This is a big one. The myth that volcanoes emit more CO2 than mankind is an old one, and old climate change myths die hard. The science concerning greenhouse gases and volcanoes is robust, yet a few stale papers continue to give the climate pretenders hope that it will all just be a bad dream (or whatever it is that they are hoping for.) The propaganda wielders continue to wave the defunct flags of their fallen scientists regardless of the magnitude of the rebuttals to their misguided science.
An article in EOS, the Transactions of the American Geophysical Union has looked at all of the available literature on the subject and found that what the non-believers believe is non-science. This article was written by a retired USGS volcanic gas physicist. The reality of volcanic emissions is that they generally emit no more greenhouse gas than U.S. states like Florida or Wisconsin. Compared to annual global GHG emissions, mankind emits 135 times more than a typical volcano. Even more revealing, the massive Siberian flood basalt events 250 million years ago released 0.5 percent the greenhouse gases of mankind. WE would need to see 700 Mount Pinatubo eruptions in one year to equal annual global GHG emissions. Mankind’s GHG emissions are so large that the only way that volcanoes could emit more is if there were a supervolcano eruption the size of the one that created the Yellowstone Caldera 2 million years ago–every year. these type of supervolcanos, the largest of their kind, only happen every 100,000 to 200,000 years.
Gerlach, Volcanoes vs. Anthropogenic Carbon, EOS, June 2011. http://www.agu.org/pubs/pdf/2011EO240001.pdf