India set to become biggest emitter of sulfur dioxide
By Marc Cherki
Posted
China would have reduced its emissions of SO2 (sulphur dioxide) to the thresholds planned for 2030. But India is accusing a sharp rise in this gas, responsible in particular for acid rain and respiratory problems in humans.
India is set to become the world's biggest emitter of sulfur dioxide (SO2), says a study published November 9 in Scientific Reports, a journal of the Nature group. Between 2007 and 2016, the presence of this harmful gas, responsible in particular for acid rain, a low proportion of fine particles in the air (between 10% and 20%) and respiratory disorders which can become serious in humans, grew strongly in India. The increase there is around 50%, while China has reduced its emissions by 75%, indicates the publication which brought together researchers from the University of Maryland (United States), the prestigious NOAA (National Oceanic and Atmospheric Administration) and in particular a department of the Environment of Canada.
The combustion of coal, the main emitter of SO2
Most sulfur dioxide in the air is produced by burning coal, which contains about 3% sulfur. But since the early 2000s, China has implemented much stricter regulations with regard to these discharges, deciding to fine polluters who exceed the standards and setting targets for reducing SO2 emissions. As a result, levels of sulfur dioxide in the air in the Middle Kingdom have decreased “very sharply, despite a 50% increase in coal consumption and electricity growth exceeding 100% “Said Can Li, first author of the publication and researcher at the University of Maryland and the Goddard Space Center of NASA, the American space agency.
On the other hand, in India, the regulations were introduced later and the country opened its largest coal-fired power stations in 2012. Thus, even if India's greenhouse gas emissions remain 4 times lower than those of China, with respectively 3.1 billion tons of CO2 (carbon dioxide) and 12 billion tons in 2014 (according to data extracted from the "Climate Watch Data" of the American "think-tank" WRI), the country is set to become the world's largest emitter of anthropogenic (man-made) sulfur dioxide, say the researchers.
The originality of this work lies in obtaining data for SO2. First, the researchers estimated emissions from inventories of factories, power plants, automobiles and other contributors to atmospheric releases of sulfur dioxide. But these values are often incomplete and generally old. (With this method, France's CO2 emissions are only known for 2015).
Inventory, satellite and plane measurements
To complete their estimates, the scientists used other data, deduced from the OMI instrument of NASA's Aura satellite, but which only measures significant sources of SO2. New techniques make it possible to estimate the emissions of 500 major sources of sulfur dioxide in the world, including 47 for India and 82 for China. Finally, to calibrate the data deduced from the satellite readings, two scientists estimated the concentrations of SO2 with a meteorological plane which flew over, in 2016, during 11 missions of the industrial zones of the Middle Empire, in the province of Hebei.
It could be estimated that Beijing had already reached its SO2 objectives for 2030. However, Can Li, specifies that these estimates do not reflect the “exact situation on the ground”. As a result, like other scientists around the world, he is campaigning for more data obtained from satellites, even if these values are not always reliable, especially during the passage of clouds which blur the readings.
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