El Nino and the Monsoon

El Nino and the Monsoon
 

News: IMD predicts that El Nino this year is expected to strike late in August.
 

Background:
 India has had four consecutive years of good monsoons and overall rainfall from 2019 to 2022, helped by a prolonged La Nina event. However, this year could see an El Nino.
 In this context, we will understand El Nino, La Lina and its impact on India’s weather, rainfall, agriculture and economy.
 

What is La Nina?
 La Niña basically refers to an abnormal cooling of the central and eastern Pacific Ocean waters off the coasts of Ecuador and Peru.
 Such cooling (Sea-surface temperature falling 0.5 Degree Celsius or more below a 30-year average for at least 5 successive 3 month periods) is a result of strong trade winds blowing west along the equator, taking warm water from South America towards Asia.
 The warming of the western equatorial Pacific, then, leads to increased evaporation and concentrated cloud-formation activity around that region, whose effects may percolate to India as well.

What is El Nino?
 During El Niño, the trade winds weaken or even reverse: Instead of blowing from east (South America) to west (Indonesia), they could turn into westerlies.
 As the winds blow from the west to east, they cause the masses of warm water to move into the central and eastern equatorial Pacific Ocean. The rise in SSTs there, thus, produces increased rainfall along western Latin America, the Caribbean and US Gulf Coast, while depriving Southeast Asia, Australia and India of convective currents.
 

What is Impact of El Nino on India? Does it lead to Drought?
 In 1997, India faced the strongest El Nino ever, but the monsoon was normal (A phenomenon of Indian Ocean Dipole IOD being the reason behind it)
 A slippage of one percentage point in monsoon rainfall will mean a below-normal monsoon.
 El Nino directly impacts India’s agrarian economy as it tends to lower the production of summer crops such as rice, sugarcane, cotton, and oilseeds.
 While all drought years have invariably been El Niño years, the reverse doesn’t hold true though.
 Droughts are no longer the disaster they used to be, thanks to a significant leap in farm productivity. The country’s food output has risen sharply from about 50 million tonnes in 1950-51 to 323.5 million tonnes during 2022-23.

What needs to be done to be prepared for El Nino year?
 Experts have suggested that early sowing can lead to a large part of the harvest being normal.
 Irrigated land in India has jumped from 34.5% of sown area in 2013-14 to 45% in 2022. This has weatherproofed India’s crops to some extent.
 The IMD is basically counting on El Niño’s impact being neutralised by “positive” Indian Ocean Dipole (IOD) conditions developing during the season. To the extent a positive IOD — warmer temperatures in the Arabian Sea waters relative to that in the eastern Indian Ocean — cancels a weak El Niño, as it happened in 2006, the monsoon could well turn out “normal”.
 The government must, to start with, keep a close watch on wheat procurement. If that is low, indicative of significant crop damage from the recent unseasonal rains, it should lose no time in allowing imports.
 Sophisticated weather models, proactive trade policy and improved irrigation, transport and other infrastructure should make it easier to deal with monsoon failures.