WHAT IS BLACK CARBON ?

      HEADLINES:

Black carbon in High Asia can go down 23% if Subcontinent cuts emissions: Report

      WHY IN NEWS:

If South Asian countries implement all the current Black Carbon (BC) emission policies, the deposition of the pollutant can go down by 23 per cent, according to a new report released by the World Bank Group June 3.

SYLLABUS COVERED: GS 1 : 3 : Global Warming : Geography : Pollution

      ISSUE: 

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.
  • Several studies have demonstrated that measures to prevent black carbon emissions can reduce near-term warming of the climate, increase crop yields and prevent premature deaths.

KEY FIGURES

  • BC has a warming impact on climate 460-1,500 times stronger than CO2 per unit of mass

  • About 6.6 million tonnes of BC were emitted in 2015
  • Household cooking and heating account for 58% of global black carbon emissions
  • Once settled there, the BC reduces the light- and heat-reflection capacity of the snow, making it melt from the increase in temperature because of the absorbed heat energy. This accelerates the melting of snow and glaciers.
  • The report finds that BC deposition is responsible for as much as 50 per cent of the increase in glacier and snow melt worldwide.
  • According to recent scientific evidence, the glaciers in the Hindu Kush, Himalayan and Karakoram ranges are retreating at a rate of 0.3 metre per year in the western regions.

PRIMARY SOURCES OF BLACK CARBON EMISSIONS

  • Black carbon emissions have been decreasing over the past decades in many developed countries due to stricter air quality regulations.

  • As the result of open biomass burning and residential solid fuel combustion, Asia, Africa and Latin America contribute approximately 88% of global black carbon emissions.

WHAT IS BLACK CARBON ? | UPSC

SOURCES : CCACOALITION.ORG
  • Black carbon is always co-emitted with other particles and gases, some of which have a cooling effect on the climate.
  • The type and quantity of co-pollutants differs according to the source.
  • Sources that release a high ratio of warming to cooling pollutants represent the most promising targets for mitigation and achieving climate and health benefits in the near term.

CLIMATE IMPACTS

  • 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.

  • 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.

HEALTH IMPACTS

  • 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.

IMPACTS ON VEGETATION AND ECOSYSTEMS

  • 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.

      IASbhai WINDUP: 

SOLUTIONS

  • 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.

WHAT IS BLACK CARBON

  • The Coalition supports implementation of control measures that, if globally implemented by 2030, could reduce global black carbon emissions by as much as 80% (UNEP & WMO 2011).
  • Several of these emission reductions could be achieved with net cost savings. Adopting these measures would have major positive co-benefits for public health, especially in the developing world.
     SOURCES:   DownToEarth  | WHAT IS BLACK CARBON ? | UPSC

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