Monsoon in India is changing its patterns

Incessant heavy rainfall and floods occurring over peninsular India indicate a radical change in the monsoon patterns. The IMD (Indian Meteorological Department) report, published on March 30, 2021 showed the variability and changes in the monsoon rainfalls of 29 states and Union territories at state as well as district levels.

The report, which was based on 30 years of observational data, cited that over the years between 1989 to 2018, Uttar Pradesh, Meghalaya, West Bengal, Nagaland and Bihar, have witnessed drastic decrease in Southwest monsoon rainfall. This report was presented in the Lok Sabha where the government stated that in addition to these five states, Arunachal Pradesh and Himachal Pradesh have also shown a drastic decrease in monsoon rainfalls. On the contrary, a remarkable increase in the frequency of heavy rainfall over Saurashtra and Kutch, northern region of Tamil Nadu and Andhra Pradesh, South-western region of Odisha, South-eastern Rajasthan, and different parts of many other states has been observed.

Possible causes for diversified monsoon rainfall over peninsular India:

• Climate change: With an exception of Siberian High, the whole of Northern Hemisphere, including the oceans, have shown a warmer temperature from January to October 2021. This has led to the formation of a low-pressure system locally, which has contributed into delayed monsoon withdrawals.
• Arctic Sea–ice loss: The rapid melting or loss of ice in the Arctic sea resulted in a high sea-level pressure over the West European region as well as over the North Eastern parts of China. This moved the planetary waves in the Southeastwards regions, which were earlier trajected to move in the eastwards regions. These waves brought up circulation anomalies in the upper atmospheric regions, which when entered the Indian terrain led to delayed monsoons.
• Madden –Julian Oscillation (MJO): In January 2022, La Niña situations were prevailing over the equatorial regions of Pacific Ocean, and neutral Indian Ocean Dipole (IOD) conditions were prevailing over and near the Indian Ocean. Usually, when La Niña situations takes place, rainfall is average or below average at the times of north-east monsoon in the southern region of Peninsula. But this year monsoons in certain regions were comparatively higher owing to the favorable conditions of MJO.
• La-Niña: La-Niña is a situation when the temperature of the surface, around the sea over and around the Central Pacific Ocean, is lower than the average temperature. When we talk about Indian sub-continent La-Niña usually enhances the low pressure area formation, thus contributing to high rainfall. Therefore, the atmosphere that is laden with moisture in combination with La- Niña situations could probably create conducive environment for the formation of more low pressure areas leading to heavy rainfall events.
• Warming of the Arabian Sea: In addition to the above reasons, the unusual heating-up of the Arabian Sea since the last ten years is also a major factor for these unexpected patterns of rainfall. This heating-up of the sea surface is causing a higher amount of evaporation, which in turn is creating low pressure areas over that region. On a number of occasions, the coupled effect of these low-pressure systems results in the formation of troughs around the Indian landmass, that leads to widespread rainfall. Troughs are elongated regions that carry winds and rains.

   

Outcomes of the changing monsoon patterns in India:

India’s first official climate change report, the Assessment of Climate Change over the Indian Region, states out the condition of monsoon in the rapidly increasing global warming scenario. This report was published by the Ministry of Earth Sciences (MoES) in the year 2020. The report stated that the monsoon circulation had been observed to weaken since 1951, more specifically in the regions of the Western Ghats and Indo-Gangetic plains. On the other hand, incidents of localized rainfall in certain regions as well as the period of dry spells in between the pouring days during the monsoon has increased.

A study report published in 2021, also reported that though deciduous forests earlier existed in peninsular India, they are being replaced by Savanna grasslands, all because of the weakening monsoons. The Nature Scientific Report stated, ‘monsoon forced evolution of savanna and the spread of agro-pastoralism in peninsular India’.

Fiscal burden such as multiple crop failures is also a major impact of changing monsoons. This situation demands the central as well as the state governments to actively support the farmers. This could be done by raising minimum support prices for all the current seasons’ crops that could be an income source for the farmers.

Change in monsoon rainfalls is directly proportional to the change in food grain yield. Though decrease in the rainfall patterns during the summer monsoon periods leads to the decrease in the crop yields, prolonged rainfall also ends up causing adverse effects on the crops thus leading to reduction in the crop yields.

IPCC (Intergovernmental Panel on Climate Change) scientists have also raised concerns regarding these issues since the last couple of years. The recent report published by IPCC on Oceans and Cryosphere details out on how the oceans are being warmed-up by global warming, and how is this responsible for rapid change in monsoon patterns. The scientists have warned that India should be prepared for long spell of drought or heavy downpour, as this is what is going to be the new normal in the coming decades.