east to west.
  • These carry warm surface waters westward, bringing convective storms (thunderstorms) to Indonesia, coastal Australia, and India.


What happens during El Nino years?

  • Air pressure drops over large areas of the central Pacific and along the coast of South America.
  • The normal low pressure system is replaced by a weak high pressure system in the western Pacific.
  • This results in the trade winds to be reduced and accumulation of Warm Ocean water along the coastlines of Peru and Ecuador.


What happens during La Niña years?

  • The equatorial winds are much stronger than usual. This bring more warmer waters to the western margins.
  • This means that places like Indonesia and Australia can get much more rain than usual (rain clouds normally form over warm ocean water).
  • However, the cold water in the eastern Pacific causes less rain clouds to form there. So, places like the southwestern United States can be much drier than usual.



  •  El Nino and Indian monsoon:
    • El Nino and Indian monsoon are generally inversely related.
    • According to statistics, about 60 percent of the time there will be a probability of drought in India during an El Niño year, say experts.
    • The chances of below-normal rain will be 30 percent, while the prospect of normal rain remains very rare at 10 percent, they add.
    • However, El Niño conditions have been known to be unpredictable as well, climate experts admit.
    • For instance, even the strongest El Niño has given normal Monsoon rains of 102 per cent in 1997, while weak El Niño conditions resulted in severe drought in 2004 to the tune of 86 per cent.
  • Droughts: 
    • According to a 2014 ICRIER (Indian Council for Research on International Economic Relations) paper on El Nino and Indian droughts by Ashok Gulati and others, not all El Nino years resulted in droughts (where rainfall falls below 10% of the long-term average) for India, but the majority of droughts occurred during El Nino years.
    • The paper observes that there is a higher chance of an El Nino turning into a drought if the warming of the oceans were to occur between April and November, rather than between October and April.
  • Impact on agriculture: 
    • During El Nino phases normal precipitation patterns to get disrupted, leading to extreme climate events.
    • Experience in the past shows that globally, agricultural production is affected, including in India.
    • The immediate issue of concern is the prospects of the kharif crop during an El Nino event.
    • This is so because on an average around 60 per cent of the crop is rainfall dependent, and hence any deviation can harm prospects.
    • As the kharif crop is approximately 50 per cent of total agricultural output, the magnitude is serious.
    • The table given below shows how agricultural production (as per GDP data) has moved when there have been episodes of El Nino, 2015-16 being the larger one.
      • The last strong El Nino event was in the period 2014-16. There have, however, been less severe ones in this century after the strong event in 1997-98. We had a smaller event last in 2018-19.


As climate change is expected to increase its foothold over global climate, El Nino events are poised to become more frequent in the coming years. An El Nino event is not a certainty, yet the government should be prepared for it.

  • Short term: Since El Nino predictions are not fully reliable; the ideal strategy in the short run would be to improve upon the pillars of preparedness, response and mitigation. This can be achieved through:
    • Regular weather forecasting and periodic warnings.
    • The IMD could study the past patterns of El Nino and indicate the regions that would be most vulnerable.
    • Expanding farm insurance cover as a safety net for farmers.
    • States should provide consultancy services to the farmers to be prepared for such an adversity and advice on cropping action.
    • To buffer against a possible shortfall in output of some prime commodities, there should be contingency plans in place such as sourcing imports.
    • Strengthen Public distribution systems
    • The government needs to ensure that banks are sensitive to this issue so that credit flow to farmers remains uninterrupted.
  • Long term:
    • Encourage research and infrastructural investments in the field of meteorology so as to develop more reliable forecasting systems.
    • Encourage efficient agricultural practices like micro irrigation, use of water-stress resilient crops, development of storage facilities etc.
    • Improve upon India’s drought and flood mitigation measures.
    • Strengthening community watershed management and development.


Q. Explain the mechanism of El Nino. Also discuss the probable impacts of El Nino on India?