El Nio threat

India might have a bad monsoon next year

By T V Jayan
Published: Friday 15 October 2004

climate scientists fear that an episode of El Nio, a dreaded weather phenomenon that causes severe weather disturbances in North and South America and Australia and adversely affects the Indian monsoon, is in the offing.

El Nio, which means the Child in Spanish (refers to Christ since the phenomenon peaks around Christmas), is an abnormal warming of the Pacific Ocean off South America. Normally, the temperature of the surface water in the western Pacific Ocean is 6-8C higher than in the eastern Pacific Ocean. But during El Nio, this reverses, changing the atmospheric pressure on either side of the ocean, a phenomenon known as the El Nio Southern Oscillation. Though scientists are yet to ascertain the strength of the El Nio this time, their observations clearly reveal an anomalous warming up in the central equatorial Pacific Ocean.

The matter of whether El Nio actually influences the southwest monsoon rainfall in India is hotly debated among scientists. Four out of five strong El Nio events in the past have resulted in India receiving less than normal rainfall. The El Nio events in 1965, 1972, 1982 and 1987 were bad for India, but the 1997 El Nio, despite being the strongest in the century, did not affect the southwest monsoon. This led many experts to conclude that the link between the Indian monsoon and the global weather event was wearing off. But the India Meteorological Department (imd) takes into account the El Nio while making its annual monsoon forecast. However, M Rajeeven, imd's director of long range forecasting, says it is too early now to ascertain the impact of the impending El Nio on next year's Indian monsoon.

According to the us National Oceanographic and Atmospheric Administration (noaa), the current warming is 0.2C higher than the minimum required to declare an El Nio. In a report on September 3, 2004, the Geneva-based World Meteorological Organisation (wmo) also warned about an impending El Nio, but said it would give it a fifty-fifty chance. "What we haven't seen yet is the patterns of cloud across the central Pacific become like an El Nio event. If we get a big flare-up in the tropical convection in that area of the globe, that might be enough to tip the scales towards El Nio," said wmo spokesperson Grant Beard.

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