It really doesn't matter if we're adding CO2 outside the natural process if the amount we are adding is insignificant compared to the total.  Thats why you HAVE to include natural additions to atmospheric CO2 when comparing against unnatural (human) additions.  If the total CO2 added by natural causes is 995, and the amount added by humans is 5, then its insignificant.  A rounding error.

 And of course if you remove all NATURAL cycles the human one is large.  We're about 1 of 2 or 3 factors outside of the natural cycle of things.

 On volcanoes:  I was under the impression that when Mt St. Helens errupted in the 80's that it spewed more greenhouse gasses and pollutants into the atmosphere than the entire human race since the industrial revolution.  Tell me again how significant our contributions are.  When 1 natural disaster outside of our control beats our emissions since we started emitting, how is global warming due to greenhouse gasses caused by humans again?

But if other sources of greenhouse gasses have been reasonably constant, and we're now adding to it, then it really makes no difference what level of natural greenhouse gasses were required to maintain previous temperature levels, human emmissions can still have just as much impact, regardless of the ratios between the two.

We only need a tiny % increase in the ammount of heat energy in the world to cause massive problems for humanity. Thinking 'Oh, less than 5% isn't that important' isn't really a sensible way of approaching things.

Well, you're wrong. There have been very reliable CO2 level measurements from the 60s and there's no significant spike to be seen in the data when St. Helens erupted, which would be expected if a major CO2 addition occured, because CO2 spreads relatively fast in the atmosphere. In fact, the pace of CO2 level rise has gotten faster in recent times although there have been very few major volcanic eruptions.

It is estimated that over 6 billion metric tons of anthropogenic CO2 is added annually to the atmosphere (2000). Source: http://www.eia.doe.gov/oiaf/1605/ggccebro/chapter1.html

To understand how big number billion is, a good way is to think billion in seconds. Whereas million seconds is about 11 days, billion seconds is about 31 years. That's how big number billion is. The 6 billion tons per year means over 16 million tons per day.

Weight is irrelevant. Its volume thats important, and comparing that volume to the total volume of the atmosphere, and the volume of CO2 added by natural causes.

And I didn't say CO2 for Mt. St. Helens, I said greenhouse gasses. Unless you are trying to say that CO2 is the only important greenhouse gas.

Ja seriously. "The total mass of the atmosphere is estimated to be some 5.5 quadrillion (55 followed by 14 zeros) tons (4.99 quadrillion metric tons)"

By your estimates, 1 billion seconds is 31 years, and 1 quadrillion seconds is 31709 years.

Do you agree that human is responsible for the 30% addition of CO2 in the atmosphere?*

I wanted to talk about CO2 because that is the only way we're able to keep this thread in sensible proportions. Otherwise it would blow up to like 22 pages and nobody's going to read it. But I guess that's your goal.

Well, If your last chapter isn't just for distraction, tell me how much and what greenhouse gases St. Helens released, what is the residence time and forcing qualities of those gases and how much sulfur particles etc. were released and what was the cooling effect of the particles.

*Volcanoes are basically the only non-anthropogenic way to add CO2 to the atmosphere from outside of the natural cycle. Other processes, like biological ones, only recycle the carbon in biosphere, they don't add it. So if you're saying volcanoes didin't add the CO2, then it's humans. Remember the isotope analysis?

But you do understand that CO2 is measured in parts per million and that human is responsible for the 30% addition of CO2 in the atmosphere? Do you also understand that the warming effect of CO2 and other greenhouse gases is logarithmic, which means that it's the percentage of addition that counts, not the quantity itself?

This site claims 3% of carbon dioxide emissions come from volcanic activity, with the other 97% coming from human activities. However, it uses a figure of 17.6 billion tons for the amount of CO2 added annually to the atmosphere. Yulegoat's source said it was only 6.1 billion. I'm not sure why the figures are so different, purhaps differing definitions. Anyway, using Yulegoat's figure, volcanic activity accounts for about 9% of total CO2 emissions.

This is a problem though, as long as we focus on CO₂ we will never see the big picture ...

We know that methane is about 22.5 times as potent of a greenhouse gas as carbon dioxide, and we have recently learned that worms produce a gas which is 290 times as potent of a greenhose gas as carbon dioxide. The last statistic I heard was that bugs like worms and termites outweighed humans, and with how potent this gas is a very small quantity of gas produced per worm could have a massive impact.

Your source adds land use to that number, which partly explains the difference. Forests, for example, are major CO2 absorbers. Here's an estimate of how much the deforestation in Amazon produces CO2: http://maps.grida.no/go/graphic/annual_deforestation_in_the_amazon_and_resulting_co2_emissions

It's about 600 million tons of CO2 per year, which is not adequate to explain the difference, but globally speaking, land use may well add up to several billion tons of CO2 per year.