Soot is the second largest man-made contributor to global warming, according to a comprehensive new study published in the Journal of Geophysical Research: Atmospheres.
The research effectively doubles the estimate of soot’s direct warming influence on climate. Soot is produced from the burning of diesel fuel, coal, charcoal, and wood.
“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, approximately two-thirds of the effect of the largest man made contributor to global warming – carbon dioxide,” said the American Geophysical Union, the publisher of the Journal of Geophysical Research: Atmospheres, in a statement.
Aerosol Black Carbon Optical Thickness. Courtesy of NASA.
The finding isn’t a surprise. A study published in 2008 also argued that soot’s climate impact was much higher than conventionally believed. As such, both the United States and the United Nations have programs that aim to reduce soot production. Reducing soot is seen as offering benefits beyond mitigating climate change — cutting particulate emissions improves air quality and helps reduce associated health problems.
The new study nonetheless strengthens the case for soot reduction initiatives. The authors argue for targeting emissions from diesel engines and wood and coal burning by households to have the most immediate cooling impact.
Since the early 20th century, Earth’s average surface temperature has increased by about 0.8 °C (1.4 °F), according to a NASA analysis released today. Carbon dioxide, soot, and methane emissions are the three largest anthropogenic contributors to climate change.
CITATION: T. C. Bond et al (2013). Bounding the role of black carbon in the climate system: A scientific assessment. Journal of Geophysical Research: Atmospheres 15 JAN 2013 07:30AM EST | DOI: 10.1002/jgrd.50171