Yeh, volcanoes are always a good fall back position the spinners.
Not important for what's going on, tho...
One point that is also worth making is that although volcanoes release some CO2 into the atmosphere, this is completely negligable compared to anthropogenic emissions (about 0.15 Gt/year of carbon, compared to about 7 Gt/year of human related sources) . However, over very long times scales (millions of years), variations in vulcanism are important for the eventual balance of the carbon cycle, and may have helped kick the planet out of a 'Snowball Earth' state in the Neo-proterozoic 750 million years ago.
realclimate.org
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And you're a scientist, right? You know that when there is more C02 in the air, it encourages plant growth.
Growth, not nutrition...
In a world changed by global warming, crops may grow more abundantly, but be unable to nourish us.
Humanity is on the threshold of a century of extraordinary bounty, courtesy of global climate change. That's the opinion of Robert Balling, former scientific adviser to the Greening Earth Society, a lobbying arm of the power industry founded by the Western Fuels Association. In a world where atmospheric carbon dioxide levels soar from the burning of fossil fuels, he says, "crops will grow faster, larger, more water-use efficient, and more resistant to stress." Quoting study after study, he invokes visions of massive melon yields, heftier potatoes, and "pumped-up pastureland." Bumper crops of wheat and rice, he says, will benefit the world's farmers and the hungry.
Balling's assertions are backed by solid science: Gaseous CO2 fertilization does cause remarkable growth spurts in many plants, and could create a greener planet with beefier tomatoes and faster-growing, bigger trees. But there's a catch: The insects, mammals, and impoverished people in developing countries who feed on this bounty may end up malnourished, or even starving.
A small but growing body of research is finding that elevated levels of atmospheric carbon dioxide, while increasing crop yield, decrease the nutritional value of plants.
alternet.org
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Then there is this, which won't happen @ atmospheric levels, but does in the body... I personally haven't seen it happen since Sun night.
All true, but the subjective distress is almost entirely caused by
the high CO2. Humans don't have good hypoxia sensors, and people have
walked into nitrogen filled rooms and died, before they even realized
there was anything wrong. You can breathe into a closed circuit which
takes out the CO2 until you pass out from hypoxia, without much
discomfort at all. On the other hand, in a submarine or someplace
where CO2 is building up but there's plenty of oxygen, it's intensely
uncomfortable, and feels like dying. So does breathing that 5% CO2 95%
O2 medical mix they treat CO victims with.
And when the CO2 hits about 7% to 10% of your ambient air, you DO
die. Even if the rest is O2. It's CO2 narcosis, and it shuts you
down. 5% CO2 is about 40 Torr, your normal blood level. So if you
breath that, you go up to 80 Torr, enough to black you out unless you
hyperventilate. Double your minute volume and you can get down to 60
Torr, but you feel crumby. At 10% there's no way to keep below about
90 Torr, and (unless you're a chronic COPD patient who's used to high
CO2s and has a high bicarb and other compensatory mechanisms) you black
out. Then quit hyperventilating. Then quit breathing entirely.
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