The Commission for Air Quality Management (CAQM), in a press release on 30 October, said that the number of stubble burning incidents have reduced by 56 percent in Punjab, and 40 percent in Haryana this year – as compared to the period between 15 September and 28 October in 2022.
These two states, in absolute numbers, contribute to the highest number of stubble burning incidents – which, in turn, is one of the contributors to pollution in the Delhi-NCR region.
These numbers are just early trends – and do not paint the complete picture of farm fires during the harvest season, which will conclude by 30 November.
But apart from the timeframe, scientists point out that this data alone is not enough to establish a decrease in stubble burning incidents – pointing to concerns about the accuracy of the data calculated.
How exactly is stubble burning data calculated in India? What are the concerns? FIT explains.
Dip in Farm Fires in Punjab, Haryana: Is Stubble Burning Data Accurate?
1. What Makes Stubble Burning Data Crucial?
According to the Centre for Science and Environment, stubble burning is the large-scale burning of crop residues from the rice-wheat systems of Punjab, Haryana, and parts of western Uttar Pradesh. How much do these fires contribute to the worsening air quality in Delhi-NCR every winter?
It really depends on which data set you look at, which political party you ask, and the speed and direction of the wind. For instance:
According to an IndiaSpend analysis, data from the System of Air Quality and Weather Forecasting and Research (SAFAR) during October and November 2022 showed that the maximum contribution of these farm fires to the daily PM 2.5 levels in Delhi was 34 percent.
In 2021, the Centre submitted an affidavit to the Supreme Court, claiming that crop-burning residue contributed to just 4 percent of air pollution. But in another section of the same affidavit, the government said stubble burning contributed to 35-40 percent PM 2.5 in Delhi.
How is this data calculated? Dr Gufran Beig, former project director at SAFAR, said that the CAQM protocols suggest the use of NASA's Fire Information for Resource Management System (FIRMS) to track open fires.
"The data that is being collected is from satellites – NASA's Visible Infrared Imaging Radiometer Suite (VIIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS). This is the only technical way possible at this stage in time," Dr Beig told FIT.
"One of the primary methods is to use satellite imagery from platforms like NASA and ISRO. These images can capture large areas and detect the presence of burning fields. It's like taking pictures from space to see where stubble burning is happening," adds Anjal Prakash, Clinical Associate Professor (Research) and Research Director Bharti Institute of Public Policy, Indian School of Business.
While ground observations and air quality monitoring are also deployed – satellite data is the key source of detection, he told FIT.
Expand2. Why Are There Concerns About Satellite Data Sets?
The Count Of Fire Depends on Resolution
"The fire counts on these satellites depend on the resolution. For example, if the resolution is 3km X 3km, it will give you a different count of fire, and if the resolution of the satellite is 400 square meter X 400 square meter, then the count of fire will be different," Dr Beig told FIT.
To break it down, if there is stubble burning on an eight-acre farm in Punjab, it might show different data on farm fire count in two different satellites.
"It should also be noted that depending on the resolution, a single fire may be attributed to the entire area. There is also the possibility that several smaller fires may be counted as one fire – because the resolution of satellite sees it as one area," Dr Beig added.
According to a IndiaSpend report:
The VIIRS sensor aboard the Suomi National Polar-Orbiting Partnership (SNPP) satellite has a resolution of 375 square metre – which equals the size of 17 cricket grounds. The report points out that the average size of a farm is 8 acre – which means that the satellite is about four times the size of an average farm in Punjab.
Expand3. How to Better Track Stubble Burning Incidents?
Murtugudde suggests that while flying a drone over concerned areas could be considered to monitor and collect data on stubble burning, this could be a more expensive approach.
Like Murtugudde, Prakash too suggests, crowdsourcing and engaging with locals to report on stubble burning.
"Efforts are underway to develop more effective systems to track crop burnings in India. These include the use of advanced satellite technology, machine learning algorithms, and drones for more precise and real-time monitoring," he said.
By improving ground-level reporting and community engagement will not only enhance data accuracy, it will also encourage farmers to adopt alternative crop residue management techniques, the professor added.
"Collaboration between government agencies, environmental organisations, and technology companies can help create a comprehensive and integrated system for tracking crop burnings. These approaches aim to not only improve data accuracy but also promote sustainable agricultural practices and reduce the environmental impact of stubble burning," Prakash said.
(At The Quint, we are answerable only to our audience. Play an active role in shaping our journalism by becoming a member. Because the truth is worth it.)
