The ratio of black carbon to sulphate seems to have a big influence on global warming, as a study done by Greg Carmichael, from the University of Iowa, demonstrates.
Black carbons are emitted from diesel exhausts and burned biomass and are considered an environmental and health hazard all over the world. Besides the fact that they favor global dimming, black carbons also attract heat.
The team took samples of air at different altitudes at Cheju Island in South Korea: between 100 and 15,000 feet above the ground, using an unmanned aircraft (UAV). “These results had been indicated by theory but not verified by observations before this work,” Carmichael said.
“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.”
All the samples indicated that the amount of absorbed sunlight increased with the ratio between black carbon and sulphate. Black carbon plumes from fossil fuels attracted some 100 times more heat than the plumes that came from burning biomass.
The same researchers stated back in 2008 that black carbon soot originated from diesel exhausts and cooking fires are more important to global warming than carbon dioxide, at least in some parts of the world.