Aerosol Impact on Climate in the Himalayan Region

December 14, 2023

A recent study conducted by the Indian Space Research Organization’s (ISRO) Physical Research Laboratory reveals alarming increases in aerosol levels, particularly over the Indo-Gangetic Plain (IGP) and the Himalayan foothills. The study’s ground-based observations emphasize the implications of these heightened aerosol levels, potentially leading to increased temperatures, altered rainfall patterns, and accelerated melting of glacier ice and snow.

Aerosol Radiative Forcing Efficiency (ARFE) Findings

The study indicates a high Aerosol Radiative Forcing Efficiency (ARFE) in the atmosphere over the IGP and the Himalayan foothills, ranging from 80 to 135 Wm−2 per unit aerosol optical depth (AOD). This efficiency is notably higher at elevated elevations. The primary drivers behind the accelerated glacier and snow melt are attributed to aerosol-induced atmospheric warming and the deposition of light-absorbing carbonaceous aerosols on snow and ice.

Dominance of Black Carbon Aerosol

Black carbon aerosol (BC aerosol) is reported to dominate (≥75%) aerosol absorption over the IGP, including the Himalayas throughout the year. Aerosols alone contribute to over 50% of the total warming of the lower atmosphere.

Unique Nature of Aerosol Loading in India

India’s aerosol loading represents a unique case due to varying sources activated at different spatial and temporal scales. This complexity, coupled with diverse land use patterns across the country, creates a challenging aerosol radiation-cloud-precipitation-climate interaction.

Government Initiatives and Research Efforts

Several institutes, universities, and organizations in India have actively researched aerosol properties and their effects under various government initiatives. Funding from the Ministry of Earth Sciences (MoES), Department of Science & Technology (DST), Ministry of Environment Forest and Climate Change (MoEF&CC), Department of Space (DoS), Ministry of Mines (MoM), and Ministry of Jal Shakti (MoJS) has supported these endeavors.

Monitoring Himalayan Glaciers

The Hindu Kush-Himalaya-Tibetan Plateau region, housing the largest ice mass outside the Polar regions, is under scrutiny. Indian institutes, universities, and organizations, funded by the government, actively monitor Himalayan glaciers for scientific studies, including glacier melting. The average retreat rate of Hindu Kush Himalayan glaciers is reported at 14.9 ± 15.1 meters per annum (m/a). The rates vary across river basins, with stable conditions observed in the Karakoram region.

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