Effect of El Niño on southwest monsoon rainfall and agriculture in India.

4. Rao, K. R. , Curr. Sci., 2008, 94, 581–586. 5. Abrol, D. P., Curr. Sci., 2014, 107, 940. 6. Patel, P., Curr. Sci., 2014, 107, 1094. GOVINDASAMY AGORAMOORTHY College of Environment and Health Science, Tajen University, Yanpu, Pingtung 907, Taiwan e-mail: agoram@mail.nsysu. edu.tw Effect of El Niño on southwest monsoon rainfall and agriculture in India The southwest (SW) monsoon (June– September) impacts over 1.7 billion people of the Indian subcontinent and is crucial for the agriculture-dominated economy of India. Weather prediction agencies from all over the world forecast El Niño conditions in 2014 with imminent danger of drought. The frequency of such events has been high in the last decade with droughts in 2002, 2004 and 2009. El Niño-like conditions leave countries like India, Indonesia and Australia drier, increasing chances of wildfires and lower crop production, while leading to heavier rainfall in the eastern Pacific and South American nations, raising the spectre of floods and landslides. India is expected to be the first to suffer, with weaker monsoon rains, undermining the nation’s fragile food supply. El Niño is a weather condition that occurs when surface temperatures in the Pacific Ocean continuously rise above average for several months, which in turn affects wind patterns and triggers floods and droughts in different parts of the world. Usually, average increase of more than 0.5C during a specific duration culminates in the El Niño effect and the current forecasts indicate that this year’s warming will most probably lie between 0.5C and 1.5C (ref. 1). On an average, El Niño occurs every 3–5 years, often begins to form during June–August, and typically lasts 9–12 months. The latest El Niño prediction has come from the European Centre for Medium-range Weather Forecasts (ECMWF), which is considered to be one of the most reliable prediction centres around the world. According to their prediction, the amount of warm water in the Pacific is now significant, perhaps the biggest since the worst El Niño of 1997–98 which is regarded as the biggest such event of the 20th century that caused widespread droughts in the tropics leading to forest fires, with an estimated economic loss exceeding 20 billion USD in Southeast Asia. The El Niño produced the hottest year on record at that time and had major global impacts, including a mass die-off of corals. Various findings indicate that El Niño likely improves the global mean soybean yield by 2.1–5.4%, but appears to change the yields of maize, rice and wheat by –4.3% to 0.8% (ref. 3). India Meteorological Department (IMD) has forecast a 60% probability of El Niño in 2014 along with a below-normal monsoon projection. The SW monsoon is more important as it accounts for over 75% of the annual rainfall in most parts of India. The country had 43% deficit in rainfall in June, which was reduced to 22% by the end of July 2014. Overall, monsoon was 90.3% of normal in July. But, the worrying factor is the higher rainfall deficit of 58% and 54% in Punjab and Haryana respectively, which are considered as the graneries of India. Among all the regions, northwest India reported the highest rainfall deficiency of 34% followed by 26% in the east and North East. The central region reported 12% deficiency, while the South Peninsular region had 19% rain deficit by the end of July. There is a strong relation between El Niño and Indian droughts since 1950, as the country has faced 13 droughts and 10 of these were in the El Niño years. It may be worth noting that since 1980, all the six droughts faced by India were in the El Niño years, but still not all El Niño years led to drought in the country. Since 2000, there were four El Niño years (2002, 2004, 2006 and 2009), and three of these (except 2006) resulted into drought years. The year 2006, which was an El Niño year, however, received normal monsoon rainfall. This situation has been explained by the phenomenon of equatorial Indian Ocean oscillation (EQUINOO). EQUINOO plays an important role in the inter-annual variation of the SW monsoon and it involves a see-saw like situation between a state with enhanced rainfall over western equatorial Indian Ocean and suppressed rainfall over eastern equatorial Indian Ocean (favourable phase) and another state with opposite signs of east-west rainfall anomalies. The ultimate precipitation of the monsoon appears to depend to a large extent on whether the phases of El Niño and EQUINOO are favourable or not. In the six El Niño years, EQUINOO was unfavourable and thus leading to droughts. On the contrary, favourable phase of EQUINOO in 1963, 1997 and 2006 negated the effect of El Niño and resulted in higher rainfall. But this relation appears to have strengthened