Recent forecasts by the India Meteorological Department (IMD) anticipate above-normal rainfall for the upcoming monsoon season, attributing this to the expected onset of favorable La Niña conditions by August-September. Concurrently, observations indicate a weakening in El Niño conditions since early this year.
EL NIÑO AND LA NIÑA AND ENSO:
El Niño and La Niña are crucial climate phenomena that form the El Niño-Southern Oscillation (ENSO) cycle.
El Niño, the "warm phase" of ENSO, involves unusual warming of surface waters in the eastern tropical Pacific Ocean.
La Niña, the “cool phase” of ENSO, is a pattern that describes the unusual cooling ofsurface waters in the eastern tropical Pacific Ocean.
El Niño and La Niña are considered the ocean part of ENSO, while the Southern Oscillation is its atmospheric changes.
El Niño and La Niña events occur every two to seven years, on average, but they don’t occur on a regular schedule.
Generally, El Niño occurs more frequently than La Niña.
Southern Oscillation (SO):
The interaction of the atmosphere and ocean is an essential part of El Niño and La Niña events.
During an El Niño, sea level pressure tends to be lower in the eastern Pacific and higher in the western Pacific while the opposite tends to occur during a La Niña.
This see-saw in atmospheric pressure between the eastern and western tropical Pacific is called the Southern Oscillation, often abbreviated as simply the SO.
MECHANSIM:
What happens during normal years?
A surface low pressure develops in the region of northern Australia and Indonesia and a high-pressure system over the coast of Peru.
As a result, the trade winds over the Pacific Ocean move strongly from east to west.
These carry warm surface waters westward, bringing convective storms (thunderstorms) to Indonesia, coastal Australia, and India.
What happens during El Nino years?
Air pressure drops over large areas of the central Pacific and along the coast of South America.
The normal low pressure system is replaced by a weak high pressure system in the western Pacific.
This results in the trade winds to be reduced and accumulation of Warm Ocean water along the coastlines of Peru and Ecuador.
What happens during La Niña years?
The equatorial winds are much stronger than usual. This bring more warmer waters to the western margins.
This means that places like Indonesia and Australia can get much more rain than usual (rain clouds normally form over warm ocean water).
However, the cold water in the eastern Pacific causes less rain clouds to form there. So, places like the southwestern United States can be much drier than usual.
EL NIÑO’S IMPACT ON INDIA:
El Nino and Indian monsoon:
El Nino and Indian monsoon are generally inversely related.
According to statistics, about 60 percent of the time there will be a probability of drought in India during an El Niño year, say experts.
The chances of below-normal rain will be 30 percent, while the prospect of normal rain remains very rare at 10 percent, they add.
However, El Niño conditions have been known to be unpredictable as well, climate experts admit.
For instance, even the strongest El Niño has given normal Monsoon rains of 102 per cent in 1997, while weak El Niño conditions resulted in severe drought in 2004 to the tune of 86 per cent.
Droughts:
According to a 2014 ICRIER (Indian Council for Research on International Economic Relations) paper on El Nino and Indian droughts by Ashok Gulati and others, not all El Nino years resulted in droughts (where rainfall falls below 10% of the long-term average) for India, but themajority of droughts occurred during El Nino years.
The paper observes that there is a higher chance of an El Nino turning into a drought if the warming of the oceans were to occur between April and November, rather than between October and April.
Impact on agriculture:
El Niño disrupts normal precipitation patterns, severely affecting agriculture. For example, the kharif crop, which constitutes about 50% of India's total agricultural output and relies heavily on rainfall, faces significant risks during El Niño. Data shows significant fluctuations in agricultural production during El Niño events, with notable impacts during the 2015-16 event.
LA NIÑA'S IMPACT ON INDIA:
Rainfall Patterns:
La Niña years often bring above-average rainfall to central and southern India, benefiting kharif crops but also increasing risks of flooding and landslides.
Agricultural Impact:
The enhanced rainfall can boost agricultural productivity, especially in water-intensive crops. However, excessive rainfall might cause issues like pest outbreaks and waterlogging.
Temperature Variations:
While La Niña typically cools the equatorial Pacific, it can result in warmer temperatures in parts of India, affecting crop cycles and energy use. For example, during the La Niña event of 2010-12, India experienced significant increases in rainfall leading to better yields in rice and wheat but also challenges with flooding and pests.
GLOBAL CLIMATIC IMPACT:
El Niño and La Niña have wide-reaching effects on global climate patterns, influencing weather conditions across continents with varying degrees of severity.
El Niño:
North America: In the southern regions, warmer winters with reduced precipitation exacerbate drought conditions, while the northern areas may experience unusually cold weather and storms.
South America: There is an increased risk of wildfires, particularly affecting the western and central regions due to dryer conditions.
Australia: The continent frequently faces severe drought conditions, impacting water reserves and agriculture significantly.
La Niña:
North America: The southern United States may experience drought and higher temperatures, whereas the northwest could see cooler temperatures and increased rainfall.
Africa: Southern Africa typically receives more rainfall, benefiting agriculture, while eastern Africa suffers from decreased rainfall.
Australia and Southeast Asia: Increased rainfall aids in replenishing water reserves but also increases the risk of flooding and cyclones.
WAY FORWARD:
Short-Term Strategies:
Enhanced Monitoring and Predictive Capabilities:
Invest in advanced weather forecasting technologies to accurately predict El Niño and La Niña events.
Refine IMD methodologies using historical data to identify regions most at risk.
Agricultural Resilience:
Expand crop insurance to cover losses from abnormal weather, providing financial security for farmers.
Offer consultancy on adaptive farming techniques and alternative crops less affected by climate extremes.
Resource Management:
Develop contingency plans for effective water management and storage.
Strengthen public distribution systems to maintain food security during adverse weather.
Financial Support and Policy Interventions:
Ensure flexible credit solutions for farmers impacted by erratic weather.
Facilitate rapid aid and resource disbursement to affected regions.
Long-Term Strategies:
Research and Technological Advancements:
Promote research on climate-resilient agricultural practices and drought-resistant crops.
Support studies to understand the dynamics of ENSO events and global climate interactions.
Infrastructure Development:
Invest in robust infrastructure to withstand extreme weather conditions.
Upgrade rural infrastructure to improve responses to climatic events and reduce economic losses.
Community-Based Approaches:
Strengthen community watershed management and local mitigation strategies.
Encourage community participation in adaptation strategy planning and implementation.
Policy and Governance:
Integrate climate change adaptation into national development planning.
Enhance inter-agency coordination for a unified response to climate-related disasters.
PRACTICE QUESTION:
Q. Describe the mechanisms of El Niño and La Niña and assess their comprehensive impacts on India. (15 marks, 250 words)
