Black Carbon

Subject – Environment

Context – ‘Rising mercury is making Nepal glaciers vulnerable’

Concept –

Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms.
It is formed through the incomplete combustion of fossil fuels, biofuel, and biomass, and is one of the main types of particle in both anthropogenic and naturally occurring soot.
Black carbon causes human morbidity and premature mortality.
In climatology, black carbon is a climate forcing agent contributing to global warming. Black carbon warms the Earth by absorbing sunlight and heating the atmosphere and by reducing albedo when deposited on snow and ice (direct effects) and indirectly by interaction with clouds.
Black carbon stays in the atmosphere for only several days to weeks, whereas potent greenhouse gases have longer lifecyles, for example, carbon dioxide (CO2) has an atmospheric lifetime of more than 100 years.
- The IPCC and other climate researchers have posited that reducing black carbon is one of the easiest ways to slow down short term global warming.
The term black carbon is also used in soil sciences and geology, referring either to deposited atmospheric black carbon or to directly incorporated black carbon from vegetation fires.
- Especially in the tropics, black carbon in soils significantly contributes to fertility as it is able to absorb important plant nutrients.

Key Figures

460-1,500x	4–12 days	6.6 million tonnes	51%
Black carbon has a warming impact on climate 460-1,500 times stronger than CO₂ per unit of mass	The average atmospheric lifetime of black carbon particles is 4-12 days	About 6.6 million tonnes of black carbon were emitted in 2015	Household cooking and heating account for 51% of global black carbon emissions