Beware the present dry spell might just get worse. The effect of El Nino, a climatic cycle that affects rainfall all over the world, has got a stranglehold over monsoon causing a shortage of over 60 per cent rainfall across the country since it hit the Indian shores a month ago.
For decades now, scientists have been mystified by the El Nino, unable to predict it until the surface temperature of the ocean rises up to two degrees. A recent breakthrough by Prof Raghu Murtugudde, who graduated from the Divecha Center for Climate Change at IISc and is now at Columbia University, is being described by experts as “one of the holy grails in our understanding of climate change”. Prof Murtugudde and his discovery will enable scientists to predict the El Nino 18 months in advance, giving governments ample time to make emergency preparations for the different countries.
“The El Nino effect affect the monsoon, typically at the beginning (May/June) and the end (September). June only contributes 20% to total seasonal rain, so there is hope that the monsoon may still pick up pace. The pattern this year looks more like in 2010 when the monsoon trough was stuck further south than normal, but was near normal in the end” Prof Raghu Murtugudde said.
“Strong trade winds in the Pacific which blow from the northeast and the southeast converge into the region called the Intertropical convergence zone – the band with rain,” explains Prof Murtugudde. These winds are dragged westward along the Equator, where the Coriolis Effect drags the water toward the Tropics. At some point, the trades weaken and the warm water piling up in the west begins to discharge, depriving the world of its monsoons.
The El Nino has been the curse of farmers and everybody else who depends on the monsoons in most parts of the world. Originating in what is called the Pacific Warm Pool, which contains the warmest seawaters in the world, the El Nino (the warm current) and its sister, the La Nina (the cold spell) have been known to wreak havoc across continents whenever they rise. It is known to cause droughts, floods, hot spells, dry spells and waves so high and violent that they can strip away miles of beach in one night.
“Our study gives the very first solid timeline for the onset of all El Ninos,” says Prof Murtugudde. “This gives us a very specific thing to look for at the end of each year, so we can track progress and understand whether or not an El Nino will develop.” The El Nino remains apparently unaffected by climate change, according to the Professor, which only adds to its intrigue. Moreover, the conditions that Prof Murtugudde and his student, Nandini Ramesh, have zeroed in on remain common to all the different kinds of El Nino, though he still refers to its origin as ‘immaculate conception’. Any theories on this conception? “The work indicates some intriguing role for the monsoons and the ecosystem fighting the huge heat engine, the monster sitting in the western Pacific warm pool,” explains Prof Murtugudde. “So it appears to be one system and who kicks who depends on the time of the year when one is vulnerable to the other. It’s really immaculate.”