The Indian government’s prediction of near-normal monsoon rainfall glosses over the likelihood of scarce rain in June, when it is most important for rainfed farming
The India Meteorological Department (IMD) has forecast that rainfall during the 2019 summer monsoon will be 96% of the 1951-2000 long-period average (LPA), a situation it describes as “near normal”.
Coming in the middle of an election to the Indian Parliament, this forecast is more optimistic than the one made by Skymet, India’s only private meteorological forecasting firm. IMD also says that by the end of July, the El Niño phenomenon will weaken more than predicted by Australian scientists. El Niño is an oscillation of a Pacific Ocean current off the coast of Chile, which results in depressing the monsoon over South Asia.
IMD also says the probability of a “deficient” monsoon is 17%, of “below normal” 32%, of “near normal” 39%, and of “above normal” 10%.
Skymet had forecast that this year’s rainfall would be about 93% of the LPA, which is 887 mm for the four monsoon months. It had also predicted deficient rainfall in eastern and central India in June and July.
With 52% of Indian farmers dependent on monsoon rainfall, this forecast is crucial for the economy and for the ruling Bharatiya Janata Party (BJP) in the outgoing government. An optimistic rainfall forecast helps the BJP strengthen its message that the country has done well in the last five years. It does not help the opposition parties, which have farmers’ distress as their principal campaign plank.
For the rain-dependent farmers themselves, this forecast hides more than it reveals. A weak start to the June-September monsoon will mean they will either not be able to sow their main summer (called Kharif) crop on time, or risk the plants withering if the rain fails. It does not really help them much if the rainfall picks up in August and September, because if they wait for that it will mean very late sowing, and they may not be able to get their crops to the market at the usual time in October or November.
However, if the monsoon picks up it does help replenish groundwater as well as lakes, ponds and reservoirs of all sorts that supply water to the country for most of the eight months when there is hardly any rainfall in South Asia.
The IMD has been criticised in the past for making these macro monsoon forecasts without breaking them up in terms of time or geography, important in a country as large as India. The scientists in the IMD have been working on micro forecasts, and have been putting them out regularly through a service called Agromet, but these do not get as much publicity as the big announcements and therefore do not affect overall sentiment in the country to the extent the big forecasts do. For example, the day after the “near-normal” forecast was made, India’s main stock market showed a sharp rise.
While making this year’s announcement, secretary in the Ministry of Earth Sciences M. Rajeevan was careful to say there could be a 5% margin of error either way. That is scientifically the right thing to do, but the record of IMD forecasts in the last ten years shows that it has been too optimistic with its rainfall forecasts for eight out of those ten years.
And that matters, because rainfall that is 96% of the LPA is near-normal, but rainfall that 91% of the LPA means a near-drought, as happened last year. In the 18 completed years of this millennium, India has already seen 11 drought years. Across the country, but especially in the Deccan Plateau, the groundwater level is perilously low.
The good news in the forecast is that the IMD expects this year’s rainfall to be well distributed across the country. The distribution of rainfall was erratic last year, with normally-rainy north-eastern India getting 78% of the LPA for the region, though the IMD had forecast 93%.
Scientists around the world have suspected a connection between climate change and the increasingly erratic monsoon, though the IMD has said no direct correlation has been established. However, the one big impact of climate change on the water cycle – fewer rainy days but more intense rainfall on those days – is being seen in the Indian monsoon more and more often.