Monsoon warning?

The news of a 60 per cent chance of a weak El Nino developing in early 2005, is surely not welcome, given the possibility that this presages a below-normal monsoon next year as well. However, concern at this stage may be premature.

For, considerable uncertainty still persists concerning future developments in the atmospheric factors that influence the growth of El Nino and its consequences for global weather systems.

In fact, it is good that the international weather agencies and even the UN Food and Agriculture Organisation (FAO) have begun pursuing these developments.

What has caused this alert is the rise in sea surface temperature in the western and central parts of the Pacific Ocean, one of the major harbingers of El Nino.

In fact, these temperatures have been hovering near El Nino threshold for the past three to four months. What is more, the southern oscillation index, another factor responsible for the emergence of El Nino, has also been weakly negative, thus increasing the probability of El Nino's growth.

But, on the positive side, marked atmospheric changes in the Pacific winds and cloud cover that are usually associated with El Nino have not yet appeared. This lends considerable uncertainty to future developments on this front.

Where El Nino's impact on the Indian monsoon is concerned, opinions are sharply divided and for good reason. One school of thought is that there is no one-to-one relation between the emergence of El Nino and poor monsoon rainfall.

This is based on the data for the past 100 years, between 1902 and 2002. Of 23 El Nino years during this period, droughts occurred in only nine of them.

In as many as 14 El Nino years, monsoon rainfall was statistically normal or above normal though its distribution over time and space (which matters for agriculture) varied widely.

On the other hand, some of the foreign agencies that keep track of the global consequences of El Nino opine that the correlation between El Nino and the monsoon is pretty strong, with the statistical correlation coefficient being 0.5.

The India Meteorological Department (IMD) seems rather confused by this whole issue. In the past, it had generally been underplaying the role of El Nino in determining the monsoon's performance.

But when the 2004 monsoon turned out to be poor, rendering the IMD's prediction of 100 per cent normal monsoon untrue, it chose to put the blame on the unforeseen emergence of El Nino.

It maintained that El Nino was neutral till June-end and began appearing subsequently, adversely affecting the rainfall in July. Whatever the truth, it is amply evident that more scientific investigations are needed to understand this complex environmental phenomenon.

The IMD, too, needs to focus on this issue, considering the far-reaching implications the monsoon has for agriculture, fisheries, livestock, hydel power production, navigation, and other sectors, including the availability of drinking water.

Indeed, the economy's dependence on the monsoon may be waning with time but it cannot be wholly insulated against it, at least not in the near future.

What is needed, thus, is more reliable weather predictions, facilitating timely impact mitigation efforts.