A researcher has discovered that black carbon which comes out as diesel engine exhaust and cooking fires can play a role in global warming.
Increasing the ratio of black carbon to sulphate in the atmosphere increases climate warming, suggests a study by University of Iowa professors Greg Carmichael, Karl Kammermeyer Professor of Chemical and Biochemical Engineering and colleagues.
They found that the amount of solar radiation absorbed increased as the black carbon to sulphate ratio rose.
Also, black carbon plumes from fossil fuels cause 100 percent more warming than plumes arising from biomass burning.
"There is currently great interest in developing strategies to reduce black carbon as it offers the opportunity to reduce air pollution and global warming at the same time," Nature quoted Carmichael as saying.
The team also said that coal and cow dung-fuelled cooking fires in China and India produce about one-third of black carbon.
The rest is largely due to diesel exhaust in Europe and other regions relying on diesel transport.
Also, soot and other forms of black carbon could equal up to 60 percent of the current global warming effect of carbon dioxide, the leading greenhouse gas.
The study is published in May 2008 in Nature Geoscience.