CO2 is one of the three major volcanic gasses. (the others are SO2 and H2O)
Pu`u O`o, located on the Big Island (about 30 miles from CO2 observatory) has been “degassing” constantly since January, 1983. That is 24 years of nonstop eruption. The VOG (volcanic smog) is very similar to the air in Los Angeles, CA. People Kona side complain about VOG all the time, the trade winds carry it to Kona and then from Kona upslope to...Mauna Loa.
Today 12-4-07 the Kona winds are blowing and the VOG is all over the Hilo side covering Hilo town with a thick haze.
Take a look at the list of CO2 increase measurements and compare those before 1983 to those after 1983. There is a clear difference.
The Mauna Loa observatory claims that they are far from a pollution source are nonsense.
Alos CO2 constantly seeps upward through the rocks of volcanic cones such as Mauna Loa. This kills root systems keeping the upper slopes barren.
"Down slope winds sometimes transport these emissions to the observatory, where they are detected as a "noisy" increase above smooth baseline levels for some gases. A volcanic component can be estimated by taking the difference in concentration between periods when the plume is present and periods immediately before and after that exhibit baseline conditions."
and
"The CO2 emission rate follows a very predictable exponentially decreasing trend which is established after each eruption. The slope of these trends have been different for each eruption. Current concentrations of volcanic CO2 (2006) are at their lowest levels since the record began in 1958."