Diesel-burning big rigs

Well, this bit of news isn't going to make German automakers or truckmakers terribly happy. Following the connection between diesel fumes and cancer, scientists have found that the black particles created by burning fuels – i.e. black carbon or soot – do more to warm the earth than previously estimated, The New York Times reports, citing a study written by more than 30 scientists that was released this week.

In fact, the report, published in The Journal of Geophysical Research-Atmospheres, says black carbon contributes to global warming two to three times faster than what was previously estimated by the United Nations' Intergovernmental Panel on Climate Change in 2007. Only carbon dioxide is a bigger factor than soot when it comes to global warming. For instance, the scientists factored in issues such as black carbon falling on a glacier. This causes the glacier to absorb heat faster, so, naturally, the ice melts quicker. Not good.

The black carbon under study here is created by factors ranging from forest fires to, yes, the operation of diesel engines. German automakers have been promoting diesel as a way to reduce emissions through so-called "clean diesel" engines that burn cleaner and get better fuel economy than their gas-burning counterparts. The scientists stress that research on the global-warming effects of soot is in its early stages, so stay tuned.