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WHAT IS BLACK CARBON ?
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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.