One of the newest forms of rightist argument is the "that was debunked" tack - it seems that everything that a rightist believes that can be or is contradicted by facts wind up having been debunked but when asked for references to that "debunking" we are left high and dry or with links to opinion pieces, rightist blogs or claptrap science. Check out all of the "debunking" going on regarding the age of the earth and evolution.
Volcanic activity is "noise" or artifact in calculations it is not an ongoing, non-"natural" set of events that continualy pour carbon which was sequestered over millions of years back into an atmosphere in a matter of hundreds. Remember that.
ginja's post is confusing, the short of it is this, volcanic activity produces about 200 million tons of carbon per year, man produceds carbon at a rate of 26.8 billion tones.
your claim that we produce only a small percentage of volcanic activity has been "debunked"
http://hvo.wr.usgs.gov/volcanowatch/archive/2007/07_02_15.html