La Niña – Impacts and Predictions for 2024

La Niña is climate phenomenon that influences global weather patterns. It is a phase of the El Niño Southern Oscillation (ENSO) characterised by cooler sea surface temperatures in the central and eastern Pacific Ocean. The effects of La Niña are felt worldwide, impacting rainfall, temperatures, and storm activity.

About La Niña and El Niño

La Niña and its counterpart, El Niño, are critical to understanding climate variability. La Niña typically brings increased rainfall to India during the monsoon season. Conversely, El Niño often results in droughts and extreme heat in the same region. The interplay between these phases shapes weather patterns globally, affecting agriculture, water supply, and disaster preparedness.

Current Status and Predictions

As of late 2024, the emergence of La Niña is uncertain. The India Meteorological Department predicts a possible onset by late 2024 or early 2025. The current oceanic Niño index (ONI) indicates a temperature of around -0.3ºC, suggesting that La Niña has not yet developed. Historically, La Niña typically forms during the monsoon or pre-monsoon periods, making the current situation unusual.

Impact on Weather Patterns

The effects of La Niña extend beyond India. It is known to cause droughts in parts of Africa and intensify hurricanes in the Atlantic. In India, La Niña years have been associated with normal or above-normal rainfall, which contrasts sharply with the dry conditions during El Niño years. The potential for a La Niña event may bring relief from extreme heat and improve rainfall distribution.

Climate Change and La Niña

Climate change is expected to increase the frequency and intensity of both La Niña and El Niño events. Rising global temperatures can disrupt the delicate balance of oceanic and atmospheric conditions that govern these phenomena. This may lead to more extreme weather patterns, including harsher winters and more intense heat waves.

Meteorological Analysis

Research indicates that La Niña winters feature colder nights but higher daytime temperatures compared to El Niño. Wind speeds tend to be higher during La Niña, which can improve air quality by dispersing pollutants. However, if La Niña sets in, it may also lead to increased biomass burning for heating, potentially worsening air quality.

Historical Context and Future Implications

The decade began with a rare occurrence of three consecutive La Niña events, known as a Triple Dip La Niña. Following this, an El Niño phase was observed in 2023. The implications of these shifts are for agriculture and water management in India. If La Niña develops and persists into the summer of 2025, it could mitigate the impacts of extreme heat and enhance monsoon rainfall.

Questions for UPSC:

1. Examine the relationship between La Niña and global weather patterns.
2. Critically discuss the potential impacts of climate change on La Niña events.
3. Analyse the historical patterns of rainfall during La Niña and El Niño years in India.
4. Point out the meteorological indicators that signify the onset of La Niña or El Niño.

Answer Hints:

1. Examine the relationship between La Niña and global weather patterns.

1. La Niña causes cooler sea surface temperatures in the Pacific, affecting atmospheric circulation.
2. It typically results in increased rainfall in India during the monsoon season.
3. Conversely, it leads to droughts in Africa and intensifies hurricanes in the Atlantic.
4. El Niño, its counterpart, brings extreme heat and drought in India, showcasing their contrasting effects.
5. The interplay between La Niña and El Niño shapes global agricultural productivity and disaster preparedness.

2. Critically discuss the potential impacts of climate change on La Niña events.

1. Climate change may increase the frequency and intensity of both La Niña and El Niño events.
2. Rising global temperatures disrupt oceanic and atmospheric balances crucial for ENSO phenomena.
3. Extreme La Niña events could lead to harsher winters and more intense heatwaves in affected regions.
4. Changes in sea surface temperatures may alter traditional weather patterns associated with La Niña.
5. Increased variability in weather may challenge agricultural practices and water resource management.

3. Analyse the historical patterns of rainfall during La Niña and El Niño years in India.

1. La Niña years (e.g., 2020-2022) typically see normal or above-normal rainfall during monsoons.
2. El Niño years often result in below-average rainfall, affecting agricultural productivity.
3. Since 1871, at least half of the El Niño years have led to drought conditions in India.
4. Historical data shows evolving rainfall patterns, with central India less affected by intense El Niño.
5. A potential La Niña in 2024 could mitigate extreme heat and enhance monsoon rainfall in 2025.

4. Point out the meteorological indicators that signify the onset of La Niña or El Niño.

1. The Oceanic Niño Index (ONI) is a key indicator, comparing sea surface temperatures to a 30-year average.
2. An ONI value of -0.5ºC or lower indicates La Niña, while 0.5ºC or higher indicates El Niño.
3. For a full-fledged event, ONI values must exceed the thresholds five times consecutively.
4. Current ONI values around -0.3ºC suggest La Niña has not yet developed as of late 2024.
5. Historical formation patterns indicate La Niña typically occurs during monsoon or pre-monsoon periods.