Third La Nina Event
Source: DTE
GS I: World Geography and Indian Geography
What is discussed under the Third La Nina Event?
- What Is La Nina and El Nino?
- Rare ‘triple’ La Niña Climate Event
- Impacts of Third Consecutive La Nina in India
Why in News?
- According to a forecast made by Australia’s Bureau of Meteorology (BOM) on August 25, 2022, a third consecutive La Nina event may be in the process, which would increase rainfall along the country’s east coast this summer.
- The BOM predicted a 70% chance of the La Nina event.
- The US and UK weather services, however, say that the phenomenon has already begun.
What Is La Nina and El Nino?
- La Niña and El Niño are climate patterns in the Pacific Ocean that can affect weather worldwide.
- Trade winds blow west along the equator in the Pacific Ocean under normal conditions, carrying warm water from South America towards Asia.
Image by 0fjd125gk87 from Pixabay - Upwelling is the process by which cold water rises from the depths to replace that warm water.
- These normal circumstances are disrupted by the opposing climatic patterns El Nino and La Nina.
- The El Nino-Southern Oscillation (ENSO) cycle is the name given to these events by scientists.
- Both El Nino and La Nina have the potential to affect weather, wildfires, ecosystems, and economies on a worldwide scale.
- El Nino and La Nina episodes normally last between nine and twelve months, although can may persist for years.
- In general, El Nino and La Nina occurrences happen every two to seven years, although they don’t always happen at the same time.
- El Nino often happens more frequently than La Nina.
What Is El Nino?
- El Niño means Little Boy, or Christ Child in Spanish.
- El Nino de Navidad was the full term they used because it usually peaks in December.
- During El Niño, trade winds weaken.
- Warm water is pushed back east, toward the west coast of the Americas.
- In the 1600s, South American fishermen noticed areas of unusually warm Pacific Ocean water.
Impacts on whether
- El Nino has a big impact on the weather.
- The Pacific jet stream moves south of its neutral location due to the warmer seas.
- The northern U.S. and Canada are experiencing drier and warmer weather than typical as a result of this change.
- However, these periods are wetter than usual and have more flooding in the Southeast and Gulf Coast regions of the United States.
Impacts on marine life
- El Nino has a significant impact on marine biodiversity off the Pacific coast as well.
- Under normal circumstances, upwelling delivers cold, nutrient-rich water from the depths to the top.
- Upwelling weakens or ceases entirely during El Nino.
- There is fewer phytoplankton off the shore when the nutrients from the deep are lacking.
- This has an impact on fish that consume phytoplankton, which has an impact on everything that consumes fish.
- Additionally, tropical species like yellowtail and albacore tuna may enter regions that are often too cold due to the warmer seas.
What Is La Niña?
- La Nina is Spanish for ‘Little Girl’.
- La Nina is also frequently referred to as El Viejo, the opposite of El Nino, or just ‘a cold event’.
- La Niña has the opposite effect of El Niño .
- Trade winds are much stronger than usual during La Nina occurrences, bringing more warm water into Asia.
- Upwelling increases off the west coast of the Americas, sending cold, nutrient-rich water to the surface.
Impacts on whether
- The Pacific’s cold waters push the jet stream northward.
- Drought in the southern United States and severe rainfall and flooding in the Pacific Northwest and Canada are often the results of this.
- Wintertime temperatures are often warmer in the South and colder in the North during a La Nina year.
- Another effect of La Nina is a more intense storm season.
Impacts on marine life
- The waters off the Pacific coast are colder and richer in nutrients during La Nina.
- Because of this environment, areas like the California coast are home to more marine life and cold-water animals like squid and salmon.
Rare ‘triple’ La Niña Climate Event
- According to the most recent predictions, a prolonged La Nina event that has aggravated droughts in the US and East Africa and caused flooding in eastern Australia may continue into 2023.
- In the Northern Hemisphere, two consecutive La Nina winters are common, but three consecutive ones are exceedingly uncommon.
- Only twice since 1950 has there been a “triple dip” La Nina, which lasts for three years straight.
- According to experts, this abnormally prolonged La Nina is probably simply a random blip in the climate.
- However, other researchers are cautioning that climate change may increase the likelihood of future La Nina-like situations.
- More instances of La Nina would increase the likelihood of floods in Southeast Asia, raise the danger of droughts and wildfires in the Southwest of the United States.
- Also, it may alter the pattern of storms, cyclones, and monsoons across the Pacific and Atlantic oceans, among other regional effects.
Impacts of Third Consecutive La Nina in India
- Due to La Nina, the monsoon season in India will last till October.
- According to the India Meteorological Department (IMD), although the monsoon retreat may start in the first week of September, some areas of India may still get significant rainfall.
- Even if the monsoon in India was expected to be surplus this year, there are several regions where the rainfall has been below average.
- This is because the monsoon is being impacted by warming in the Pacific and Arctic.
Effect on agriculture
- If it rains at this time, farmers run the danger of losing their standing Kharif crops.
- Beginning at the end of September or early October is the Kharif crop harvesting season.
- Any rainfall before then would be harmful to the crops that are now in place.
- Already, the overall area sown under Kharif this season lags by 2.5 million hectares (mha) as of August 18, 2022, compared to the corresponding period in 2021.
- This is according to data on the website of the Union Ministry of Agriculture and Farmers’ Welfare.
- The area under paddy, the main Kharif crop, is short by 3.09 mha (8.2 per cent less), compared to 2021.
- A lot of farmers also harvest their produce and store it for a few days since the procurement process takes longer than expected.
- Rains at that time would ruin the produce that had been gathered.
What is upwelling?
- Water is pushed away by winds that sweep over the ocean’s surface.
- The water that was pushed away is then replaced by water that comes up from below the surface.
- Upwelling is the term for this procedure.
- Both in the open ocean and along coasts, upwelling takes place.
- When wind-induced surface water buildup along shoreline results in surface water gradually sinking toward the bottom, the opposite process, known as “downwelling,” also takes place.
- As a result of upwelling, nutrient-rich, often cooler water rises to the top. Surface waters are “fertilised” by these nutrients, which means that they frequently have high biological production.
- As a result, good fishing spots are usually found where upwelling is frequent.
What are Kharif crops?
- Kharif crops are often referred to as monsoon crops or autumn crops.
- They are domesticated plants that are grown and harvested in India, Pakistan, and Bangladesh from June to November during the monsoon season in the Indian subcontinent.
- In some areas of the Indian subcontinent, the monsoon season can start as early as May, and crops are typically harvested from the third week of September to the end of October.
- In India, some of the most important Kharif crops include rice, maize, and cotton.
- The Kharif crops require adequate rainfall as opposed to the Rabi crops, which are planted in the winter.
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