Context: Black carbon concentrations near the Gangotri glacier rose 400 times in summer due to forest fires and stubble burning from agricultural waste, and triggered glacial melt, says a study by scientists at the Wadia Institute of Himalayan Geology (WIHG).

• India is the second largest emitter of black carbon in the world, with emissions expected to increase dramatically in the coming decades, says an April 2019 study in the journal Atmospheric Research, with the Indo Gangetic plains said to be the largest contributor.
• Black carbon absorbs solar energy and warms the atmosphere. When it falls to earth with precipitation, it darkens the surface of snow and ice, reducing their albedo (the reflecting power of a surface), warming the snow, and hastening melting.
• Scientists have been monitoring black carbon through two weather stations on way to Gangotri glaciers - namely Chirbasa station at a height of 3,600 m, and Bhojbasa station at a height of 3,800 m - for the last few years.
• Wadia Institute of Himalayan Geology (WIHG) is an autonomous institution under the Department of Science & Technology. It is headquartered in Dehradun (Uttrakhand).

Reasons for Increase in Black Carbon Concentration in Summer Season

• Period from April to June shows remarkable increase in black carbon concentration primarily due to direct and indirect activities related to tourism.
• Also, forest fires contribute to increasing black carbon concentration. According to the Forest Survey of India, the forest fire activity is generally reported in Uttarakhand from February to June, with a peak in fire incidences in May and June.
• Besides man made, other reasons for forest fires in the state include lightning, friction of falling rocks and monkeys accidentally throwing stones that create sparks leading to forest fires.
• Over 44,554 hectares of forest area has been damaged in forest fires in Uttarakhand since its formation in 2000.
• The lowest black carbon concentration has been recorded during August followed by December, likely due to the absence of tourist activities and forest fire incidences during these months.

Local Sources contributed to Black Carbon: Forest fires, domestic and commercial fuel wood burning, seasonal burning of crop residue and developmental activities.Pollution from local, regional and global sources that accumulate over the Himalayan region and increase the concentration of black carbon.

Possible Impact 

• Black materials absorb more light and emit infra-red radiation which increases the temperature. So, when there is an increase in black carbon in the higher Himalayas, it will contribute to faster melting of the Himalayan glaciers.
• In the longer run, the changes in the atmospheric composition of the high Himalayan will affect the weather pattern (such as rain and snow precipitation patterns), and accordingly natural resources and socio-economic activities of Himalayan communities.

Road ahead

• For the government the most significant aspect was the link with glaciers. "There are many quacks in glacier science. Some of them have been exposed. There is complete difference in behaviour of Himalayan glaciers and arctic glaciers which need to be studied and need to establish our own scientific capacity to understand this change.
• The Black Carbon (BC) aerosols contribute significantly towards global warming due to its light-absorbing nature. Their presence in the eco-sensitive zone, such as the Himalayan glacier valleys, is a matter of serious concern and needs to be meticulously monitored.