black carbon

Black Carbon

In a report titled “Glaciers of the Himalayas, Climate Change, Black Carbon and Regional Resilience”, the World Bank said that the  Black carbon (BC) deposits produced by human activity which accelerate the pace of glacier and snow melt in the Himalayan region can be sharply reduced through new, currently feasible policies by an additional 50% from current levels.

The research report from the WB covers the Himalaya, Karakoram and Hindu Kush (HKHK) mountain ranges, where, it says, glaciers are melting faster than the global average ice mass.

What is Black Carbon?

Black carbon, or soot, is part of fine particulate air pollution (PM2.5) and contributes to climate change.

Black carbon is formed by the incomplete combustion of fossil fuels, wood and other fuels. Complete combustion would turn all carbon in the fuel into carbon dioxide (CO2), but combustion is never complete and CO2, carbon monoxide, volatile organic compounds, and organic carbon and black carbon particles are all formed in the process. The complex mixture of particulate matter resulting from incomplete combustion is often referred to as soot.

Black carbon is a short-lived climate pollutant with a lifetime of only days to weeks after release in the atmosphere. During this short period of time, black carbon can have significant direct and indirect impacts on the climate, the cryosphere (snow and ice), agriculture and human health.





Black carbon (soot) deposited on ice

Black carbon is an important contributor to warming because it is very effective at absorbing light and heating its surroundings. Per unit of mass, black carbon has a warming impact on climate that is 460-1,500 times stronger than CO2.

When suspended in the atmosphere, black carbon contributes to warming by converting incoming solar radiation to heat. It also influences cloud formation and impacts regional circulation and rainfall patterns.

When deposited on ice and snow, black carbon and co-emitted particles reduce surface albedo (the ability to reflect sunlight) and heat the surface. The Arctic and glaciated regions such as the Himalayas are particularly vulnerable to melting as a result.


Black carbon and its co-pollutants are key components of fine particulate matter (PM2.5) air pollution, the leading environmental cause of poor health and premature deaths.

At 2.5 micrometres or smaller in diameter, these particles are, many times smaller than a grain of table salt, which allows them to penetrate into the deepest regions of the lungs and facilitate the transport of toxic compounds into the bloodstream.

PM2.5 has been linked to a number of health impacts including premature death in adults with heart and lung disease, strokes, heart attacks, chronic respiratory disease such as bronchitis, aggravated asthma and other cardio-respiratory symptoms. It is also responsible for premature deaths of children from acute lower respiratory infections such as pneumonia.

Each year, an estimated 7 million premature deaths are attributed to household and ambient (outdoor) PM2.5 air pollution.


Black carbon can affect the health of ecosystems in several ways: by depositing on plant leaves and increasing their temperature, dimming sunlight that reaches the earth, and modifying rainfall patterns.

Changing rain patterns can have far-reaching consequences for both ecosystems and human livelihoods, for example by disrupting monsoons, which are critical for agriculture in large parts of Asia and Africa.


Black carbon’s short atmospheric lifetime, combined with its strong warming potential, means that targeted strategies to reduce emissions can provide climate and health benefits within a relatively short period of time.


BLACK CARBON70% emissions reduction potential globally by 2030
  • Replace traditional cooking to clean burning modern fuel cookstoves
  • Replace traditional cooking and heating with clean-burning biomass stoves
  • Eliminate kerosene lamps
  • Replace lump coal with coal briquettes for cooking and heating
  • Replace wood stove and burners with pellet stoves and boilers
  • Modernize traditional brick kilns to vertical shaft brick kilns
  • Modernize coke ovens to recovery ovens
  • Use diesel particular filters for road and off-road vehicles
  • Fast transition to Euro VI/6 vehicles and soot-free buses and trucks
  • Eliminate high-emitting diesel vehicles
  • Ban open-field burning of agricultural waste
  • Capture and improve oil flaring and gas production
  • Ban open burning of municipal waste

World Bank Report Summary:

  • BC is a short-lived pollutant that is the second-largest contributor to warming the planet behind carbon dioxide (CO2).
  • Unlike other greenhouse gas emissions, BC is quickly washed out and can be eliminated from the atmosphere if emissions stop
  • Some of the ongoing policy measures to cut BC emissions are enhancing fuel efficiency standards for vehicles, phasing out diesel vehicles and promoting electric vehicles, accelerating the use of liquefied petroleum gas for cooking and through clean cookstove programmes, as well as upgrading brick kiln technologies
  • Specifically, in the Himalayas, reducing black carbon emissions from cookstoves, diesel engines, and open burning would have the greatest impact and could significantly reduce radiative forcing and help to maintain a greater portion of Himalayan glacier systems.
  • The Regional governments should to review policies on water management, with an emphasis on basin-based regulation and use of price signals for efficiency, careful planning and use of hydropower to reflect changes in water flows and availability, and increasing the efficiency of brick kilns through proven technologies.
  • Glacier melt produces flash floods, landslips, soil erosion, and glacial lake outburst floods (GLOF), and in the short run, the higher volumes of melt water could replace receding groundwater downstream. But in the long run, decreased water availability would aggravate water shortage.
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