8. Intense Biomass Burning Over Northern India and Its Impact on Air Quality, Chemistry and Climate

The provinces of Punjab, Haryana and western Uttar Pradesh in northwest Indo-Gangetic Plain (IGP) produce two-thirds of India’s food grains, and are widely known as the “breadbasket” of India. This “breadbasket” accounts for roughly a quarter of the total annual fire events observed over India, and hence is a regional hotspot for biomass burning. The enormous amount of aerosols and trace gases, emitted largely from extensive post-harvest crop residue burning in autumn (October–November) and spring (April–May), along with events of wildfires, and domestic consumption of biofuels, unfurls its influence along the length of the IGP under the prevailing meteorological conditions. The elevated levels of pollutants, primarily generated from intense post-monsoon biomass burning over northwest IGP, under the influence of unfavourable meteorological conditions, contribute significantly to the episodes of extreme pollution over the regions downwind of northwest IGP. The downwind region of intense biomass burning experiences high values of particulate matter, including black carbon, organic carbon, ozone, volatile organic compounds and other ozone precursors, resulting in an intense photochemistry and an adverse air quality. Furthermore, excessive smoke aerosols in the atmosphere exert a strong surface cooling, but an overall atmospheric warming, thereby changing the regional radiative balance.