Global black carbon emissions, 1750-2022

Global emissions of anthropogenic black carbon increased by a factor of 10 from 1750 through the early 2000s. Biomass burning includes residential cooking and heating with wood and dried animal dung, agricultural field burning, and deforestation fires. When biomass is burned in inefficient cookstoves, open fires, or poorly ventilated areas (common in many households in developing regions), it often does not burn completely due to limited oxygen and lower temperatures, resulting in black carbon emissions.

The introduction of fossil fuel combustion, coal in the nineteenth century and oil in the twentieth century accelerated the release of black carbon. Coal and oil are carbon-rich materials, and when burned in inefficient furnaces, engines, and stoves they release black carbon. Diesel and heavy fuel oils used in highway, rail, and ship transportation have especially high emission rates.

Process emissions refer to the black carbon emitted from a specific industrial or chemical process rather than direct fuel combustion. Examples include metal smelting, refining, and processing; cement and lime production; chemical manufacturing; and pulp and paper production.