What is El Nino, Impact on Indian Summer Monsoon Due to Climate Change

Scientists have cautioned that this year's advancing El Nino weather patterns could result in a deficiency in monsoon rainfall.

What is El Niño and La Niña?

An El Nino condition develops when east winds blow less forcefully than usual and seawater temperatures in the equatorial Pacific Ocean warm up by 0.5°C over the long-term average. The upwelling of cold water from the ocean floor causes water temperatures to drop below average during La Nina. La Nia has the power to change both the direction and the speed of the trade winds, which bring on India's winter. El Nio and La Nina are the polar opposites of the El Nino Southern Oscillation (ENSO). Positive sea surface temperature (SST) anomalies have grown during the past four weeks in the far western and eastern Pacific, particularly close to the coasts of Ecuador and Peru.

At the moment, negative SST anomalies have steadily diminished across most of the equatorial Pacific Ocean. Positive SST indicates that ocean temperatures are higher than average, whilst negative SST suggests that they are lower than average.

Predictions by India Meteorological Department (IMD)

Last week, the India Meteorological Department (IMD) released its primary monsoon forecast. The IMD anticipates that this year's monsoon will bring 96% of the Long Period Average in terms of total rainfall recorded throughout the season (with a modelling error of +/-5%). If the forecast comes true, monsoon performance will fall inside the "normal" range, albeit narrowly. Midway through summer 2023, India is restless despite the usual prediction. Significant changes in oceanic and atmospheric circulations could have profound effects on South Asia.

The Pacific Ocean-based El Nino Southern Oscillation (ENSO), a natural cycle of warming and cooling, is increasingly displaying signals of a phase change. The Pacific is displaying symptoms of warming, pointing to the resumption of the El Nio-the warm phase of the cycle-after a protracted La Nia-the cool phase of the ENSO, which lasted three years. Forecasters from all over the world anticipate that by May 2023, the Northern Hemisphere will have transitioned to an ENSO-neutral state and may subsequently enter an El Nio phase as a result of the equatorial Pacific's sea surface temperatures gradually rising. According to certain estimates, there is a 50% chance that an El Nino will form between July and September 2023.

Predictions by World Meteorological Organization (WMO)

According to the World Meteorological Organization (WMO), the likelihood of an El Nino emerging this year progressively rises from 15% in April to June to 35% in May to July, and then rises to much higher odds of roughly 55% in June to August.

El Nio is also expected to emerge later this year, according to the Department of Meteorology in Australia, which has also issued an El Nino watch. In the meantime, the IMD predicts a substantial increase in the likelihood of an El Nino emerging during the southwest monsoon in its most recent ENSO advisory, which is dated January 2023. Why is this shift, which is taking place hundreds of thousands of kilometres away, generating concern in the subcontinent?

The effects of El Nio on the Indian summer monsoon:

In India, between June and September, the summer monsoon season brings varying amounts of precipitation. The interannual variability of the monsoon, as it is commonly known, is a result of a variety of variables.

The North Atlantic Oscillation (NAO), Pacific Decadal Oscillations (PDO), IOD (Indian Ocean Dipole), Atlantic sea surface temperature variability, North Atlantic Oscillation (NAO), and more immediate and local factors like dust clouds and irrigation patterns are all thought to contribute to the remaining 70% of the yearly variability.

The gradual development of the El Nino weather patterns this year may result in a shortfall in monsoon rainfall, experts have warned. They are concerned that this might have a severe impact on the ecosystem as it develops in a world shaken by climate change. Although the IMD has not made a formal announcement about the risk of El Nio disrupting the summer monsoon, it is obvious from rainfall trends in India over the past 132 years that El Nino episodes have always been linked to severe droughts in India.

During an El Nino year, there is a 60% chance that India would experience a drought, and while there is a 10% chance that it will rain normally, there is a 30% chance that it won't rain at all.

The devil is in the details, despite the fact that the top-line of IMD's first monsoon projection for 2023 screams "normal" monsoon this year. A deeper look reveals that the projected likelihood really indicates a possibility of greater than 50% that the monsoon would be below average.

In a map, a larger portion of the nation is predicted to have below-average precipitation compared to regions that are predicted to experience above-average precipitation. Also, historically, a change from a La Nia winter to an El Nino summer typically results in the highest deficit in the monsoon-around 15%-and denotes the likelihood of weaker pre-monsoon and monsoon circulations.

Between 1951 and 2022, there were 15 moderate to strong El Nino occurrences, according to historical data. In these years, the Indian monsoon was insufficient 8 times, and the rainfall during the monsoon was below average 3 times.

There is a 73% likelihood that India's monsoon rainfall will go below the long-term average in a year with a moderate to strong El Nino. The Indian monsoon rainfall was 13% lower in 2015, the latest significant El Nino episode. El Nio circumstances have a reputation for being unpredictable, therefore it is too early to say how they may impact Kerala and the rest of India's monsoon season.

