How does the carbon in a volcanic eruption come to be there in the first place?
The difference between natural events like volcanic eruptions and bushfires and human activity is that although carbon is put into the atmosphere it is reabsorbed down the line through carbon sinks like the ocean and plants.
When you start taking carbon that was trapped underground (i.e. oil) and releasing it into the atmosphere, compounded with the problem that we are not just not adding extra carbon sinks to compensate, but actively removing them, then you start to get issues when you look at the carbon balance in the end.
The earth will be unaffected in the end. But you can't say the same for the life that lives on it. The ocean absorbs carbon dioxide just as it does oxygen and other gases. When you dissolve carbon dioxide in water you get some carbonic acid. There is a complex equilibrium in ocean water that is easily disturbed.
I don't want to sound like a doped up hippie but there are more important things we should care about on the planet than the state of the economy. We went on without one for thousands of years. But in a fraction of that time we have, as one example, caused the bleaching of the Great Barrier Reef (it's happening as we speak). I shouldn't need to go on about why that's a bad thing, if you don't see why then I'm sorry, but you must have the intelligence of an eggplant as one poster so eloquently suggested. [As it happens, the reef is also highly at risk to changes in the ocean chemistry due to imbalance of CO2 concentrations in the atmosphere. Carbonic acid attacks coral and shells.]
You would think that on the whole, someone whose job depended on Australian tourism would care more about looking after the things people come here to see...