Glaciers melting faster as black carbon heats up the Himalayas

The Himalayas are often called the 'Third Pole' because of their vast frozen reserves. For the past few years, these mountain ranges are facing rapid changes due to the direct impact of climate change on glaciers, one of the major sources of water. These changes can destabilise water supplies affecting nearly two billion people across South Asia.

Prioritising the significance of glaciers, the United Nations declared 2025 as the International Year of Glaciers, with an aim to raise global awareness and push for urgent action to preserve glaciers due to their critical role in sustaining life on earth. From this year onwards, March 21 has been marked as the World Day for Glaciers globally.

A recent study, ‘Impact of black carbon on Himalayan glaciers: a 23-year trends analysis’ examined satellite data from the NASA from 2000 to 2023 on the Himalayan glaciers to evaluate the impact of black carbon emissions on them. Black carbon is a short-lived climate pollutant and a major component of air pollution, contributing significantly to global warming. The study conducted by think tank, Climate Trends, shows that black carbon concentration in the region rose significantly between 2000 and 2019. The analysis showed that the emission levels were relative stable between 2019 and 2023, suggesting a possible plateau in emissions or a change in atmospheric conditions.

According to the study, 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 been experiencing higher snow surface temperature and lesser snow depth. The snow depth is reducing at a faster pace where black carbon deposition is more. Hence more black carbon means higher surface temperature, more snow melt and reduced snow depth. This scenario is not good for our planet.

“Glacier melt is accelerating, threatening freshwater resources, impacting nearly two billion people downstream in the Himalayan region. Glacier melt acceleration can disrupt long-term water storage, raises the risk of floods and droughts and alters the seasonal availability of water. The eventual decline in glacier mass will reduce water supplies, particularly during dry seasons. The Eastern Himalayas consistently exhibit the highest levels of black carbon, likely due to their proximity to densely populated and biomass-burning regions. Major sources contributing to black carbon emissions include biomass combustion, fossil fuel use, and open burning, particularly in the Indo-Gangetic Plains that act as a hotspot for emissions,” says Dr Palak Baliyan, lead author of the study.

This study includes references to other studies which throw more light on the subject. According to another study, biofuel combustion is the primary contributor to black carbon emissions in India, accounting for 42 per cent depositions, followed by open burning at 33 per cent, and fossil fuel combustion at 25 per cent, respectively

Similarly , yet another study reveals that the biomass-burning operations in the two major states of India, Madhya Pradesh and Maharashtra were the strongest, accounting for around 25 to 45 per cent of the total yearly fire counts reported across the country during the study phase of 1998 to 2009.

The Indo-Gangetic Plains across the states of Punjab, Haryana, Bihar and Uttar Pradesh are also considered one of the biggest sources of black carbon emissions. Eastern states of West Bengal, Meghalaya and Assam are among the other states with significant domestic biomass burning rates, mostly used for cooking and heating needs. These are findings of another study.

“Reducing black carbon emissions, especially from day-to-day sources like open cook-stoves, crop burning and transport, can offer rapid solutions for climate and water security. Policy recommendations to that effect in the Indo-Gangetic Plains can have an immediate effect on reducing black carbon emissions. It is also an effective way to achieve improved/better air quality, as this problem has been impacting the region for many years,” suggests Aarti Khosla, director, Climate Trends.

Dr Farooq Azam, senior cryosphere specialist, International Centre for Integrated Mountain Development, Nepal, speaking at the India Heat Summit 2025 in Delhi recently, highlighted the alarming glacier loss due to extreme heat. He cited 2022 as the worst year for global glacier mass balance, with Himalayan glaciers like Chhota Shigri Glacier, Lahaul and Spiti valley, Himachal Pradesh, losing up to two meters of ice. Early heatwaves exposed low-albedo ice, accelerating the melt. This ice reflects less sunlight back into space than typical snow or ice. Hence, it absorbs more solar energy, leading to faster melting.  “In 2024, we crossed the 1.5°C temperature threshold as compared to the pre-industrial level. Since 2022, the glacial mass loss is four times higher than the normal mass wastage. Similar estimates are observed in Switzerland and Austria as well. With more temperature, glaciers are shrinking and more heavy metals melting in the river water. Studies reported that the peak water level in the Brahmaputra river has been breached. In the Himalayan region, the increase in temperature is higher than the global mean,” Dr Azam added.

The recent collapse of the Birch Glacier in the Alps on May 28 this year is a stark reminder of how rapidly our glaciers are destabilising and the growing threat of climate-driven disasters. Air pollution is accelerating snowmelt in the Himalayas, but decisive human action can still protect the planet’s vanishing ice giants.

Professor Anjal Prakash, research director, Bharti Institute of Public Policy, Indian School of Business (ISB), Hyderabad, and the lead author for a special report on ‘Climate Change and Cities’ by UN Intergovernmental Panel on Climate Change, sums it up succinctly, “Reducing black carbon emissions offers a quick win for climate health, preserving precious water resources and safeguarding vulnerable communities downstream.”

— The writer is an independent environment journalist