BBC: New research says that black carbon, or soot, is making a much larger contribution to global warming than previously recognised.
Scientists say that particles from diesel engines and wood burning could be having twice as much warming effect as assessed in past estimates.
They say it ranks second only to carbon dioxide as the most important climate warming agent.
The research has been published in the Journal of Geophysical Research-Atmospheres.
Black carbon aerosols have been known to...