EL NINO PHENOMENON

1. Context

2. What is the El Nino Phenomenon?

• El Nino is the warming of seawater in the central East Equatorial Pacific that occurs every few years. During El Nino surface temperatures in the Equatorial Pacific rise, and trade winds-east-west winds that blow near the Equator -Weaken.
• Normally, easterly trade winds blow from the Americas towards Asia. Due to El Nino, they falter and change direction to turn into westerlies, bringing warm water from the western Pacific towards the Americans.
• The Phenomenon of upwelling, where nutrient-rich waters rise towards the surface, is reduced under El Nino.
• This in turn reduces phytoplankton. Thus Fish that eat phytoplankton are affected, followed by other organisms higher up the food chain. Warm waters also carry tropical species towards colder areas, disrupting multiple ecosystems.
• Since the Pacific covers almost one-third of the earth, changes in its temperature and subsequent alteration of wind patterns disrupt global weather patterns.
• El Nino causes dry, warm winters in the Northern U.S. and Canada and increases the risk of flooding in the U.S. gulf coast and southeastern U.S. It also brings drought to Indonesia and Australia.

3. What is La Nina?

• La Nina is the opposite of El Nino. La Nina sees cooler than average sea surface temperature (SST) in the equatorial pacific region. Trade winds are stronger than usual, pushing warmer water towards Asia.
• On the American west coast, upwelling increases, bringing nutrient-rich water to the surface. Pacific Cold waters close to the Americas Push jet streams-narrow bands of strong winds in the upper atmosphere-northwards.
• This leads to drier conditions in the Southern U.S., and heavy rainfall in Canada.
• La Nina has also been associated with heavy floods in Australia. Two successive La Nina events in the last two years caused intense flooding in Australia, resulting in significant damage.

4. Findings of the study of El Nino and La Nina

• The combination of El Nino, La Nina, and a neutral state between the two opposite effects is called the El Nino Southern Oscillation (ENSO). Southern oscillations are large-scale changes in sea level pressure in the tropical pacific region.
• ENSO's Scale is significant enough to influence global climate. According to the study, published in the Nature Communications journal, increased SST variability from ENSO in the eastern Equatorial Pacific (EP) will emerge around 2030 ( error margin of +/- 6 years), more than a decade earlier than that of the central pacific (CP) ENSO.
• If CP and EP are not separated, SST variability from ENSO will occur almost four decades earlier than previously suggested.
• Changes in the equatorial Pacific will be visible first due to a stronger increase in the EP-ENSO rainfall response, leading to increased SST variability.

5. Effect on India's Monsoon

• In India, El Nino causes weak rainfall and more heat, while La Nina intensifies rainfall across South Asia, particularly in India's northwest and Bangladesh during the monsoon. At present, India, like the rest of the globe is witnessing an extended 'triple dip' La Nina.
• India is a farm-based country, and around 50% of its area is under cultivation. Also, the Indian agricultural system largely depends on the strength of monsoons and the quantity of precipitation. Hence La Nina's condition is muchly favorable for Indian agriculture and the economy at large. In this way, a La Nina effect will create sufficient precipitation in India, directly boosting the farm produce.
• On the other hand, heavy rainfall sometimes creates floods in some areas, adversely affecting people's lives and the economy. The larger farm produces will enhance the economic growth of the country.
• However, El Nino during the winter causes warm conditions over the Indian subcontinent and dry and deficient monsoons during summer. Hence, it creates a draught-like situation and affects agriculture. The Crops like Paddy, Groundnut, Maize, Guar, Castor, Moong, Tur, and Bajra suffer greatly from El Nino conditions.

For Prelims & Mains