Rising snow and glacier melt puts almost 2 billion in South Asia at risk: report

The risks are aggravated by black carbon pollution, which could curb water supply from many rivers flowing through the Himalayan plains

The lives of nearly 2 billion people in South Asia are at risk as snow and glacier melt across the Himalayas accelerates, aggravated by black carbon pollution from burning biomass and fossil fuels and unsustainable farming, climate experts have warned.

Also known as soot, black carbon darkens snow surfaces and absorbs sunlight, causing it to act like a heat lamp and hasten melting. The fine particulate pollutant is typically released during the combustion of organic matter such as wood, crop residues and diesel.

With the largest ice reserves outside the polar regions, the Himalayas are the main source of water for many rivers flowing through the densely populated Indo-Gangetic plains. But this critical function is at risk from rising black carbon emissions and climate change.

The rivers nourish fertile agricultural zones across the Indian subcontinent – the world’s largest rice-exporting region. They have also been the source of growing geopolitical tensions, including between India and Pakistan.

Average snow surface temperatures in the Himalayan peaks have risen by more than four degrees Celsius, with black carbon a key contributor, according to a report by Delhi-based think tank Climate Trends released on Friday. It warned that the impact of these emissions was worsened by deforestation, crop burning and poor land management.

More than 40 per cent of India’s black carbon emissions come from biofuels, according to the report, with significant contributions from large states such as Madhya Pradesh and Maharashtra, where agricultural and forest fires are common. Emissions have also been recorded at high levels in the eastern Himalayas, particularly in Nepal.

“The Eastern Himalaya consistently exhibits the highest levels of black carbon, likely due to its proximity to densely populated and biomass-burning regions,” said Palak Baliyan, lead author of the study.

The impact of emissions together with climate change on Himalayan glaciers should be monitored carefully as studies had showed their ice volumes and potential water contribution might be less than previously assumed, it added.

The Himalayan and the Tibetan Plateau are among the most vulnerable regions in the world to climate change and pollution, according to experts. A rise of 1.5 degrees Celsius in global temperature translates into a rise of about 2.2 degrees in the Himalayas because of heat reflected from glacial ice, they say.

Himalayan glaciers like Chhota Shugri in the Indian state of Himachal Pradesh had borne the brunt of extreme heat events, losing up to two metres of ice, said Farooq Azam, a senior cryosphere specialist at the International Centre for Integrated Mountain Development, at the India Heat Summit held last week.

Since 2022, the glacial mass loss had been four times higher than normal, he said, adding that a similar phenomenon was observed in Europe, such as in Switzerland and Austria.

Last week, the collapse of the Swiss Birch glacier drew worldwide attention to the dangers faced by vulnerable communities from fragile ice. Television footage showed a huge cloud of ice and rubble hurtling down the mountainside into the hamlet of Blatten.

Asia was the world’s most disaster-hit region from climate and weather hazards in 2023, the UN said last year, mainly due to floods and storms. Among these disasters, Pakistan suffered extensive flooding in 2023 while the Indian village of Chamoly in Uttarakhand state was battered by an avalanche in 2021.

But Asian countries, particularly those with territory in the Himalayan region, lack the resources to monitor their vast glaciers as extensively as the Swiss, which even then still suffered from the incident at Blatten, according to analysts.

On the positive side, the Himalayan region could cool off within years and not decades by tackling black carbon emissions, which would typically stay in the earth’s atmosphere for just days or weeks, the Climate Trends report said.

“Reducing black carbon, especially from cookstoves, crop burning, and transport, can offer quick wins for climate and water security,” said Aarti Khosla, founder and director at Climate Trends. “It is also an effective way to achieve improved air health, which has been ailing the region for many years,” she added.

Participants at last week’s event also warned about the dangers of unrelenting heat rise across the region beyond the Himalayas.

Parts of India and China were vulnerable to extreme heat events if the global temperatures were to rise by 3 to 3.5 degree Celsius, said S.N. Tripathi, dean of the Kotak School of Sustainability at the Indian Institute of Technology, adding that the period for hot weather in the region could increase from 200 days to 300 days annually.

“It will be a catastrophe if that happens,” Tripathi said. Calling for artificial intelligence-based monitoring systems, he said such data collected could help highlight the need to check particulate emissions.