Does Volcanic Activity Produce More CO2 than Man?

"In 1991, the volcanic eruption at Mount Pinatubo in the Philippines put more carbon dioxide (CO2) into the atmosphere than did the whole human race during the most recent century of the industrial era."  A quote from Al Lowi, Jr., in a 2007 article published in Lew Rockwell  "Warming or Cooling? You Be the Judge"  Source: http://www.lewrockwell.com/orig5/lowi5.html
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When I asked Al Lowi to send back-up for this stunning quote he replied with the following:

From Alvin Lowi, Jr;
You are not the first to question the Pinatubo statement I made (you quoted) in that article. I certainly stirred up a controversy, which I confess I have not been able to settle even with the help of some geologists and volcanists. I tried to qualify it in a sequel to the paper you cited: http://www.lewrockwell.com/orig5/lowi6.html

The more I dig into the volcanic origin of atmospheric CO2, the more uncertainty I find surrounding the subject. In truth, the volcanic contribution to the Earth’s atmospheric CO2 inventory is still in substantial doubt. The USGS Hawaii article you cited in your later e-mail does not settle the issue. Submarine flows from faults, fissures and craters are yet to be determined with any confidence. All we know is that there is more submarine that surface eruption and the latter is highly variable and difficult to measure even in plain sight. Determining the atmospheric CO2 of volcanic origin is a daunting challenge not only because the vents are hidden but also because of the complex gas exchange relationship considering the oceans as an intermediate phase barrier. There is an equilibrium process at play the magnitude of which is staggering, as indicated here: http://www.globalco2equivalent.com/  and here: http://robouden.fatcow.com/globalco2equivalent/wp-content/uploads/2008/12/co2-presentation-slide-japanese0123.pdf 

Unfortunately, the volcanic contribution is neglected in this presentation for lack of information.

Fortunately, we know from physics that CO2 is a weak greenhouse gas, and also that the greenhouse effect has but a weak influence in the Global climate. Estimated global temperatures correlate with atmospheric CO2 concentration such that the latter appears to be driven by the former rather than the other way around as is most commonly believed. If you would like some references on this finding, let me know.

Actually, water is far and away the most important greenhouse gas, both in atmospheric concentration and strength of radiative interchange. But water also condenses to form clouds (not gas but liquid), the particles of which reflect and scatter incident sunlight before any greenhouse effects can occur. While such antecedent effects predominate in climate formation, they are infamously neglected in the computerized models that feed official opinion on the climate.

Sincerely, Al