Long-term variability of air quality and greenhouse gas emissions from rice crop burning in Punjab during 2012–2020

Abstract

Punjab, India's primary rice and wheat production hub, has witnessed rapid expansion of paddy cultivation over the past two decades, driven by minimum support price incentives, changes in government policies, alignment of sowing with the monsoon season and the adoption of high-yielding varieties. This transition has intensified groundwater extraction and shortened the fallow period between rabi and kharif crop seasons, reducing the window between rice harvesting and wheat sowing, leading to widespread open-field burning of rice residue and recurrent post-monsoon air-quality deterioration across the Indo-Gangetic Plain. Despite numerous short-term or single-pollutant assessments, a spatially resolved, multi-pollutant and multi-decadal evaluation linking crop production, fire activity, satellite observations, and future emission trajectories remains limited. In this work, we presented a comprehensive district- and grid-resolved emission inventory for crop residue burning in Punjab for 2000–2020 and integrated it with satellite-derived atmospheric indicators, active fire counts, and scenario-based forecasting. The study quantified particulate (PM_2.5, PM₁₀, black carbon, and organic carbon), gaseous (SO₂, CO, NO_x, and NH₃), toxic organic (NMVOCs and PAHs), and greenhouse gas (CO₂, CH₄, and N₂O) emissions and evaluated their consistency with satellite observations of aerosol optical depth and trace gases. Rice cultivation expanded from ∼0.26 to ∼3.14 million hectares during 2000–2020, accompanied by substantial yield gains, which translated into marked growth in residue generation and emissions. The Malwa region consistently emerged as the dominant multi-pollutant hotspot, whereas Doaba and Majha exhibited lower but rising burdens. Strong statistical relationships between fire counts, estimated emissions, and satellite observations (R² ≈ 0.60–0.81) confirm the robustness of the inventory and demonstrate a direct linkage between residue burning intensity and atmospheric loading. We tried to couple the long-term agricultural production trends with multi-pollutant emission quantification, satellite validation, and grid-wise spatial analysis and explored the scenario-based future projections based on the percentage of residue burnt. Scenario-based forecasts for 2040 indicated that continuation of high residue-burning fractions could lead to substantial increases in pollutant concentrations, particularly in central and south-western districts such as Ferozpur, Hoshiarpur, and Rupnagar. The results establish crop residue burning as a persistent, spatially concentrated emission source, emphasizing the need for location-specific residue management strategies rather than state-specific steps to achieve simultaneous air-quality improvement.