El Nino, La Nina and Indian Agriculture

From time to time, agricultural production is affected by El Nino, an abnormal warming of the Pacific waters near Ecuador and Peru, which disturbs weather patterns around the world.

The 2015 El Nino has been the strongest since 1997, depressing production over the past year. But if it is followed by a strong La Nina, there could be a much better harvest in 2016-17.

The 1997 episode lasted roughly from April 1997 to June 1998. During these 15 months, the Oceanic Nino Index (ONI) – which compares east-central Pacific Ocean surface temperatures to their long-term average and is used by the US National Oceanic and Atmospheric Administration (NOAA) for identifying El Nino events – was consistently positive and greater than 0.5 degrees Celsius.

el nino and indiaThe current El Nino started around February 2015; most climate models predict a return to “neutral” conditions not before May 2016. That makes it just as long as the 1997-98 event. Also, in terms of intensity, it is comparable to that of 1997-98: The most recent Oceanic Nino Index (ONI) value of 2.3 degree Celsius for November 2015-January 2016 tied with the level for the same period of 1997-98.

An extended and strong El Nino explains why India had a deficient south-monsoon and dry weather lasting through the winter this time. The prolonged moisture stress from it has, in turn, impacted both kharif as well as the rabi crop.

Data shows that average agricultural growth in El Nino years since between 1981-82 and 2015-16 has been -2.1 per cent compared with a period average of 3.

El nino and indian agricultureSince 1950, there have been 22 El Nino events of varying durations and intensities, according to NOAA data. But out of the 21 prior to this one, 9 have been followed by La Nina, involving an abnormal cooling of sea surface waters along the tropical west coast of South America with an ONI less than minus 0.5 degrees Celsius.

This phenomenon – there have been 14 such events since 1950 – has been associated with normal-to-excess monsoons in India, which may be a by-product of atmospheric convection activity shifting to the north of Australia.

Now, it is important that some of the strongest El Nino years (1997-98, 1972-73, 2009-10, 1986-87 and 1987-88, ranked in the order of strength and of which the last four produced droughts in India) were followed by La Nina episodes, resulting in bumper harvests.

The possibility of this being repeated in 2016 after the second strongest El Nino on record cannot be ruled out. The figure below shows, for example, that average growth in La Nina years was 8.4 per cent, substantially higher than the period average.

But there is a big catch. El Nino, as of now, continues to be “strong” and is only gradually weakening. It will enter neutral zone only with the onset of summer. NOAA’s latest forecast assigns only a 22 per cent probability of La Nina developing in June-July-August, going up to 50 per cent for September-October-November.

The Australian Bureau of Meteorology suggests the “neutral” state as the “most likely for the second half of the year”.

In other words, one shouldn’t expect La Nina conditions to develop before the second half of the southwest monsoon season (June-September). Even if it develops, the translation into actual rainfall in India could take time.

The effects of the 2015 El Nino, after all, were felt only from July, although the east-central Pacific sea surface temperature anomalies began in February.

In sum, La Nina is unlikely to deliver its full bounty in the coming monsoon, or at least not until late in the kharif season. That doesn’t, however, mean the monsoon is going to be bad, especially when all models are pointing to a very low probability of a repeat El Nino happening this year. The monsoon could also be good due to other favourable factors such as a “positive Indian Ocean Dipole”.

The latter phenomenon – where the western tropical Indian Ocean waters near Africa become warmer relative to those around Indonesia – prevented at least two El Nino years (1997 and 2006) from resulting in droughts in India.

The policy implication of such a cautious prognosis is that the government should be ready with a contingency plan for a monsoon, especially after two successive drought years.

Declaring minimum support prices well before kharif sowing operations, incentivizing farmers to produce crops most prone to domestic supply pressures (such as pulses), and timely contracting of imports of sensitive commodities would be essential components of this strategy.