But as far as greenhouse gases go, CO2 is fungible -- it doesn't matter whether a ton comes from forest fires or from fossil fuels it has the same 'insulating' effect.
I don't see why the distinction is important?
In the short term they are going to act the same. So they will have an effect. What /how much of an effect I don't know - ask a climatologist? There will also be effects from all the particulate matter in the higher atmosphere. There will be effects from all the toxins from the smoke - it isn't just our lungs that are going to be affected. Also, changes in climate (and possible soil loss from erosion) means the trees holding that carbon out of circulation may not be replaced, so that carbon is now in the atmosphere for a lot longer. The article Deborah posted is very sobering, because we are also getting hotter, and in many places dryer. And it may well be that Canadian forest fires are adding as much CO
2 to the air as Canadian human production of CO
2. We've been having big fires for a good while now - think of the fires in BC and Alberta over the last 20 years. I haven't seen numbers, but someone must have them.
The distinction is that the carbon in trees/grass/etc. is part of the active circulating carbon cycle. It gets tied up for a while (up to a few thousand years in very old trees and humic acids in soil and sediments in lakes) and then goes back to the atmosphere. Some of the atmospheric carbon will be lost to sediment which will eventually turn into rock, but carbon from weathering and volcanoes will replace it. In the short term (without us) CO
2 is fairly stable, in the long run, when we get massive volcanic activity the CO
2 levels do change. Long run means geological time, not human time.
The thing about fossil fuels is that the carbon in them hasn't been in circulation for a long long time - many many millions of years. So it gets added into the regular carbon cycle as new carbon. It's as if we had thousands of volcanoes all spewing out CO
2 at once. Or think about currency - if banks keep the same amount in circulation things are pretty steady. If they start printing a lot of new currency so the supply grows the end result is runaway inflation (I think? I am not an economist). So we have added CO
2 from fossil fuels as background increase and then the fires add an extra amount of CO
2 that would be part of natural fluctuations if we weren't adding the extra from fossil fuels. (Sorry for the run-on sentence).
So yes, the added CO
2 from forest fires is a big immediate concern. This is not new - climate scientists and ecologists have been worrying about it since the major burning in the Amazon started. And that was human activity. Maybe we are noticing it more because these are fires that we didn't start on purpose? But from an atmospheric viewpoint it doesn't matter whether the forest is burning because people are clearing land for agriculture, or because there are out of control wildfires, it is all organic carbon being converted to atmospheric carbon.