August 23, 2010
A recently released study highlighted the contribution that soot has on global climate change.
Stanford researcher Mark Jacobson examined the effects of soot — black and brown particles that absorb solar radiation — from two types of sources: Fossil fuels — diesel, coal, gasoline, jet fuel — and from solid biofuels, such as wood, manure, dung and other biomass. He also focused in detail on the effects of soot on heating clouds, snow and ice.
What he found was that the combination of both types of soot is the second-leading cause of global warming after carbon dioxide and ahead of methane, an important greenhouse gas.
Soot from fossil fuels contains more black carbon which is highly efficient at absorbing solar radiation in the atmosphere, just like a black shirt on a sunny day. Black carbon converts sunlight to heat and radiates it back to the air around it. This is different from greenhouse gases, which primarily trap heat that rises from the Earth’s surface. Black carbon also can absorb light reflecting from Earth’s surface, which helps make it such a potent warming agent.
A summary of the results can be found here. The full study can be found here.
Since ethanol blended with gasoline and biodiesel blended with diesel emit less soot when burned than straight gasoline and diesel alone, this could be another way in which ethanol and biodiesel contribute to lessening the environmental effects of burning fossil fuels.