High-resolution monitoring of air pollution and climate variability in the Indus-Ganges-Brahmaputra basins: Insights into physical drivers.

The Indus, Ganges, and Brahmaputra river basins are now among the world's most climate sensitive regions, driven by rapid population growth, improper land utilization, extensive land use and land cover (LULC) changes, and worsening air pollution. This study uses several high-resolution and reanalysis datasets, together with the non-parametric statistical techniques and Google Earth Engine (GEE) algorithms, to assess air pollution, climate variability, and their physical drivers across annual, seasonal, monthly, and diurnal timescales from 2010 to 2023. The findings reveal a substantial increase in air pollutants, including sulfur dioxide, nitrogen dioxide, carbon monoxide, ozone, UV absorbing aerosols, and atmospheric formaldehyde, averaging 0.06 mol/m2, along with the concentration of PM2.5 (2.62 μg/m3/year, p < 0.05), indicating growing anthropogenic pressure. A marked reduction was observed during the COVID-19 lockdown (2020), highlighting strong human influence. Seasonal analyses indicate the highest pollutant concentrations during the monsoon and winter, particularly in the Ganges and Indus valleys, driven by industrial emissions, fossil fuel combustion, and biomass burning. Meanwhile, annual precipitation increased significantly in the Ganges basin (89.6 mm per year, p < 0.05), while the Brahmaputra basin experienced a notable decline (119.3 mm per year, p < 0.05). Regional air temperature also increased by 0.68 °C/year, showing strong correlation with pollutant levels (R2 = 0.83). Additionally, LULC analysis shows increases in built up areas (12.8 percent), cropland (2.2 percent), tree cover (1.9 percent), and rangelands (1.2 percent). Consequently, these findings highlight an imperative for concerted environmental monitoring and policy-driven mitigation in this densely populated, highly vulnerable region.