No El Nino expected, it will be a ‘normal’ monsoon, says Skymet
GS 1, Geography.
Context:
- El Nino, which is characterised by a warming of temperatures in the Central Pacific and is connected with low rainfall over India, is not likely to appear this year.
- Its polar opposite, or La Nina, contributed to two years of above-average rainfall in 2019 and 2020, as well as “normal” rainfall in 2021.
- The previous two monsoon seasons have been driven by the southwest monsoon, and rainfall in August, the second rainiest month, is projected to be muted in 2022.
- The north-eastern states have a high baseline amount of precipitation. However, the major kharif agricultural districts of Punjab, Haryana, and Uttar Pradesh, as well as the rain-fed provinces of Maharashtra and Madhya Pradesh, have seen back-to-back La Nina episodes… the development of El Nino, which generally corrupts the monsoon, is ruled out.
About El Nino:
- El Nino is a climatic trend characterised by unusually warm surface waters in the eastern tropical Pacific Ocean.
- El Nino is the “warm phase” of the El Nino-Southern Oscillation, which is a broader phenomenon (ENSO).
- El Nino and La Nia are the ocean components of ENSO, whereas the Southern Oscillation is the atmospheric component.
- El Nino affects ocean temperatures, ocean current speed and intensity, coastal fisheries health, and local weather from Australia to South America and beyond.
- El Nino episodes occur at sporadic intervals of two to seven years. El Nino, on the other hand, is not a regular cycle or predictable in the same way that ocean tides are.
- Because of the Pacific basin’s breadth (it covers one-third of the earth), fluctuations in wind and humidity are carried throughout the world, affecting circulation patterns such as jet streams (strong upper-level winds).
Impacts on global climate:
- Tropical cyclones- During El Nino and La Nina occurrences, equatorial heating anomalies cause abnormal tropical and extratropical atmospheric wave trains, altering circulation, vertical shear, and steering flow. During El Nino (La Nina) episodes, shear shifts lead tropical cyclones to develop further south and east (north and west) than usual.
- Asia’s regional consequences- Warm water moves from the west Pacific and Indian Ocean to the east Pacific, bringing rain with it, producing widespread dryness in the western Pacific and rainfall in the generally dry eastern Pacific.
- Economic Implications- Extensive Ocean warming and a decrease in easterly trade winds impede upwelling of cold nutrient-rich deep water, which can have major economic consequences for local fishing for an international market.
El Nino, in general, can have an impact on commodities prices and the macroeconomics of many nations.
It has the potential to limit the availability of rain-driven agricultural commodities, diminish agricultural production, construction, and service activities, cause food-price and generalised inflation, and cause social unrest in commodity-dependent impoverished nations that rely mostly on imported food.
- Health and social consequences- Extreme weather events associated with the El Nino cycle are associated with fluctuations in the occurrence of pandemic illnesses. For example, the El Nino cycle has been linked to elevated risks of mosquito-borne illnesses such as malaria, dengue fever, and Rift Valley fever.
El Nino has now been connected to malaria cycles in India, Venezuela, Brazil, and Colombia. Outbreaks of another mosquito-borne illness, Australian encephalitis (Murray Valley encephalitis—MVE), occur in temperate south-east Australia following significant rainfall and floods caused by La Nina episodes. ENSO conditions have also been linked to the occurrence of Kawasaki illness in Japan and along the west coast of the United States, owing to the relationship to tropospheric winds over the north Pacific Ocean.
- Environmental ramifications- Insect populations declined with El Nino 2015–16’s catastrophic drought and devastating fires. In Amazonian burnt forests, declines in habitat-specialist and disturbance-sensitive bird species, as well as large-frugivorous animals, were also noted. Most notably, worldwide mass bleaching episodes occurred in 1997–98 and 2015–16, resulting in 75–99 percent losses of living coral throughout the world.
About La Nina:
- La Nina is distinguished by exceptionally cold Equatorial Pacific water temperatures, as opposed to El Nino, which is distinguished by abnormally warm Equatorial Pacific Ocean temperatures.
- La Nina, like El Nino, is a weather trend that occurs every few years in the Pacific Ocean. Winds around the equator drive warm water westward in a typical year. Warm water at the ocean’s surface blows from South America to Indonesia. Cold water from the deep comes to the surface while warm water travels west.
- This frigid water eventually reaches the shore of South America. These winds are substantially stronger than typical during the winter of a La Nina year. As a result, the water in the Pacific Ocean near the equator is a few degrees cooler than typical. Even a little shift in ocean temperature may have a global impact on weather.
- It is created by a collision between the Pacific Ocean and the upper atmosphere. However, it has the potential to affect weather patterns all across the planet. Furthermore, the climatic circumstances during La Nina can contribute to the formation of additional tropical cyclones, including hurricanes, in the deep tropics (near the islands in the Caribbean, for example).
- Implications on Asia- During La Nina years, the development of tropical cyclones, as well as the position of the subtropical ridge, shifts westward over the western Pacific Ocean, increasing the risk of landfall in China.
-La Nina caused a 2°C (3.6°F) dip in sea surface temperatures over Southeast Asia in March 2008. It also brought severe rain to Malaysia, the Philippines, and Indonesia.
- Weather Conditions- La Nina is also distinguished by above-normal pressure throughout the central and eastern Pacific. As a result, cloud formation and rainfall in that area are reduced. Drier-than-normal conditions have been reported along tropical South America’s west coast, the Gulf Coast of the United States, and the pampas area of southern South America.
- Economic Viability- La Nina is often beneficial to the fishing sector in western South America. Cold, nutrient-rich waters rise to the top as a result of upwelling.
- Marine Life- Plankton, which is consumed by fish and crabs, contains nutrients. Crustaceans are preyed upon by higher-level predators such as high-value fish species such as sea bass.
La Nina events can continue anywhere from one to three years, as opposed to El Nino, which normally lasts little more than a year. Both phenomena tend to peak during the winter months in the Northern Hemisphere.
