Saying something like 'volcanos are more responsible for CO2 in the atmosphere than man made causes' is true but misleading. Misleading in that the earths atmosphere works in cycles, it has been like this for millions of years. In the past century, and certainly the past two decades, CO2 output has been increased because of human causes. To argue that the output of CO2 by man is very small, hence a non-issue, is looking at it rather blindly given that quantity isn't always the defining factor. For instance even a little bit of magnesium, in the realms of parts per million, can destroy a lake.
hmm.. time to learn more. *goes article hunting*
heres more.
A widely accepted estimate of the amount of CO2 spewed into the atmosphere each year by normal volcanic activity (venting etc.) on land and at sea is 300 million metric tons. Sounds a lot, but human burning of fossil fuel is measured in tens of billions on metric tons per year. Anthropogenic CO2 emissions are around 100-150 times those of volcanoes.
But what about big eruptions? The largest recent one was Pinatubo in 1991. US geologists estimate that between 40 and 240 million metric tons of CO2 were spewed into the atmosphere by the volcano on the day of the eruption in June 1991. Again, it sounds a lot, but that's only somewhere between 1 and 7 day's worth of human fossil fuel burning.
Claims that a single volcano produces more CO2 than humans do in decades is not only wrong, it is ludicrously wrong.
well now. looks like things aren't black and white again.