The earth cools and warms, from the medival warming period (it really existed) to the following little iceage to warming thru 2000 and cooling (slightly) since. A lot of soot is manmade, and melts snow and clogs lungs.
Man is causing global warming via C02? No chance that 4% of a gas that occupies 5% of the atmosphere will have much effect.
thanx,
bill