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Bounding the role of black carbon in the climate system: A scientific assessment

  1. T. C. Bond1,*,
  2. S. J. Doherty2,
  3. D. W. Fahey3,
  4. P. M. Forster4,
  5. T. Berntsen5,
  6. B. J. DeAngelo6,
  7. M. G. Flanner7,
  8. S. Ghan8,
  9. B. Kärcher9,
  10. D. Koch10,
  11. S. Kinne11,
  12. Y. Kondo12,
  13. P. K. Quinn13,
  14. M. C. Sarofim6,
  15. M. G. Schultz14,
  16. M. Schulz15,
  17. C. Venkataraman16,
  18. H. Zhang17,
  19. S. Zhang18,
  20. N. Bellouin19,
  21. S. K. Guttikunda20,
  22. P. K. Hopke21,
  23. M. Z. Jacobson22,
  24. J. W. Kaiser23,24,25,
  25. Z. Klimont26,
  26. U. Lohmann27,
  27. J. P. Schwarz3,
  28. D. Shindell28,
  29. T. Storelvmo29,
  30. S. G. Warren30,
  31. C. S. Zender31

DOI: 10.1002/jgrd.50171

©2013. American Geophysical Union. All Rights Reserved.


Journal of Geophysical Research: Atmospheres

Accepted Article (Accepted, unedited articles published online and citable. The final edited and typeset version of record will appear in future.)

Additional Information(Show All)

Author InformationPublication History

Author Information

  1. 1

University of Illinois at Urbana-Champaign, Urbana, Illinois, USA

  1. 2

Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, Washington, USA

  1. 3

NOAA Earth System Research Laboratory, Boulder, Colorado, USA and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA

  1. 4

University of Leeds, Leeds, UK

  1. 5

Center for International Climate and Environmental Research-Oslo and Department of Geosciences, University of Oslo, Oslo, Norway

  1. 6

US Environmental Protection Agency, Washington, DC, USA

  1. 7

University of Michigan, Ann Arbor, Michigan, USA

  1. 8

Pacific Northwest National Laboratory, Richland, Washington, USA

  1. 9

Deutsches Zentrum für Luft- und Raumfahrt Oberpfaffenhofen, Wessling, Germany

  1. 10

US Department of Energy, Washington, DC, USA

  1. 11

Max Planck Institute, Hamburg, Germany

  1. 12

University of Tokyo, Tokyo, Japan

  1. 13

NOAA Pacific Marine Environment Laboratory, Seattle, Washington, USA

  1. 14

Forschungszentrum Jülich GmbH, Jülich, Germany

  1. 15

Norwegian Meteorological Institute, Oslo, Norway

  1. 16

Indian Institute of Technology, Bombay, India

  1. 17

China Meteorological Administration, Beijing, China

  1. 18

Peking University, Beijing, China

  1. 19

Met Office Hadley Centre, Exeter, UK

  1. 20

Division of Atmospheric Sciences, Desert Research Institute, Reno, Nevada, USA

  1. 21

Clarkson University, Potsdam, New York, USA

  1. 22

Stanford University, Stanford, California, USA

  1. 23

European Centre for Medium-range Weather Forecasts, Reading, UK

  1. 24

King’s College London, London, UK

  1. 25

Max Planck Institute for Chemistry, Mainz, Germany

  1. 26

International Institute for Applied System Analysis, Laxenburg, Austria

  1. 27

Eidgenössische Technische Hochschule Zürich, Zurich, Switzerland

  1. 28

NASA Goddard Institute for Space Studies, New York, New York, USA

  1. 29

Yale University, New Haven, Connecticut, USA

  1. 30

University of Washington, Seattle, Washington, USA

  1. 31

University of California, Irvine, California, USA

*Corresponding author: T. C. Bond, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. (

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/jgrd.50171

Publication History

  1. Accepted manuscript online: 15 JAN 2013 07:30AM EST
  2. Manuscript Accepted: 4 JAN 2013
  3. Manuscript Revised: 6 DEC 2012
  4. Manuscript Received: 26 MAR 2012


[1] Black carbon aerosol plays a unique and important role in Earth’s climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption, influence on liquid, mixed-phase, and ice clouds, and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related; namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr-1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models, and should be increased by a factor of almost three. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m-2 with 90% uncertainty bounds of (+0.08, +1.27) W m-2. Total direct forcing by all black carbon sources, without subtracting the pre-industrial background, is estimated as +0.88 (+0.17, +1.48) W m-2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m-2 with 90% uncertainty bounds of +0.17 to +2.1 W m-2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m-2, is the second most important human emission in terms of its climate-forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil-fuel and biofuel) have an industrial-era climate forcing of +0.22 (-0.50 to +1.08) W m-2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all black-carbon-rich sources becomes slightly negative (-0.06 W m-2 with 90% uncertainty bounds of -1.45 to +1.29 W m-2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.

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