Expand
What Makes Stubble Burning Data Crucial?
According to the Centre for Science and Environment, stubble burning is the large-scale burning of crop residues from the rice-wheat systems of Punjab, Haryana, and parts of western Uttar Pradesh. How much do these fires contribute to the worsening air quality in Delhi-NCR every winter?
It really depends on which data set you look at, which political party you ask, and the speed and direction of the wind. For instance:
According to an IndiaSpend analysis, data from the System of Air Quality and Weather Forecasting and Research (SAFAR) during October and November 2022 showed that the maximum contribution of these farm fires to the daily PM 2.5 levels in Delhi was 34 percent.
In 2021, the Centre submitted an affidavit to the Supreme Court, claiming that crop-burning residue contributed to just 4 percent of air pollution. But in another section of the same affidavit, the government said stubble burning contributed to 35-40 percent PM 2.5 in Delhi.
How is this data calculated? Dr Gufran Beig, former project director at SAFAR, said that the CAQM protocols suggest the use of NASA's Fire Information for Resource Management System (FIRMS) to track open fires.
"The data that is being collected is from satellites – NASA's Visible Infrared Imaging Radiometer Suite (VIIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS). This is the only technical way possible at this stage in time," Dr Beig told FIT.
"One of the primary methods is to use satellite imagery from platforms like NASA and ISRO. These images can capture large areas and detect the presence of burning fields. It's like taking pictures from space to see where stubble burning is happening," adds Anjal Prakash, Clinical Associate Professor (Research) and Research Director Bharti Institute of Public Policy, Indian School of Business.
While ground observations and air quality monitoring are also deployed – satellite data is the key source of detection, he told FIT.
Why Are There Concerns About Satellite Data Sets?
The Count Of Fire Depends on Resolution
"The fire counts on these satellites depend on the resolution. For example, if the resolution is 3km X 3km, it will give you a different count of fire, and if the resolution of the satellite is 400 square meter X 400 square meter, then the count of fire will be different," Dr Beig told FIT.
To break it down, if there is stubble burning on an eight-acre farm in Punjab, it might show different data on farm fire count in two different satellites.
"It should also be noted that depending on the resolution, a single fire may be attributed to the entire area. There is also the possibility that several smaller fires may be counted as one fire – because the resolution of satellite sees it as one area," Dr Beig added.
According to a IndiaSpend report:
The VIIRS sensor aboard the Suomi National Polar-Orbiting Partnership (SNPP) satellite has a resolution of 375 square metre – which equals the size of 17 cricket grounds. The report points out that the average size of a farm is 8 acre – which means that the satellite is about four times the size of an average farm in Punjab.
Infrequent Satellites
"Satellites are used to map areas burning. These satellites do not pass every day or pass overhead infrequently and their pixel sizes can be too big to make accurate estimates," said Raghu Murtugudde, an Earth Scientists and Professor at Indian Institute of Technology Bombay.
The SNPP satellite is said to give a global coverage every 12 hours. This means that when there is fire in one field, and it goes on for 30-odd minutes, then the satellite is not really around to track this data, and it does not get recorded.
"Unlike forest fires, which continue for a longer period of time over a larger area, agricultural fires are small incidents. It occurs in one field after another and persists for hardly 15-20 minutes to half an hour. So, if the satellite is not there at this time, those fires are not picked up," Vinay K Sehgal from the Consortium for Research on Agroecosystem Monitoring and Modelling from Space (CREAMS) explained to IndiaSpend in 2022.
How to Better Track Stubble Burning Incidents?
Murtugudde suggests that while flying a drone over concerned areas could be considered to monitor and collect data on stubble burning, this could be a more expensive approach.
Like Murtugudde, Prakash too suggests, crowdsourcing and engaging with locals to report on stubble burning.
"Efforts are underway to develop more effective systems to track crop burnings in India. These include the use of advanced satellite technology, machine learning algorithms, and drones for more precise and real-time monitoring," he said.
By improving ground-level reporting and community engagement will not only enhance data accuracy, it will also encourage farmers to adopt alternative crop residue management techniques, the professor added.
"Collaboration between government agencies, environmental organisations, and technology companies can help create a comprehensive and integrated system for tracking crop burnings. These approaches aim to not only improve data accuracy but also promote sustainable agricultural practices and reduce the environmental impact of stubble burning," Prakash said.
(At The Quint, we are answerable only to our audience. Play an active role in shaping our journalism by becoming a member. Because the truth is worth it.)