El Nino - An Overview

El Nino is an important phenomenon. In this article, one can understand what an El Nino is, how it occurs due to changes in surface temperature of the Pacific Ocean off the coast of Peru, its effects in general and its effect in India. This is an important topic from the perspective of Geography syllabus in the UPSC Exam.

Aspirants would find this article very helpful while preparing for the IAS Exam.

El Nino – How Does it Occur?

El Nino can be understood as a natural phenomenon wherein the ocean temperatures rise especially in parts of the Pacific ocean. It is the nomenclature which is referred to for a periodic development along the coast of Peru. This development is a temporary replacement of the cold current along the coast of Peru.   El Nino is a Spanish word. The term El Nino basically means ‘the child’. This is due to the fact that this current starts to flow around Christmas and hence the name referring to baby Christ.   Another natural phenomenon, similar to El Nino is the La Nina, which is also in news these days. The term La Nina literally means ‘ little girl’. It is termed as opposite to the phenomenon of El Nino as it results in the ‘cooling’ of the ocean water in parts of the Pacific ocean.   Both of them also result in the changes in atmospheric conditions along with the oceanic changes.

El Nino Southern Oscillation (ENSO) 

It is called El Nino Southern Oscillation. In normal times, when the tropical south Pacific ocean experiences high pressure, alternatively the tropical Indian ocean experiences low pressure conditions.   However, these pressure conditions are sometimes reversed, and results in low pressure in the Pacific and alternatively high pressure in the Indian ocean. This is the periodic change in pressure conditions which is referred to as the Southern Oscillation.   These changes in the pressure conditions being developed in the Pacific and Indian oceans are connected with the phenomenon of El Nino. This connected phenomenon is referred to as the El Nino Southern Oscillations or the ENSO.

El Nino – Effects on India

In a normal monsoon year (without El Nino), the pressure distribution is as follows:

  1. The coast of Peru in South America has a higher pressure than the region near northern Australia and South East Asia.
  2. The Indian Ocean is warmer than the adjoining oceans and so, has relatively lower pressure. Hence, moisture-laden winds move from near the western Pacific to the Indian Ocean.
  3. The pressure on the landmass of India is lower than on the Indian Ocean, and so, the moisture-laden winds move further from the ocean to the lands.

If this normal pressure distribution is affected for some reason, the monsoons are affected.

El Nino Effects

  1. El Nino results in the rise of sea surface temperatures
  2. It also weakens the trade winds of the affected region
  3. In India, Australia, it can bring about drought conditions. This affects the crop productivity largely. It has been also observed certain times, that EL Nino may not bring drought but cause heavy rainfall. In both the cases, it causes heavy damage.
  4. However, in some other countries it may result in a complete reversal, i.e., excessive rainfall.

  Mitigation OF  Effects:

  1. Keeping a check on the sea surface temperatures
  2. Maintaining sufficient buffer stocks of food grains and ensuring their smooth supply
  3. Ensuring relevant support to the farmer community including economic help
  4. Alternative ways to be promoted such as the practice of sustainable agriculture


The above details would help candidates prepare for UPSC 2020.

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