El-Nino and La Nina

El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the El Nino-Southern Oscillation (ENSO) cycle.

El Nino

El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean. It is the warm phase of the El Niño-Southern Oscillation (ENSO) cycle, which is a naturally occurring climate phenomenon that occurs every 2-7 years.

• Mechanism

• Trade winds: During an El Niño event, the trade winds that normally blow from east to west weaken and the cold Peruvian current is replaced by warm El Nino current. 

• Warm water in eastern pacific: Warm water that is normally held in the western Pacific Ocean sloshes eastward. This warm water causes the sea surface temperatures in the eastern Pacific Ocean to rise by 2-3 degrees Celsius above normal.

• Upwelling in the east: In the eastern Pacific, upwelling occurs, bringing cold, nutrient-rich waters to the surface. This supports high marine productivity.

• Effect of El-Nino:

• Global temperature changes: Elevated sea surface temperatures during El Niño contribute to increased global temperatures, affecting weather patterns across continents.

• Droughts and heat waves:  Brings drier conditions to eastern Australia leading to reduced rainfall and drought like conditions.

• Disruption of Fisheries: Changes in ocean temperatures and currents during El Niño can disrupt marine ecosystems, affecting fish migration patterns and reducing fish stocks, impacting fisheries.

• Impact on Ocean: El Nino also 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.

• Effect on Latin America: On the other hand in Latin American coast, it brings heavy rainfall and boost agricultural productivity in these regions.

• Disaster occurrence: The increased rainfall in Latin American coast can also lead to flooding and landslides, causing infrastructure damage and disrupting transportation.

• Positive impact: It can sometimes have a positive impact too, for example, El Nino reduces the instances of hurricanes in the Atlantic.

• Effect of El-Nino on India:

• On rainfall and monsoon: Results in reduced rainfall in India and weakens monsoon. 

• On agriculture: Reduced rainfall results in drought and thus effecting agriculture productivity

• Temperature increase and formation of cyclones: El Nino can also increase the temperature which will also have an impact on formation of Cyclones in Bay of Bengal region.

La Nina

La Niña is the cool phase of the El Niño-Southern Oscillation (ENSO) cycle. It is characterized by abnormally cool ocean temperatures in the equatorial Pacific Ocean. La Niña events typically last for 9-12 months and occur every 2-7 years.

• Mechanism

• Trade winds: During La Niña, trade winds that blow from east to west across the tropical Pacific Ocean blow stronger than normal, pushing warm surface water westward.

• Warm western pacific: Piled water in the western Pacific warms up and increase the sea surface temperature.

• Cooling eastern pacific: Upwelling brings cold water from the deep ocean to the surface, further cooling the eastern Pacific. Ocean-atmosphere interactions further intensify La Niña conditions.

• Effect of La Nina:

• In Europe: In Europe, la Nina increases the number of autumnal hurricanes.

• In North America: Favourable conditions for hurricanes in the Caribbean and central Atlantic area. There are chances for greater instances of tornados in various states of the US.

• Effect on Australia: La Niña typically brings increased rainfall to eastern and northern Australia.

• On environment: Alleviate drought conditions and boost agricultural productivity in Australian coast. It also results in cooler conditions in Australia.

• In Latin America: In Latin American region, La Nina causes upwelling which results in increased fish catch. It also results in cool but dry conditions in Latin America.

• Effect of La Nina in India

• On rainfall and monsoon: La Niña is typically associated with increased rainfall during the monsoon season in India. 

• On economy and agriculture: This can alleviate drought conditions and boost agricultural productivity. 

• On temperature and environment: La Niña can also cause slightly cooler temperatures in India, particularly during the monsoon season. This can reduce the risk of heatwaves and provide some relief from the heat.

Comparison- El Nino and La Nina