Evidence of a possible link between El Nino and a severe flu pandemic in 1918 that adversely affected India, has been shown by a new research conducted at Texas A and M University, US.
The findings are based on analysis of the 1918 El Nino, which the new research shows to be one of the strongest of the 20th century.
El Nino occurs when unusually warm surface waters form over vast stretches of the eastern Pacific Ocean and can affect weather systems worldwide.
Using advanced computer models, Benjamin Giese, a professor of oceanography who specializes in ocean modeling, and his co-authors conducted a simulation of the global oceans for the first half of the 20th century and they found that, in contrast with prior descriptions, the 1918-19 El Nino was one of the strongest of the century.
Giese said that there were few measurements of the tropical Pacific Ocean in 1918, the last year of World War I, and the few observations that are available from 1918 are mostly along the coast of South America.
''But the model results show that the El Nino of 1918 was stronger in the central Pacific, with a weaker signature near the coast,'' he said. Thus the limited measurements likely missed detecting the 1918 El Nino,'' he added.
According to Giese, ''The most commonly used indicator of El Nino is the ocean temperature anomaly in the central Pacific Ocean. By that standard, the 1918-19 El Nino is as strong as the events in 1982-83 and 1997-98, considered to be two of the strongest events on record, causing some researchers to conclude that El Nino has been getting stronger because of global warming.''
''Since the 1918-19 El Nino occurred before significant warming from greenhouse gasses, it makes it difficult to argue that El Ninos have been getting stronger,'' he said.
The research also raises questions about El Nino and mortality from the influenza pandemic of 1918.
By mid-1918, a flu outbreak, which we now know was the H1N1 strain that is of great concern today, was sweeping the world, and the resulting fatalities were catastrophic.
At least 25 million people died worldwide, with some estimates as high as 100 million deaths.
India was particularly hard hit by the influenza.
''We know that there is a connection between El Nino and drought in India,'' said Giese.
''It seems probable that mortality from influenza was high in India because of famine associated with drought, so it is likely that El Nino contributed to the high mortality from influenza in India,'' he added.