Black Carbon Emissions: Impacts and Mitigation
What is black carbon?
Black carbon (BC), a product of incomplete combustion of coal, diesel, biofuels, and biomass, is “the
most strongly light-absorbing component of particulate matter (PM)”1. It can be defined as “a solid form
of mostly pure carbon that absorbs solar radiation at all wavelengths”. BC is the most effective form of
PM at absorbing solar energy and is a major component of soot, which is impure carbon particles that also
contain organic carbon. “BC is emitted directly into the atmosphere in the form of fine particles (PM2.5)”.
Initial analysis indicates that Russia contributes about 7% of BC emissions globally, and natural fires,
residential, transport, and industry energy use appear to be main sources of BC emissions in Russia. In
the Russian Arctic, mobile and stationary engines are among the largest sources BC emissions and
substantial mitigation opportunities exist.
Impacts of black carbon on public health, environment, and climate
BC, as part of PM2.5, has “adverse impacts on human health, ecosystems, and visibility”. Short-term and
long-term exposures to PM2.5 are associated with respiratory and cardiovascular diseases, as well as
premature death. PM2.5, including BC, is also linked to reduced crop yields and damage to materials and
buildings. BC particles can penetrate into the human body through the lungs with inhalation, through the
gastrointestinal tract with water and food contact, and through skin and mucosa. In a study conducted by
the Russian Academy of Sciences, PM10 emissions are positively associated with an increase in nonaccidental deaths as well as mortality due to ischemic heart disease and cerebrovascular diseases in
Moscow between 2003 and 2005.
BC influences climate in three ways: direct effect, snow albedo effect, and cloud interactions. First, BC
contributes to warming of the atmosphere by absorbing radiation at all wavelengths (direct effect).
Second, BC “deposited on snow and ice darkens the surface, reduces reflectivity and thus increases
absorption and melting” (snow albedo effect). Third, BC also interacts with clouds, which affects cloud
stability, precipitation, and reflectivity (cloud interaction effects). These influences—particularly the
snow albedo effect—also make the Arctic particularly vulnerable to BC emissions. A recent study
concluded that black carbon had a net climate forcing of +1.1 W m-2, making it the second most important
contributor to climate change after CO2. In addition, the climate effect may increase the likelihood of
extreme weather, such as the prolonged and extreme summer heat in Moscow in 2010, which appears to
correlate with high mortality during that period.
Mitigation strategies and climate, environmental, health, and economic benefits
BC is emitted with other particles and gases and depending on their composition, these emissions
mixtures can generate mixed effects on the climate. Therefore, it is important to consider the effects of
co-emitted particles and gases when evaluating mitigation options. For example, BC accounts for about
75% of particle emissions from mobile diesel engines, while particles emitted in biomass burning are
primarily organic carbon, which is generally more reflective than black carbon. The location of the
emissions is also important, since emissions reaching the Arctic snow and ice will tend to cause warming
regardless of composition due to the very light surface underneath.
Improving combustion and controlling direct PM2.5 emissions can help reduce BC emissions. Some
recommended mitigation options include improving energy efficiency to reduce demand from diesel
generators, improving the efficiency of diesel machines, increasing new engine standards, or enhancing
1
All direct quotes are from “EPA. (2012). Report to Congress on Black Carbon. Washington DC: U.S.
Environmental Protection Agency. Available at: http://www.epa.gov/blackcarbon/ .”
1
fuel standards to reduce emissions from mobile sources, and replacing or retrofitting industrial boilers and
diesel generators. BC has a short atmospheric lifetime, and the climate will respond quickly to BC
emission reductions, especially in sensitive regions like the Russian Arctic. In addition, strategies to
reduce BC emissions normally reduce PM2.5 emissions as well, and this provides substantial public health,
environmental, and economic benefits. It is estimated that in the U.S. the benefits linked with reducing
PM2.5 emissions range from $290,000 to $1.2 million per ton PM2.5 in 2030; the estimated cost to achieve
such emissions reductions is much lower.
References
Bond, T. C., Streets, D. G., Yarber, K. F., Nelson, S. M., Woo, J.-H., & Klimont, Z. (2004). A
technology-based global inventory of black and organic carbon emissions from combustion. Journal of
Geophysical Research: Atmospheres, 109(D14), n/a-n/a. doi: 10.1029/2003jd003697. Available at:
http://onlinelibrary.wiley.com/doi/10.1029/2003JD003697/abstract .
Bond, T. C., Doherty, S. J., Fahey, D. W., Forster, P. M., Berntsen, T., DeAngelo, B. J., et al. (2013).
Bounding the role of black carbon in the climate system: A scientific assessment. Journal of Geophysical
Research: Atmospheres, n/a-n/a. DOI: 10.1002/jgrd.50171. Available at:
http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50171/abstract
EPA. (2012). Report to Congress on Black Carbon. Washington DC: U.S. Environmental Protection
Agency. Available at: http://www.epa.gov/blackcarbon/ .
Lamarque, J. F., Bond, T. C., Eyring, V., Granier, C., Heil, A., Klimont, Z., et al. (2010). Historical
(1850–2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols:
methodology and application. Atmos. Chem. Phys., 10(15), 7017-7039. Available at: http://www.atmoschem-phys.net/10/7017/2010/acp-10-7017-2010.html .
Menon, S., Hansen, J., Nazarenko, L., & Luo, Y. (2002). Climate effects of black carbon aerosols in
China and India. Science, 297(5590), 2250-2253. doi: 10.1126/science.1075159. Available at:
http://www.sciencemag.org/content/297/5590/2250 .
Panchenko, M. V., Kozlov, V. S., Polkin, V. V., Yausheva, E. P., Terpugova, S. A., Shmargunov, V. P.,
et al. (2012). Submicron aerosol and soot (BC). Presentation at the U.S.-Russia Inter-Academy Workshop
on Challenges of Black Carbon, co-hosted by the U.S. National Academies of Science and the Russian
Academy of Sciences, October 17-19, Moscow.
Popovicheva, O. (2012). Physico-chemical characterization of BC: impacts on climate and health.
Presentation at the U.S.-Russia Inter-Academy Workshop on Challenges of Black Carbon, co-hosted by
the U.S. National Academies of Science and the Russian Academy of Sciences, October 17-19, Moscow.
Revich, B., & Shaposnikov, D. (2012). Air pollution and heat wave related mortality in Moscow.
Presentation at the U.S.-Russia Inter-Academy Workshop on Challenges of Black Carbon, co-hosted by
the U.S. National Academies of Science and the Russian Academy of Sciences, October 17-19, Moscow.
Shevchenko, V. (2012). Distribution and sources of black carbon in the Russian Arctic Presentation at
the U.S.-Russia Inter-Academy Workshop on Challenges of Black Carbon, co-hosted by the U.S.
National Academies of Science and the Russian Academy of Sciences, October 17-19, Moscow.
Tolstikova, T. G. (2012). Present-day state of problem of toxic influence of “black carbon” upon living
systems. Possibilities of complex investigations in the Siberian Branch of RAS. Presentation at the U.S.Russia Inter-Academy Workshop on Challenges of Black Carbon, co-hosted by the U.S. National
Academies of Science and the Russian Academy of Sciences, October 17-19, Moscow.
2