[Gondring]

That 150x comes from this study which was done in 15 years ago in1992,

Terry Gerlach is the volcanologist cited. Here's a more recent article with commentary from him...

Compared to man-made sources, though, volcanoes' contribution to climate change is minuscule, Gerlach said.

Mount St. Helens produces between 500 and 1,000 tons a day of carbon dioxide, he estimates.

Nothstein, of the state energy office, says the Centralia coal plant puts out about 28,000 tons a day. Statewide, automobiles, industries, and residential and business heating systems emit nearly 10 times that amount.

On a global scale, the difference is even more dramatic, said Gerlach, who often gets calls from power-plant operators and oil-company executives who believe nature is just as responsible for global warming as man. His answer always disappoints them.

"I tell them the amounts don't even come close and I usually never hear from them again."

Worldwide, people and their activities pump 26 billion tons of carbon dioxide into the atmosphere, he said. The total from volcanoes is about 200 million tons a year — or less than 1 percent of the man-made emissions.

The point is that while Mt. St. Helens is the largest polluter in the state of Washington for sulfur dioxide, its carbon dioxide impact is miniscule.

[cogitator]

You know what's funny -- and you can look in my profile about this -- on geological timescales, CO2 volcanic emissions are a significant climate driver. Tectonism actually has a variable rate -- and if it speeds up or slows down, this affects uplift, erosion, sea level, shallow water carbonate deposition, and subduction of carbonate sediments into the magmatic upwelling zone (i.e., "Ring of Fire" currently). All of these factors affected atmospheric CO2 concentrations through paleoclimate history.

But now that man's involved, we're pumping it into the atmosphere a lot faster than volcanoes ever did, with the possible exception of flood basalt emplacements like the Deccan or Siberian.

[qam1]

I don't know where he got 26 billion tons of carbon dioxide, that's the highest I've ever heard, so it sounds like he's just pulling numbers out of his arse.

But I'm not arguing land based volcanoes produce more CO₂ than humans, all I said was that there's a hell of a lot of volcanic activity going on under the sea that as of now nobody can say how much CO₂ they are releasing. But factor in these recent discoveries and that 150x man vs volcano number will come down. How much? Well until more information comes in nobody can say, it may or may not exceed man's output. So while Conservatives shouldn't use it as an argument against AGW because they don't know, at the same time Liberals don't know either so they also can not say it is wrong at this time.