The incidents of crop residue burning (CRB) in Punjab and Haryana causing a spike in the air pollution levels of Delhi and NCR dominate the headlines these days. But what is missed is that CRB has a far-reaching impact on climate change by increasing the load of greenhouse gases and spreading the pollutants to most part of India.
According to a NASA report, CRB is a significant source of both particulate and greenhouse gases such as carbon dioxide, carbon monoxide, nitrous oxide and methane which have both short and long-term impact on global climate systems.
Several studies in the past have already established that CRB impacts not only Delhi and NCR but the entire Indo-Gangetic Plains — from the Arabian Sea to the Bay of Bengal — including central India. A recent study by scientists working in the US and India make some more shocking revelations. They have found evidence that CRB is (a) increasing amounts of black carbon (sooty black material emitted by crop burning) over areas in central and southern India (b) 80 percent or more of all recent methane increase in states like Madhya Pradesh, Maharashtra, Telangana, Chhattisgarh, Bihar, Jharkhand and West Bengal is tied to the transport of methane from the north and (c) contributing 50 percent or more increase in respiratory suspended particular matter and PM2.5 in central and southern India during the month of November. The study also found increasing trends of finer black carbon particles and greenhouse gases have accelerated since 2010.
The scientists attributed this spread of pollutants to a strong high-pressure system that develops over the north-western states of India during winter which causes the wind to flow from the north and north-west towards the south and east. They used multiple data sources including NASA images and ground evidence to over the entire Indian subcontinent for the period 2003–17.
CRB is not restricted to Punjab and Haryana but together with western Uttar Pradesh — all three forming the epicentre of the green revolution and India’ food basket — reports most such incidents. The Government of India’s 2018 ‘operational guidelines’ for in-situ residue management says 23 million ton of paddy residue is burnt every year in these three states – shooting up the levels of carbon dioxide by 70 percent, carbon monoxide by 7 percent and nitrogen dioxide by 2.1 percent. It also says that burning of one ton of rice straw releases 3 kg of particulate matter, 60 kg of carbon monoxide, 1,460 kg of carbon dioxide, 199 kg of ash and 2 kg of sulphur dioxide.
CRB is not restricted to paddy either. The wheat residue is burnt too (April-May). In fact, NASA satellite images have shown that wheat residue burning it is spread all over India. In the winter season (October-November) the severity of CRB (paddy) is felt because of climatic reasons – dispersion of smoke plumes slows down due to cold temperature while in summer it is faster.
The practice of CRB started with mechanised harvesting in 1980s, for both paddy and wheat residues as it leaves taller stubbles of 1-2 ft compared with less than 6 inch in manual harvesting. In Punjab and Haryana, conversations with farmers in half-a-dozen villages revealed that they are forced to burn paddy residue as it is not used as fodder, unlike that of wheat, and a short period between harvesting paddy and sowing wheat leaves them with little choice as paddy residue takes more than a month to decompose and mix with soil – by which time they would have missed wheat sowing.
Increasing risks to health and climate change have forced the Government of India to provide financial assistance to the farmers of Punjab and Haryana for in-situ residue management by way of subsidising in-situ residue management systems such as Happy Seeder, Zero-till Seed Drill, Rotavator, Super-SMS, Straw Baler, Paddy Mulcher etc. In addition, the state governments are spreading awareness and promoting the alternative use of paddy residue – in waste-to-energy plants, brick kilns, production of ethanol, paper/board making and packaging materials etc. But these states have a very little capacity for such use of paddy residue.
The good news, however, is that the CRB incidents are coming down sharply because of the hue and cry raised over a spike in air pollution of Delhi and NCR for the past three years running. Official records show that such incidents have gone down in Punjab from 11,179 in 2016 to 7,613 in 2017 and 2,589 in 2018 (between September 27 and October 21) and in Haryana from about 4,000 in 2017 to 2,600 in 2018 (up to October 21).
But this is a beginning. As mechanisation of harvesting spreads to other states, it would lead to an increase in a load of greenhouse gases and other pollutants posing the same threat there too. Therefore, the attention should be paid to create awareness in the rest of India for timely prevention.
Updated Date: Oct 25, 2018 18:21 PM