Soot Could Be Twice as Dangerous as Estimated

Journal of Geophysical Research: Atmospheres.

Led by the International Global Atmospheric Chemistry Project, the authors of “Bounding the role of black carbon in the climate system: A scientific assessment” synthesized existing research and estimated effects with climate models and field observations over the course of four years. They concluded that the global warming contribution of black carbon has been greatly underestimated and could be twice that of previous estimates, such as the one in the 2007 Intergovernmental Panel on Climate Change Assessment. At about 1.1 watts per square meter, black carbon has approximately two-thirds the warming effect of carbon dioxide—making it the second-largest human contribution to climate change.

The authors note that black carbon’s warming effect is exacerbated by co-emissions from some of its primary sources, including diesel engines and household wood and coal fires, making them an urgent target for reducing emissions. Black carbon is a short-lived pollutant in the atmosphere but can darken the surface of snow and ice and increase melting. It is also known to be harmful to respiratory and cardiovascular health.