Understanding EL NINO AND LA NINA Phenomena and Their Implication on India
- June 26, 2014
- Posted by: INSIGHTS
- Category: Inside India
EL NINO and LA NINA
Monsoon is a familiar though a little known climatic phenomenon. In India, from agriculture to economic policies to disaster management, a lot depends on the Monsoon.
The Monsoon is a recurring event i.e. it repeats after a certain frequency of time – a year in our case. But, it may not be uniform in every period (year). There are a lot of factors which affect its duration and intensity over India.
The Monsoon is basically a result of the flow of moisture laden winds because of the variation of temperature across the Indian Ocean.
There are a number of climatic phenomena which affect it namely the Indian ocean dipole, El nino, La nina, Equatorial Indian Ocean Oscillation (EQUINOO) etc. These phenomena affect the temperature distribution over the oceans and thus affecting the direction and intensity of flow of the moisture laden winds.
There have been recent reports that El Nino may disturb the Indian Monsoon and play badly with Indian agriculture. This brings us to the discussion of the concepts of El Nino and La Nina. In what follows we will look at their origin, mechanism, impact and mitigation strategies. We need not go into trivial details but only understand them from exam point of view.
El Nino and La Nina are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle. The ENSO cycle is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the east-central
Equatorial Pacific. (The area between South America and Australia near the equator – look at the diagram)
La Nina is sometimes referred to as the cold phase of ENSO and El Nino as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate, including India.
NOW, it is important to understand how these phenomena affect the Monsoon system? To know this, we must first know the pressure and temperature distribution in the region before their onset. (We are assuming here that you are a little bit familiar with the phenomenon of Monsoon.)
For a normal monsoon season, the pressure distribution is as such:
- The Peruvian coast has relatively high pressure than the areas near north Australia and South-East Asia.
- The Indian Ocean is slightly warmer than the adjoining oceans (West pacific –see diagram) and thus the pressure is low relatively due to the warm seas. This is why the moisture laden winds move from near the west pacific to the Indian Ocean and from there on to the lands.
- The pressure on heated Indian land is much lower than that on the Indian Ocean.
This facilitates the movement of monsoon winds from the sea to the Indian land without any significant diversion.
But if for some reason this normal distribution is affected, then there is a change in the way trade winds (or monsoon winds) would blow.
However, the following is the pressure and temperature distribution in an El-Nino situation.
This is because of the following reasons (and its effects):
Off the coast of Peru (read in Eastern Pacific and Central Pacific), there is normally cool surface water because of the cold Peruvian current. But El Niño makes it go warm.
When the water becomes warm, the tread winds, which otherwise flow from East to west, either reverse their direction or get lost.
Due to this warm water, the air gets up and surface air pressure above Eastern Pacific gets down. On the other hand, the waters cool off in western pacific and off Asia. This leads to rise in surface pressure over the Indian Ocean, Indonesia, and Australia.
Now as the pressure over the Peruvian coast reduces because of the warm sea water, the flow of moisture laden winds is directed to the Peruvian coasts from the western pacific (the areas near North Australia and South-east Asia – refer to the diagrams above).
Hence, the moisture laden winds that should have moved towards the Indian coast now move towards the Peruvian coast.
The warm water causes lots of clouds getting formed in that area, causing heavy rains in Peruvian desert during El Niño years.
This robs the Indian subcontinent of its share in the Monsoon rains. The greater the temperature and pressure difference, the greater would be the shortage in the rainfall in India.
La Niña, “anti-El Niño” or simply “a cold event” is the cooling of water in the Eastern Pacific Ocean.
The following happens in La-Nina:
The water in Eastern Pacific, which is otherwise cool; gets colder than normal. There is no reversal of the trade winds but it causes strong high pressure over the eastern equatorial Pacific.
On the other hand, low pressure is caused over Western Pacific and Off Asia.
This has so far caused the following major effects: Drought in Ecuador and Peru. Low temperature, High Pressure in Eastern Pacific.
Heavy floods in Australia; High Temperature in Western Pacific, Indian Ocean, Off coast Somalia and good rains in India. Drought in East Africa.
For India, an El Niño is often a cause for concern because of its adverse impact on the south-west monsoon; this happened in 2009. A La Niña, on the other hand, is often beneficial for the monsoon, especially in the latter half. The La Niña that appeared in the Pacific in 2010 probably helped 2010’s south-west monsoon end on a favorable note. However, it also contributed to the deluge in Australia, which resulted in one of that country’s worst natural disasters with large parts of Queensland either under water from floods of unusual proportions or being battered by tropical cyclones.
This distortion is pressure and temperature recurs every 4-5 years. But it may not happen exactly after 4-5 years or it may not happen at all. It periodicity is thus quite uncertain.
El Nino and La Nina episodes typically last nine to 12 months, but some prolonged events may last for years. They often begin to form between June and August, reach peak strength between December and April, and then decay between May and July of the following year. While their periodicity can be quite irregular, El Nino and La Nina events occur about every three to five years. Typically, El Nino occurs more frequently than La Nina.
Correlation of El-Nino, La- Nina and drought in the Indian Landscape
“Looking at the relation between El Nino and Indian droughts since 1950, it is observed that India faced 13 droughts and 10 of these were in El Nino years and one in a La Nina year. This indicates there may not be a one-to-one correspondence between El Nino and Indian droughts,” the paper by Ashok Gulati and Shweta Saini of Indian Council for Research on International Economic Relations (ICRIER) has stated.
