With an El Niño brewing, there is disquiet over what that might mean for the coming monsoon. Many droughts experienced by this country have, after all, been associated with the exceptional warming of the equatorial waters of the Pacific that is characteristic of an El Niño. The forecast issued by the India Meteorological Department (IMD) on Thursday is in line with other predictions that warn of poor rains this year. Using a statistical model, the met agency has put a 33 per cent probability of the monsoon being ‘below normal’, a category where nationwide rainfall during the season is between 90 per cent and 96 per cent of the long-period average. That is almost twice the climatological probability based on how the monsoon fared in past years. The IMD forecast, however, also indicates a significantly enhanced risk this year of nationwide rainfall during the monsoon slipping below 90 per cent of the long-period average and turning ‘deficient’. Such a monsoon would, in the parlance used by atmospheric scientists, be considered as having ended in a drought.
There is already a substantial body of unusually warm water below the surface in the tropical Pacific; this water, if it comes to the surface, can trigger an El Niño. The IMD has placed a 60 per cent probability of such an event occurring during the monsoon season. It must be borne in mind that not every El Niño leads to a drought over India. Indeed, an analysis found that the monsoon became deficient in only 43 per cent of the El Niño events that took place between 1880 and 2005. Although an El Niño looks probable this year, it is not yet possible to say how big it might turn out to be. Moreover, the fact of which part of the Pacific warms also influences its impact on the monsoon. El Niño events where the surface waters of the central Pacific heat up have been found to retard the monsoon more than ones where the eastern Pacific warms. In addition, favourable conditions in the Indian Ocean can counter any adverse influence from the Pacific. That famously happened in 1997 when, despite an exceptionally strong El Niño, the country enjoyed slightly above average rains. This year, there is no indication as yet that the Indian Ocean might lend a helping hand. Even if no drought ensues, an El Niño can seriously reduce rainfall, particularly during the opening and closing phases of the monsoon. For agriculture especially, the distribution of rainfall across the season is vital. With the possibility of a bad monsoon this year, water conservation and the harvesting of as much rainwater as feasible become particularly important. For its part, the new government that will be voted to power in Delhi must prepare for any eventuality.