India is on course to surpass China as the world’s largest emitter of anthropogenic sulphur dioxide (SO2) according to a study in Scientific Reports this week. The study reports that since 2007, emissions in China have declined by 75% while those in India have increased by 50%.
China and India are the top two consumers of coal in the world and timely, accurate information on SO2 sources is a required input to air quality models for pollution prediction and mitigation. However, such information has been difficult to obtain for these countries, as fast paced changes in the economy and environmental regulations have often led to unforeseen emission changes.
Can Li and colleagues analysed satellite SO2 data from the Ozone Monitoring Instrument aboard the NASA Aura spacecraft to study changes in SO2 pollution in China and India from 2005 to 2016. The authors found that emissions of SO2 from China peaked at approximately 36.6 megatonnes per year in 2007 and have since been on a generally decreasing trajectory. At 8.4 megatonnes per year in 2016, the level is 26% of that in 2005. In comparison, the authors calculate that India produced approximately 11.1 megatonnes of SO2 per year in 2016.
The authors note that despite this change, haze remains a severe environmental issue in China and argue that it is still important to reduce emissions of other pollutants.