Nature can and does cope with those minor injections of CO2, the dust is where volcanoes cause problems but all of these pale into insignificance against the billions of tonnes of CO2 mankind has vented through combustion of fossil fuels.
Except the amount of CO2 from geological processes is pretty much a WAG. Some of it relies on 'fingerprinting', ie looking at the isotope ratios of the carbon and assuming old carbon must have come from fossil fuels.. But then volcanic or natural methane seeps have the same fingerprint.
But the amount humans produce pale into insignificance against the amount produced naturally by stuff like soil bacteria, or simple organic decay.. Which can also be climate related, and why in the historical record, CO2 tends to follow warming. But when the effect precedes the cause, it gets harder to argue CO2 is the major causative factor.
But such is clmate science. Quantifying natural processes is challenging, so easier to ignore them and assume prior to 1950 or whenever, our climate was in perfect equilibrium.. Which means ignoring stuff like Ice Ages (especially little ones) and ongoing geological processes like isostatic rebound as we recover from those. Which is also why Global Warming is good news, ie NY won't be under a few kilometers of ice any time soon.