Black Carbon: What Even Is It?

by Mia de Castro

September 7, 2020

Black carbon is an awful perpetuator of climate change that is rarely discussed, despite its threat to our health. Black carbon comes from the incomplete combustion of fuels like wood, fossil fuels, or others. Complete combustion would theoretically result in only carbon dioxide (CO2) produced, but this is not possible (yet we are still capable of trapping the byproducts to prevent their spread and harmful health effects). Instead, carbon monoxide, organic carbon, and black carbon are all formed as byproducts in the process, creating what we know as soot.

Household heating and cooking is responsible for about 58% of black carbon emissions, which might be shocking since large industries are usually more responsible for pollution than the average individual. However, modern heating systems and cookstoves are not responsible for this pollution. Biomass cookstoves that burn wood, coal, or crop residue and are heavily used in less developed countries are responsible for this percentage. Other sources include combustion of diesel and coal, as well as forest fires. International, specifically cross-Arctic, shipping also plays a role, yet its impact is difficult to quantify as there are few regulations on black carbon for international shipping.

Although black carbon is short-lived, remaining in the atmosphere for only 4-12 days, it has very harmful impacts on the earth. It is around 460 to 1200 times more potent than CO2 (per unit of mass). Black carbon absorbs solar radiation and converts it to heat, thus warming the atmosphere. It can also change rainfall patterns that disturb vegetation and other wildlife. Moreover, when black carbon settles on snow or ice, it inhibits the snow’s ability to reflect light. This causes the snow to absorb more heat, and it melts away, which poses a large threat to the polar ice caps. One study found that black carbon may be responsible for more than 30 percent of warming in the Arctic. This is especially concerning because the polar ice caps and other colder regions are essential to slowing the process of global warming, and their melting also raises sea levels.

Black carbon also comes with numerous health problems. Due to their small size (about 2.5 micrometers in diameter), black carbon and other particulate matter in air pollution are able to penetrate deep into our lungs and enter our bloodstream. These particles are known to cause multiple cardiorespiratory problems among other health risks. An estimated 3 million premature deaths occur annually worldwide due to outdoor air pollution.

Luckily, black carbon has a relatively more direct solution than those of other pollutants and GHGs. Because of its short-lived nature, the reduction of black carbon in the atmosphere would have virtually immediate positive impacts on our atmosphere and climate change rates overall.

Although more research is definitely necessary, decreasing the amount of diesel-powered vehicles on the road and implementing black carbon filters/capturing systems in vehicles would prevent a lot of our output of black carbon in the developed world. In developing countries, like India and China, which have a high black carbon output, diesel vehicles should also be limited, but switching to cleaner heating and cooking systems would arguably be more impactful. Ultimately, developing countries need to create more restrictions on air pollution to lower their output.

Yet, our individual impact can also be broken down to limit our black carbon footprint. The lack of air pollution regulations in China allows for more diesel use and more emission of black carbon. In Hong Kong, around 37 percent of all particulate matter pollution is attributed to marine emission. Because China is a leading country in shipping, especially international shipping by cargo ships, we could be indirectly contributing to the emission of black carbon. In essence, we should be limiting our consumption from manufacturers in China to reduce our personal carbon footprints.

There is considerable research to be done on black carbon, and the general public should be more aware of it for both their own health and that of the planet. Creating more regulations on its output would result in immense benefits for us and the environment.