Stanford Professor Mark Jacobson urged the EPA to include black carbon in its endangerment finding, claiming that it can be the single largest factor to slowing Arctic warming if controlled now. Black carbon, or soot, is released from the burning of fossil fuels and has accounted for 12.5-15% of gross global warming. US black soot emissions account for more global warming than methane or nitrous oxide, which are in the endangerment finding, according to the reports cited by Professor Jacobson.