EL NINO-SOUTHERN OSCILLATION (Syllabus: GS Paper 3 - Env & Eco)

Context: The world could see more multi-year El Nino and La Nina events due to human activities, according to a new study published in Nature journal.

• El Nino and La Nina are the warm phase and cool phases of a recurring climate pattern across the tropical Pacific Ocean called the El Nino-Southern Oscillation (ENSO). 

• In 2023, La Nina ended its three-year run and El Nino announced its arrival. 
• The atmospheric component of ENSO driving weather patterns across the world, has changed its behaviour since the industrial era.

El Nino

• About: It is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru. El Niño events occur irregularly at intervals of 2–7 years, although the average is about once every 3-4 years.

• After El Nino event weather conditions usually return back to normal.
• However, in some years the trade winds can become extremely strong and an abnormal accumulation of cold water can occur in the central and eastern Pacific. This event is called a La Niña.

• Impact on monsoon rainfall in across the globe: El Nino impacts ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather from Australia to South America and beyond.

• Rainfall increases drastically in South America, contributing to coastal flooding and erosion.

• Impacts on monsoon rainfall in India: El Nino and Indian monsoons are inversely related.

• The most prominent droughts in India – six of them – since 1871 have been El Nino droughts, including the recent ones in 2002 and 2009
• However, not all El Nino years led to a drought in India. For instance, 1997/98 was a strong El Nino year but there was no drought (Because of IOD).
• On the other hand, a moderate El Nino in 2002 resulted in one of the worst droughts.

• El Nino directly impacts India’s agrarian economy as it tends to lower the production of summer crops such as rice, sugarcane, cotton, and oilseeds.