Black Carbon emissions accelerating melting processes in Himalayas: Report

Mumbai: Black Carbon (BC) levels have demonstrated a rising trend across the Himalayan region over the past two decades, with particularly high concentrations observed in the Eastern and Central Himalayas, according to a new study by Climate Trends.

The study - Impact of Black Carbon on Himalayan Glaciers: A 23-Year Trends Analysis - examined NASA satellite data of the Himalayan glaciers from 2000-2023 to evaluate the impact of Black Carbon emissions resulting from burning biomass and fossil fuels. Often referred to as the “Third Pole” for its vast frozen reserves, the Himalayas are facing rapid cryospheric changes that could destabilise water supplies for nearly two billion people across South Asia.

The study by Climate Trends, a Delhi-based research consultancy, shows that Black Carbon concentration in the region rose significantly from 2000 to 2019. The analysis showed that the levels see relative stabilisation between 2019 and 2023, suggesting a possible plateau in emissions or a change in atmospheric conditions.

The study also suggests a strong positive correlation between Black Carbon and snow surface temperature which means that Black Carbon is contributing significantly to enhanced surface warming. Moreover, the negative correlation between Black Carbon and snow depth, even after controlling for temperature, confirms its direct influence on snowpack reduction through albedo modification.

“Reducing black carbon, especially from cookstoves, crop burning, and transport, can offer quick wins for climate and water security. Policy Recommendations to that effect in the Indo-Gangetic Plain can have an immediate effect on reducing black carbon emissions. It is also an effective way to achieve improved air health, which has been ailing the region for many years,” said Aarti Khosla, Director, Climate Trends.

According to the report, the average snow surface temperatures in the Himalayan snow peaks have increased by more than 4°C over the last two decades, from an average of -11.27°C (2000–2009) to -7.13°C (2020–2023). Over the 23-year period, the overall mean temperature increase was -8.57°C.Regions where Black Carbon deposition is higher have higher snow surface temperature and lesser snow depth. The snow depth is reducing at a faster pace where Black Carbon is more. Hence more Black Carbon means higher surface temperature , more snow melt and reduced snow depth. The research reveals that black carbon particles are darkening snow surfaces, lowering their reflectivity (albedo), and making them absorb more solar radiation. This results in faster snow melt.

Black carbon acts like a heat lamp on snow. It darkens the surface, accelerates melting, and triggers a dangerous feedback loop. The good news is Black Carbon stays in the atmosphere for just days or weeks. Reducing emissions can cool the region within years — not decades.

“Glacier melt is accelerating, threatening freshwater resources to nearly two billion people downstream. The Eastern Himalaya consistently exhibits the highest levels of Black Carbon, likely due to its proximity to densely populated and biomass-burning regions. Major sources contributing to Black Carbon include biomass combustion, fossil fuel use, and open burning, particularly in the Indo-Gangetic Plain (IGP), which acts as a hotspot for emissions,” said Dr Palak Baliyan, lead author of the study.