“Overall, the analysis proves that since the 1980s, only El Nino years converted into droughts for our country. However, a La Nina year does not guarantee better-than-normal rains and similarly
an El Nino year does not always translate into below-normal rains,” it said.
The paper also stated that as El Nino phenomenon may hit in the second half of the monsoon season in 2014, factors such as favourable water reservoir levels, and high stocks of grains with the government may offer relief to farmers and consumers.
Impact of El-Nino
- Normal or High rainfall in Eastern/Central Pacific
- Drought or scant rainfall in western pacific/Asia
This leads to a lot of undesirable circumstances.
“When the rainfall for the monsoon season of June to September for the country as a whole is within 10% of its long period average, it is categorised as a normal monsoon. When the monsoon rainfall deficiency exceeds 10%, it is categorised as an all-India drought year.” – IMD
In India, almost 50% of the area under cultivation is rain-fed. Indian agriculture is thus heavily dependent on the climate of India: a favorable southwest summer monsoon is critical in securing water for irrigating Indian crops. So, a significant reduction in total rain fall results in a drought like situation.
Drought in India has resulted in tens of millions of deaths over the course of the 18th, 19th, and 20th centuries.
In some parts of India, the failure of the monsoons result in water shortages, resulting in below-average crop yields.
This is particularly true of major drought-prone regions such as southern and eastern Maharashtra, northern Karnataka, Andhra Pradesh, Odisha, Gujarat, and Rajasthan.
A lot of Farmers suicide because they are not be able to repay the loan they had taken for growing the crop.
Shortages in food supply then result in spike in food prices all across the country pushing inflation up. High food inflation eats into other sectors too such as food processing sector.
This pushes the RBI and the government to adopt a more cautious approach to monetary and fiscal policy respectively.
A tighter monetary policy to tame food inflation may affect the economic growth rate of the nation. Besides, lower agricultural production already lower the GDP of the nation dealing a double blow.
- If the drought is severe, it would dry up major sources of fresh water leading to a water crisis like situation. The ground water level will also go down. This would not only affect supply of drinking water, but also supplies of water into canals and hand-pumps for agricultural irrigation.
- Weak monsoons also result in lesser power generation from hydro power dams thus leading to even lesser electricity for irrigation purposes. This further reduces the crop yield.
- Another important source of income for the farmers is livestock and the fisheries. Both are affected severely by the drought.
What is the WAY OUT?
The government must expand the farm insurance cover and advice banks and financial institutions to settle crop insurance claims in the drought-hit areas without delay. Otherwise, we will be seeing a lot of farmer suicides.
High quality seeds of alternative crops must be distributed among farmers in the drought-affected areas.
The government must realistically assess the ground level situation in order to estimate the shortfall of oilseeds and pulses and help traders with market intelligence.
It should also bring down the cereals’ inflation by liquidating the extra stock it was holding, which is way above the buffer requirement.
Scrapping the APMC Act and allowing free flow of agriculture goods among the states. This would help bridge the mismatch of demand and supply of goods, which is the underlying factor contributing inflation.
The distribution of pulses through public channels at subsidised prices as was done in 2008 to all the households is needed.
The government should also provide the fuel subsidy that enables farmers to provide supplementary/alternative irrigation through pump sets in the drought and deficient rainfall areas to protect the standing crops.
Developing drought free crop varieties and distributing its subsidized seeds to the farmers. It is a part of National Action plan on climate change in Agriculture.
Strengthening the crop insurance regime in India by making the drought identification, drought and crop loss claim and receipt of relief efficient, quick and transparent.
Achieving financial inclusion so that the farmers are able to take loans from more credible, accommodative and benevolent sources such as regional rural banks (RRBs). This would help them tackle distress like situations.
Using low water use technologies like drip and sprinkler irrigation.
Moving away from water intensive crops to less water consuming crops. The MSP regime in India has to provide more remuneration for other less water consuming crops. As in India, about 80% of the water is used for agricultural purposes, a lot of which is used by crops such as rice.
Strengthening community watershed management and development. This can be done by protecting and conserving local water sources like ponds, lakes etc. Several government schemes like MGNREGA, Integrated watershed Development Programme etc. can be utilized in this.
- Developing early warning systems and alerting the farmers much in advance like in the recently launched Kissan SMS scheme.
Model questions for Prelims and Mains
1. Consider the following statements:
1. El-nino is caused due to the occurrence of a warm current off the coast of Peru.
2. La-Nina is caused due to the occurrence of a cold current off the coast of Australia.
Which of these is/are true?
a) Only 1
b) Only 2
d) None of the above
2. Which of the following sectors can possibly be affected by the onset of El-nino?
1. Food processing industries
2. Irrigation sector
3. Power sector
Choose the correct answer using the codes below:
a) 1 and 2
b) 2 and 3
c) 1 and 3
d) All of the above
3. Consider the following statements:
1. El-nino and La-nina are regular climatic events.
2. La-Nina generally adversely affects the Indian monsson.
3. The event El-nino can change the normal direction of the trade winds in Central pacific ocean.
Which of these is/are true?
a) 1 and 2
b) 2 and 3
c) 1 and 3
d) All of the above
1. Discuss the mechanism of El-nino and establish its effect on the Indian agriculture in general. (200 words)
2. In view of El-Nino, what immediate and long term steps can be taken by government at the state and local levels? (200 words)
3. “Better management of the Public Distribution System (PDS) can mitigate the impact of El-Nino on the Indian economy.” Elucidate. (200 words)