La Nina (‘Little Girl‘ in Spanish) is a natural and periodic weather pattern that occurs due to fluctuating ocean temperatures in one particular part of the world, namely the east-central equatorial Pacific Ocean. It is the cyclic process of cooling sea surface temperature in the central and eastern Pacific Oceans situated in the equatorial region. This cooling effect results in unique patterns of tropical wind circulation, atmospheric pressure, and rainfall, causing significant changes in weather and climate. The unusual cooling of seawater causes less water evaporation so the air above becomes dryer, cooler, and denser.
This dense air doesn’t develop into storms and causes less rainfall in certain parts of the world and more rainfall in other parts. This natural event typically occurs in a cycle of five to seven years and lasts for about three years. That is why it is called triple-dip La Nina. La Nina gives rise to stronger ocean winds that intensify during July and August, affecting temperature and rainfall patterns. This leads to storms, drought, and flood-like situations.
‘Triple-Dip’ La Nina:
The World Meteorological Organization (WMO) has extensively studied the nature of La Nina and has made the forecast that La Nina will occur in three consecutive northern hemisphere winters. This is termed the ‘triple-dip’ effects of La Nina. Scientists of WMO had predicted for quite some time that La Nina is underway, and the condition has strengthened between July and August and is likely to intensify further. This change in weather patterns would be observed in floods, droughts, and tropical cyclones worldwide.
As per the latest update of WMO released on August 31, 2022, the oceanic and atmospheric phenomenon would last until at least the end of the year and for the first time this century, span three consecutive northern hemisphere winters to become a ‘triple dip’ La Nina. The National Oceanic and Atmospheric Administration (NOAA) has made a forecast that the La Nina winter season is expected to continue from December 2022 to February 2023.
The Impact of Triple Dip La Nina:
- La Nina is a natural geographical phenomenon that can have a significant global impact because of its effect on weather and climate. It is exceptional to have three consecutive years of La Nina events, known as triple-deep La Nina. This event will have some effect by slowing down the rise in global temperatures, but scientists conclude that it will not stop or reverse the long-term warming trend of the earth.
- During a La Nina, the sea surface temperatures over the central and eastern Pacific oceans become cooler than normal. The sea winds blow towards the warm areas with high force causing storms. The change in weather caused by the triple dip La Nina has led to droughts in North and South America, equatorial eastern Africa, and floods in Asia. The WMO predicted that the triple dip La Nina, which began in September 2020, would continue till September-November 2022 and then up to February 2023, making it a three-year-long phenomenon.
- The La Nina event will cause more rainfall over some regions of Southeast Asia, especially Indonesia and Australia, but will reduce rainfall in other areas, such as Africa and the western United States. Triple-dip La Nina will generate stronger ocean winds that intensify during July and August, affecting temperature and rainfall patterns.
- The overall global impact will be manifested in the form of droughts in Ecuador and Peru, heavy floods in Australia, high temperatures in the western pacific, and good rains in India. In the US, the winter temperature tends to be cooler than average in the Northwest and warmer than average in the Southeast. This means The USA experiences warmer, drier weather across the Southeast and cooler, wetter conditions in the Northwest.
Features of Triple dip La Nina:
Triple dip La Nina is a part of the global climatic cycle that occurs when the temperature above the Pacific Ocean changes, leading to unusual wind patterns, ocean currents, and climatic behavior. Various features of triple dip La Nina are identified by scientists that contribute to the largest natural effects on climate, which are mentioned as follows:
- The Sea Surface temperature originates when cooler than usual ocean temperatures occur in the equatorial regions. La Nina causes a decrease in sea-surface temperature by more than 0.5 degrees Celsius for at least five successive three-month seasons.
- Pressure: It contains low air surface pressure in the eastern Pacific areas.
- Trade winds: It makes the trade winds blow with more pressure and force.
- Seasons: The northwest of the pacific observes above-average precipitation in winter seasons and the southwest of the pacific experiences a dry climate and below-average rainfall.
- Ocean waters in the Pacific: Cold water causes reduced precipitation, increasing drought occurrence in certain parts.
- Cyclones: It increases the chances of intense tropical cyclones as wind direction changes rapidly.
La Nina and El Nino:
As the ocean surface temperature changes in response to atmospheric conditions, it modifies the weather patterns periodically. El Nino (the warm phase) and La Nina (the cold phase) are two different phases. These extreme phases are called the El Nino-Southern Oscillation (ENSO) cycle. La Nina usually occurs after El Nino, which warms the surface of the eastern tropical Pacific Ocean.
El Nino is related to the warming of the central and eastern parts of the Pacific Ocean, while La Nina causes the reverse effects with a sustained cooling of the sea surface in these areas. El Nino contributes to more eastern and central Pacific hurricanes, while La Nina causes fewer hurricanes in Atlantic regions.
Effect of Triple Dip La Nina on The Indian Subcontinent:
- Triple dip La Nina continues for a period that extends up to three consecutive winters. Such an extension would result in more variation in the temperatures in the world and an increase in the frequency of rain, floods, and droughts in different parts of the world. The triple dip La Nina causes extended southwest monsoon season in South Asia, including India, which means excessive rainfall and subsequent floods.
- In 2021, the triple dip La Nina was one of the factors that caused extraordinary rainfall during the post-monsoon season in the southern part of India. In 2022 also, an active monsoon season caused floods in many Indian states, such as northeastern states and eastern states in India.
- It is predicted that the monsoon season will be extended in the Indian subcontinent, especially in Gujarat, Rajasthan, Maharashtra, Orissa, Karnataka, and Uttar Pradesh, due to the effect of the triple dip La Nina. The warming of sea surfaces leads to the continuous formation of low-pressure areas and depressions, causing more rainfall and fresh floods in the coming months against an active triple dip La Nina.
Important data on Triple Dip La Nina:
- The longest triple dip La Nina continued for 30 months from the spring of 1973 to the spring of 1976, as per the National Oceanic and Atmospheric Administration (NOAA) record.
- The National Oceanic and Atmospheric Administration (NOAA) forecasts that the expected winter season of triple dip La Nina will happen between December 2022 and February 2023.
- The first triple-dip La Nina of the 21st century, which started in September 2020, is the third since 1950. The present phase of La Nina is going to be the first ‘triple dip’ event of the 21st century.
- The WMO predicts that the current triple dip La Nina will continue and will intensify by 70% in September-November 2022 but gradually decrease to 55% in December-February 2022/2023.
Conclusion:
Triple dip La Nina is a part of a cyclic geographical phenomenon that generally continues for three consecutive winter seasons and can significantly impact global weather, climate, and ocean conditions. It also affects food production, human health, and water supply due to abnormal changes in weather conditions. In today’s world, all unusual and extreme climate events have some connection with human-induced environmental pollution, which must be controlled by any means.