Black carbon

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Black carbon is a much larger cause of climate change than previously assessed; about twice previous estimates, and 2/3 the effect of CO2

January 16, 2013

Schematic overview of the primary black-carbon emission sources and the processes that control the distribution of black carbon in the atmosphere and determine its role in the climate system. Source: Bond et al. Click to enlarge.

Black carbon (BC) is the second largest man-made contributor to global warming and its influence on climate has been greatly underestimated, according to the first quantitative and comprehensive analysis of this pollutant’s climate impact.

The direct influence of black carbon, or soot, on warming the climate could be about twice previous estimates, according to an in-depth open-access study by an international team of 31 authors published in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union. Accounting for all of the ways black carbon can affect climate, it is believed to have a warming effect of about 1.1 Watts per square meter (W/m²), or approximately two-thirds of the effect of the largest man-made contributor to global warming—carbon dioxide.

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New inventory of black carbon emissions from China finds 2007 levels higher than previously reported

July 08, 2012

BC emission map of China at 0.1° × 0.1° for year 2007. East and West China are separated by a dashed line from Qiqihar, Yinchuan, to Kunming. Major emission areas are marked. Credit: ACS, Wang et al. Click to enlarge.

A new black carbon (BC) emissions inventory from China found BC emissions levels in 2007 of 1,957 Gg BC—higher than reported in earlier studies. The inventory also forecasts that BC emissions in China in 2050 will be 920–2,183 Gg/yr under various scenarios, with the industrial and transportation sectors standing to benefit the most from technological improvements. The paper by researchers from Peking University and Environment Canada appears in the ACS journal Environmental Science & Technology.

Black carbon is released into the atmosphere via incomplete combustion of carbonaceous fuel and is of major concern because of the impact on climate systems. BC emissions from Asia have been identified as a major cause of changing monsoon, the occurrence of the atmospheric brown cloud, and the retreat of Tibetan glaciers, in addition to impacting global temperature rise. (Earlier post.) Asia contributes more than half of global anthropogenic BC emissions and China is the largest emitter, according to the researchers.

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EPA report to Congress finds a strong scientific and technical foundation for mitigating black carbon emissions

April 02, 2012

Key policy-relevant scientific uncertainties related to BC. Source: EPA. Click to enlarge.

The US Environmental Protection Agency (EPA) has submitted its final Report to Congress on Black Carbon, in response to an October 2009 request from Congress to advance efforts to understand the role of black carbon (BC) in climate change.

The EPA report concluded that, despite some remaining uncertainties about BC that require further research (such as the sign—i.e., positive or negative—and magnitude of net climate forcing from BC emissions), currently available scientific and technical information provides a strong foundation for making mitigation decisions to achieve lasting benefits for public health, the environment, and climate.

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