 "La Niña, which literally translates to 'little girl' in Spanish, is a climate pattern characterised by the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific Ocean. PTI")
Meteorologists are closely monitoring La Nina weather phenomenon, which is expected to play a significant role in shaping the second half of monsoons in India.
The Indian Meteorological Department (IMD) said rainfall in the months of August-September is most likely to be ‘above normal’ in the country as La Niña has the potential to amplify rainfall across various regions, heightening the risk of landslides and urban floods.
“We are moving towards a La Nina weather condition and its impact is becoming visible,” Mrutyunjay Mohapatra, director-general of IMD said at a press conference adding that “La Nina will play a role in increased rainfall activity in September.”
Understanding the dynamics of La Niña and its potential impact on weather patterns is crucial. Let’s take a closer look
What is La Nina?
La Niña, which literally translates to “little girl” in Spanish, is a climate pattern characterised by the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific Ocean.
Earth’s west-east rotation causes all winds blowing between 30 degrees to the north and south of the equator to have a 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.
The Earth’s west to east rotation causes winds blowing between 30 degrees north and south of the equator to slant in their trajectory, causing winds in the region flow towards a northwesterly direction in the southern hemisphere and a southwesterly direction in the northern hemisphere, causing what is known as the Coriolis Effect.
Impact Shorts
More ShortsThis results in winds in this belt (trade winds) blowing westward along the equator, to move from South America towards Asia. This wind movement causes upwelling, where cold water below the ocean surface rises to replace the warm surface waters.
During a La Niña event, strong trade winds push warm water towards Asia, increasing upwelling and bringing cold, nutrient-rich water to the surface near South America.
In contrast, El Niño, meaning “little boy” in Spanish, occurs when weak trade winds allow warm water to remain in the central and eastern Pacific, preventing upwelling and leading to warmer-than-usual sea surface temperatures.
La Niña events occur periodically every few years, lasting from several months to up to two years. They impact global weather patterns, typically resulting in above-average rainfall in some regions and droughts in others.
What do IMD prediction say?
According to the Meteorological Department, India experienced higher-than-normal rainfall in several regions in July 2024, which is beneficial for agricultural activities. However, for the second half of the monsoon season, rainfall is predicted to exceed 106 percent of the average.
Rains triggered by La Niña in September may result in multiple incidents of city flooding, floods in low-lying areas, and landslides in hilly terrains.
Despite the emergence of La Niña, which could continue until February 2025, the IMD noted that some areas, including parts of eastern, northeastern, central, and southern India, might still receive less rainfall than usual, as was the case in eight states in July.
“During the second half of the monsoon season, normal to above-normal rainfall is most likely over most parts of the country, except many parts of northeast and adjoining areas of east India, Ladakh, Saurashtra & Kutch, and some isolated pockets of central and peninsular India where below-normal rainfall is likely,” said IMD chief Mrutyunjay Mohapatra.
The La Nina impact
The Global Report on Internal Displacement 2023 (GRID-2023), published by the Internal Displacement Monitoring Centre, highlighted that weather-related disasters displaced 8.7 million people across 88 countries and territories by December 2022.
The report attributed this surge in disasters to the prolonged three-year La Niña event. “(This is) largely the result of the effects of La Niña which continued for a third consecutive year,” noted the IDMC’s report.
La Niña was also behind the devastating floods in Pakistan in 2022, displacing around 8.16 million people, the highest number of disaster displacements globally. Record levels of flood displacement were seen in countries such as Pakistan, Nigeria, and Brazil, with India ranking fourth.
Additionally, La Niña caused “the worst drought on record" in Somalia, Ethiopia, and Kenya, triggering 2.1 million displacements.
On the western coast, during the 2020–2023 La Niña event, the North Atlantic Ocean experienced record-breaking tropical cyclone activity. Hurricanes Laura, Eta, Iota, Ida, Fiona, and Ian caused hundreds of deaths and billions of dollars in property damage.
With input from agencies