Volcanoes and the World's Climate

For some reason, a number of climate change science deniers have latched on to the idea that human emissions of CO2 are insignificant and pale in comparison to what comes out of an erupting volcano.

It's a real pity for the state of a country's overall IQ that these people don't seem capable of even the teeniest bit of research.  If they were, they would very quickly find the following:

Under the heading "Volcanoes Can Affect the Earth's Climate", there are tidbits like this:

There is no question that very large volcanic eruptions can inject significant amounts of carbon dioxide into the atmosphere. The 1980 eruption of Mount St. Helens vented approximately 10 million tons of CO2into the atmosphere in only 9 hours. However, it currently takes humanity only 2.5 hours to put out the same amount. 

Depending on how many volcanoes are active, in general, volcanoes can throw off somewhere in the vicinity of 200 megatons of CO2 per year.  That's 200 million tons.

Human activity releases somewhere in the neighbourhood of 30 Gigatons.  That's 30 Billion tons. About 150 times as much as volcanoes.

To summarize: 

Volcanoes - perhaps 200 Million tons/year

Humans - perhaps 30 Billion tons/year.

Volcanoes also give off other stuff other than CO2, such as water vapour, various oxides of sulfur and lots or particulates.

The sulfur compounds and the particulates are well known to cause cooling of the earth.

In an article titled "How Volcanoes Influence Climate", are listed the various types of volcanic emissions and how they affect the climate.  And of course there is the increasing world temperature which doesn't match up with volcanic activity patterns.

There are many other reliable sources of this information.  Why is it so hard for some people to find it?