However, according to a forecast from private weather service Skymet, the forthcoming monsoon will be "below normal" by 94% (with a +/-5% error margin) of the long-period average (LPA) of 868.6mm from June to September. India's northern and central regions run the risk of experiencing a lack of rain. While July and August will see insufficient precipitation in Gujarat, Madhya Pradesh, and Maharashtra, the second half of the season will be more likely to see below-average rainfall in Punjab, Haryana, Rajasthan, and Uttar Pradesh.

Can positive IOD save Monsoon 2023 against El Niño: Prediction skills for an IOD (Indian Ocean Dipole) remain low and even more importantly, the impact of IOD on the monsoon is not very robust. It is likely that the monsoon itself impacts the IOD. If an IOD does occur following a normal monsoon, then the chicken-and-egg narrative will play out again. But remembering that the monsoon is a monstrous heat source and IOD mostly occurs after the monsoon has nearly ended, we must focus on late season extremes in dry and wet spells.

Such late season anomalies tend to come from outside the tropics as well; for ex., because of the planetary waves driven by Arctic warming and Arctic Sea ice anomalies. It is thus critical to understand what is driving the near-normal monsoon forecasts. As usual, it is important to hope for the best and prepare for the worst in terms of food, water, energy, health, transportation and other sectors.

How will El Nio affect India's agricultural output?

El Nio is the opposite of La Nia in that it is connected with poor rainfall in Southeast Asia. Trade winds deteriorate and warm water is pushed eastward towards the west coast of the Americas during El Nino. Evaporation is made possible by warm waters, which drop pressure and allow air and moisture to rise. In the heights, the moisture condenses to create clouds, storms, torrential rain, and floods.

The opposite occurs in Asia, where the waters cool, the air descends, builds pressure, and clear skies and below-average rainfall result. Poor southwest monsoon rainfall across India could have an impact on the output of Kharif (summer and autumn) crops like paddy, groundnut, legumes, sugarcane, and cotton. The onset of an El Nino phase is always bad news for agriculture. El Nio will hinder output in addition to having an impact on farm income and rural expenditures.

Concerns have been voiced by the finance ministry regarding India's potential exposure to El Nio circumstances. The ministry stated that "certain meteorological institutions expect the return of El Nino conditions in India this year" in its monthly economic report for January. If these forecasts are correct, there may not be enough monsoon rains, which would result in poorer agricultural output and higher costs.

The agriculture industry in India would unavoidably be impacted by a severe pre- and post-monsoon phenomenon. Agriculture crops are already at risk due to the increasing heat. In several areas of the country, like Lasalgaon in Maharashtra, rising temperatures have caused an increase in onion prices. Moreover, Punjab, Uttar Pradesh, Bengal, Haryana, Gujarat, and Maharashtra reported a substantial decline in potato prices.

The majority of northeast India, east and central India, and certain areas of northwest India have been designated to have above-normal maximum temperatures, according to the India Meteorological Department (IMD). For the rest of the nation, normal to below-average maximum temperatures are anticipated. Parts of Bihar, Jharkhand, Uttar Pradesh, Orissa, West Bengal, Chhattisgarh, Maharashtra, Gujarat, Punjab, and Haryana are expected to experience heatwaves.

The Ministry of Agriculture is however optimistic and has predicted a record 112.18 million tonne (MT) of wheat production for the current harvest season (July-June), while completely excluding any significant loss in grain yield from recent unseasonal rainfall in important states. Between 8-10% of the wheat crop has been predicted to have suffered damage recently as a result of unseasonal rainfall and hailstorms in producing states, although better yield prospects in late-sown areas are expected to make up for the production loss.

Is India ready to suffer losses?

The Rabi season of 2022-2023 witnessed a record amount of mustard sown in India. Yet recent rain storms that were recorded in January hurt the crops in a few different regions. According to data submitted by the agriculture department, there are 9.7 million hectares (ha) of mustard growing throughout the world.

Around 700,000 hectares greater than the previous season. Moreover, the increase in acres was greater than that of rival crops. However, the bumper crop's productivity was impeded in some sections by cold waves, which in some parts of the northern belt caused ground frost.

The worst damage was observed in Sirohi, Churu, Ajmer, and Udaipur. India is anticipated to see losses in the Alphonso mango industry as well. Due to the delayed blossoming, the mango production in the Dharwad area of Karnataka is predicted to be poor this year. In Uttar Pradesh as well, the mango crop has been harmed by unseasonal rain and hailstorms. While the Mall-Malihabad belt, one of the state's major mango-producing regions, may have lost up to 35% of its production, other districts may have suffered 20 to 25% in crop damage.

If El Nino predictions come true, they will compound the harm that unseasonal rain and heat waves have already done to the agricultural industry. The IMD's beige forecast appears to have temporarily soothed worries. Beyond normal seasonal rainfall, it's likely that how the rains are distributed will have the most impact on how India experiences the monsoon this year.