Yeah, the "Global Warming" craziness is bullshit, but the common right wing talk about volcanoes is wrong. I got burned on this about a year ago arguing about how volcanoes produce so much carbon dioxide, etc. Fuck, the dumbasses who started this line as an argument against the global warming crowd either flat misunderstood maybe ONE report they happened to read or else didn't do any research at all and are only going by what someone told them. In other words, I don't know where they got this "data," but it is simply not supported by research and data that has been collected all over concerning volcanoes and carbon emission from them.
Don't use the volcano argument. It's not supported. Research the actual reports. Volcanoes don't put out the kind of carbon dioxide that you have heard from anti-global warming literature.