A new study by Climate Trends finds that Black Carbon emissions have raised Himalayan snow surface temperatures by over 4°C in two decades, accelerating glacier melt. The Eastern Himalayas are most affected due to emissions from biomass and fossil fuel burning. Experts call for urgent reduction of Black Carbon, a short-lived pollutant, as a rapid climate mitigation strategy.
The study titled "Impact of Black Carbon on Himalayan Glaciers: A 23-Year Trends Analysis" was conducted by Climate Trends, a Delhi-based research consultancy. The findings were released on May 30, 2025, in New Delhi.
These findings are important because they highlight how Black Carbon emissions are accelerating glacier melt in the Himalayas, a region that supplies freshwater to nearly two billion people across South Asia.
Anjal Prakash, Associate Professor, ISB and IPCC Author highlighted the findings that the rise in surface temperatures is threatening water supplies for two billion people. “Darkening snow surfaces due to Black Carbon reduces albedo, trapping more heat and pushing glaciers to vanish faster. A rapid climate mitigation strategy, targeting Black Carbon from biomass burning and fossil fuels can help cool the region within years,” Prakash said.
He called for immediate action on emissions from cook stoves, agriculture, and transport critical, stating that reducing Black Carbon offers a quick win for climate health, preserving precious water resources and safeguarding vulnerable communities downstream.
The increase in snow surface temperatures threatens water security, agriculture, and climate stability in the region. Since Black Carbon is a short-lived pollutant, reducing it offers a quick, effective way to slow warming, preserve glaciers, and improve air quality.
Earlier this year, the United Nations declared 2025 the International Year of Glaciers, aiming to raise global awareness and push for urgent action to preserve glaciers, their critical role in sustaining life on Earth. A recent report revealed that glaciers in the Himalayas have shrunk by 5 to 21 per cent between 2000 and 2023, driven largely by human-induced climate change.
Why Black Carbon is a serious threat:
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.
The study identifies the Indo-Gangetic Plain (IGP) — which spans parts of India, Nepal, and Bangladesh — as a major source of Black Carbon emissions affecting the Himalayan glaciers. This region contributes significantly due to activities like biomass burning, fossil fuel combustion, and open burning. The Eastern Himalayas are particularly impacted because of their proximity to these densely populated and industrially active areas.
The threat has been ignored for too long:
Other research, published earlier in Science Direct corroborates the findings now published by Climate Trends, indicating that India and Nepal together account for approximately 69% of Black Carbon emissions in the central Himalayas, with China also contributing notably, especially to the northern Tibetan Plateau.
The earlier joint study by experts from Nepal, India, China, and the US examined Black Carbon (BC) levels near Yala Glacier in the central Himalayas between October 2016 and September 2017. It found that:• Biomass burning was the largest source, accounting for 44% of annual BC, followed by fossil fuels.• BC deposition caused about 39% of glacier melting during the pre-monsoon season.• The pollution also reduced snow albedo (reflectivity) by up to 3.8%, intensifying melting.This highlights the significant local and regional responsibility in accelerating glacier loss and the urgency to cut emissions, especially from biomass and fossil fuels.
Given the transboundary nature of air pollution, the latest study by Climate Trends is alarming as it has highlighted how Black Carbon emissions have raised Himalayan snow surface temperatures by over 4°C in two decades, accelerating glacier melt. The study demands action by the stakeholders, governments and people alike, underscoring the need for regional cooperation among South Asian countries to effectively reduce black carbon emissions and mitigate their impact on the Himalayan cryosphere.
Kirti Pandey is a senior independent journalist.