The India Meteorological Department (IMD) has forecasted above-normal rain in the upcoming monsoon season in India, with “favourable” La Nina conditions expected to set in by August-September.
About
El Niño and La Nina are climate phenomena that are a result of ocean-atmosphere interactions, which impact the temperature of waters in the central and eastern tropical Pacific Ocean.
El Niño events are far more frequent than La Nina ones. Once every two to seven years, neutral ENSO conditions get interrupted by either El Niño or La Nina.
Coriolis Effect: The Earth’s east-west rotation causes all winds blowing between 30 degrees to the north and south of the equator to slant in their trajectory.
As a result, winds in the region flow towards a southwesterly direction in the northern hemisphere and a northwesterly direction in the southern hemisphere. This is known as the Coriolis Effect.
Due to this, winds in this belt called trade winds blow westwards on either side of the equator. Page No.:- 30 Current Affairs –June, 2024
Normal Conditions: During normal conditions in the Pacific ocean, trade winds blow west along the equator, taking warm water from South America towards Asia.
To replace that warm water, cold water rises from the depths — a process called upwelling.
The warmer surface waters near Indonesia create a region of low-pressure area, causing the air to rise upwards. This also results in formation of clouds and heavy rainfall.
The air flow also helps in building up the monsoon system which brings rainfall over India.
La Niña:
It means Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply “a cold event.” La Niña has the opposite effect of El Niño.
The trade winds become stronger than usual, pushing more warmer waters towards the Indonesian coast, and making the eastern Pacific Ocean colder than normal.
Impacts
Increased rainfall: Regions such as Southeast Asia, northern Australia, and parts of South America often experience above-average rainfall during La Niña events.
Except in east and northeast India, all remaining regions are expected to receive normal or above seasonal rainfall during La Nina. • Similar to India, Indonesia, the Philippines, Malaysia and their neighbouring countries receive good rainfall during a La Nina year.
Drier conditions in some areas: Conversely, regions like the southwestern United States and parts of Africa experience below-average rainfall, leading to drought conditions.
Stronger Atlantic hurricanes: La Niña tends to reduce wind shear in the Atlantic, creating conditions that are more conducive to the development of hurricanes.
For instance, the Atlantic Ocean churned out a record 30 hurricanes during the La Nina year 2021.
Cooler temperatures: Some areas experience cooler temperatures than normal, particularly in the Pacific Northwest of the United States and parts of South America.
What is El Nino?
El Niño means Little Boy in Spanish. South American fishermen first noticed periods of unusually warm water in the Pacific Ocean in the 1600s.
It is a climate phenomenon characterized by the periodic warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean.
During El Niño, trade winds weaken. Warm water is pushed back east, toward the west coast of the Americas and as a result cold water is pushed towards Asia.
Impact of El Nino
Low Rainfall: El Niño often correlates with below-average monsoon rainfall in India, leading to droughts in many parts of the country. This can have severe consequences for agriculture, water resources, and the economy.
Increased Temperature: El Niño also lead to an increase in temperatures across various parts of India.
Forest Fires: The drier conditions associated with El Niño increase the risk of forest fires, particularly in regions with dense vegetation. These fires cause environmental damage, loss of biodiversity, and air pollution.
Water Scarcity: Decreased rainfall during El Niño events lead to water scarcity in many parts of India. This affect drinking water supplies, irrigation for agriculture, and hydropower generation.
Impact on Fisheries: El Niño also affect marine ecosystems and fisheries along India’s coastline. Changes in sea surface temperatures and ocean currents disrupt fish migration patterns and lead to fluctuations in fish populations.
Conclusion
Scientists say that climate change is set to impact the ENSO cycle. Many studies suggest that global warming tends to change the mean oceanic conditions over the Pacific Ocean and trigger more El Niño events.
The World Meteorological Organization (WMO) has also said that climate change is likely to affect the intensity and frequency of extreme weather and climate events linked to El Niño and La Nina
