La Niña affects India’s climate
Context
India is set to experience a variety of weather patterns due to the delay in La Niña and is also likely to influence global weather patterns alongside influencing winters and monsoons in India.
Relevance:
GS-01 (Physical Geography)
Dimensions of the Article
- El Nino and Its Impact on Indian Monsoon
- About La Niña
- Impact of La Niña on India
- Significance to India
El Nino and Its Impact on Indian Monsoon:
- Overview of El Nino and La Nina: El Nino and La Nina events are inherent components of the global climate system, influencing weather patterns worldwide.
- El Nino is characterised by warming in the central and eastern tropical Pacific, whereas La Nina entails sustained cooling in the same regions.
- These phenomena operate within the El Nino-Southern Oscillation (ENSO) cycle.
- El Nino’s Mechanism and Consequences: El Nino transpires when trade winds weaken or reverse, allowing warm water from the western Pacific to flow eastward, displacing cooler water in the eastern Pacific.
- This disrupts atmospheric conditions, leading to varied global weather impacts. Effects include heightened rainfall in the southern US and Peru, alongside droughts and bushfires in the West Pacific and Australia.
- El Nino’s Influence on Indian Monsoon: El Nino significantly influences the Indian monsoon through atmospheric circulation.
- The weakened southwest monsoon results in below-normal rainfall, while the northeast monsoon experiences above-normal rainfall during El Nino.
- The extreme 2015 El Nino, for instance, played a crucial role in Chennai’s heavy rainfall.
- Correlation with Bay of Bengal Warming: A correlation emerges with the consistent warming of the Bay of Bengal off the Tamil Nadu and Andhra Pradesh coasts.
- Researchers highlight a positive and significant correlation between Bay of Bengal sea surface temperature and northeast monsoon rainfall.
- The magnitudes of correlations with El Nino conditions and Bay of Bengal warming are remarkably similar, emphasizing their collective impact on weather patterns.
About La Niña
- What is La Niña?
- La Niña is the colder phase of the El Niño Southern Oscillation (ENSO). It is also called the Little Girl in Spanish.
- It is a period that represents below-average sea surface temperature (-0.5ºC or lower) across the east-central Equatorial Pacific.
- On the other hand, El Niño involves warming of the same region, causing contrasting weather patterns globally.
- Key Features of La Niña
- La Niña typically leads to normal or above-normal rainfall during India’s monsoon season.
- Globally, it causes droughts in Africa and intensifies hurricanes in the Atlantic Ocean.
- La Niña winters are marked by colder nights but slightly higher daytime temperatures.
- Current Status
- The Oceanic Niño Index (ONI), a measure of ENSO phases, currently stands at -0.3ºC, which is below the La Niña threshold of -0.5ºC.
- For La Niña to be officially declared, ONI values must remain below -0.5ºC for at least five consecutive readings.
Impact of La Niña on India
Winter Weather Patterns
- Its affects on the Indian subcontinent are varied.
- Part of North India is currently experiencing a delayed winter with above-normal temperatures this year.
- Likewise, contrastingly, southern cities like Bengaluru and Hyderabad are witnessing colder-than-usual winters.
- Typically, La Niña winters cause colder temperatures in north India, but its delay explains the mild winter so far.
Effect on Air Quality
- During La Niña winters:
- Wind speeds are higher, which helps disperse pollutants and improve air quality.
- However, a lower Planetary Boundary Layer Height (PBLH) traps pollutants close to the surface.
- In north India, colder winters often lead to increased biomass burning for heating, further worsening pollution.
Monsoon and Summer
- La Niña years ensure strong monsoons, leading to normal or above-normal rainfall. For instance, the monsoons in 2020, 2021, and 2022 were robust.
- El Niño years disrupt rainfall, causing droughts as seen in 2023.
- If La Niña sets in and continues into the summer of 2025, it may provide relief from extreme heat waves and ensure a better monsoon season.
Significance to India
- Agriculture: As most of India depends on agriculture, the rain-fed regions are supported by La Niña as it helps crop yields and also boosts the economy and ensures food security.
- Energy: The above normal rainfall ensures hydropower generation, reduces pressure on coal-based power plants and helps India achieve its global targets
- Climate Resilience: Understanding the ENSO cycle helps policymakers prepare for its economic and environmental impacts, such as droughts, floods, and extreme heat.
Way Forward
- Climate Monitoring: Strengthen systems for ENSO monitoring using tools like the Oceanic Niño Index (ONI) to better predict La Niña and El Niño events.
- Accurate forecasts will help farmers, industries, and policymakers make informed decisions.
- Adaptation Measures:
- Prepare for both delayed winters and shifting monsoons by improving water management systems, disaster preparedness, and agricultural strategies.
- Increase awareness in vulnerable areas about pollution control during colder winters.
- Climate change mitigation:
- Rising sea temperatures may amplify extreme ENSO events. India must focus on reducing emissions and building resilience to cope with unpredictable weather patterns.
