El Nino
This is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current. ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas. The presence of the El Nino leads to an increase in sea-surface temperatures and weakening of the trade winds in the region.
How did it come about?
- El Nino was observed as far back as in the late 1800s when South American fishermen noticed the warming up of coastal waters around Christmas. They referred to it as “El Nino” (Spanish for the boy child), since it appeared around Christmas.
- Sir Gilbert Walker, a British mathematician, discovered the Southern Oscillation (SO), or large-scale changes in sea level pressure across Indonesia and the tropical Pacific. However, he did not recognise that it was linked to changes in the Pacific Ocean or El Nino.
- It wasn’t until the late 1960s that Norwegian-American meteorologist Jacob Bjerknes and others realised that the changes in the ocean and the atmosphere were connected.
- As already mentioned, El Nino has been found to impact almost half the world triggering droughts in Australia, India, southern Africa and floods in Peru, Ecuador, the United States, the Gulf of Mexico, and the Colorado River basin. If Sir Gilbert found in the 1920s that many global climate variations, including monsoon rains in India, were correlated with the SO, the credit of linking it with El Nino as part of ENSO involving both the ocean and atmosphere, goes to Bjerknes. But it took until the 1980s or later for ‘La Nina’ or even the ‘neutral phase’ (neither El Nino or La Nina) to gain currency.
Effects of El Nino
- El Nino affects global weather. It favors eastern Pacific hurricanes and tropical storms.
- Recorded unusual rainfall in Peru, Chile, and Ecuador are linked to the climate pattern.
- El Nino reduces the upwelling of cold water, decreasing the uplift of nutrients from the bottom of the ocean. This affects marine life and sea birds. The fishing industry is also affected.
- Drought caused by El Nino can be widespread, affecting southern Africa, India, Southeast Asia, Australia, and the Pacific Islands. Countries dependent on agriculture are affected.
- WHO report on the health consequences of El Nino forecasts a rise in vector-borne diseases, including those spread by mosquitoes, in Central and South America. Cycles of malaria in India are also linked to El Nino.
- Over India, the El Nino has usually been the harbinger of drought and the La Nina of rain.
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