I want to take from another posting, because it was curious to me, and build upon it.
The USGOV reports 98% of the greenhouse gases come from fossil fuels and estimates that 6,008.6 million metric tons are dumped into the atmosphere annually as of November 2006 report. The US is believed to be the largest contributor worldwide to these gases.
These numbers came from: http://www.eia.doe.gov/oiaf/1605/ggrpt/carbon.html
The Earth's for the most part is a sphere with a diameter of est 12713 km +/- 75 km; a 0.5% variance. While the Atmosphere extends to 800km, the effective atmosphere (upto the ozone) is 50 km. Therefore, the math follows for computing the volumen of the atmosphere:
volume of a sphere = 4/3*Pi*r^3
Atmospheric volume = Volume to the ozone - the Earth's volume
volume of the atmosphere = 25,574,515,366.3 cubic km.
Density = pollutant tons / volume of atmosphere
The annual green house gases = 6,008.6 million metric tons.
This equates to a density of greenhouse gases emissions of .235 Metric tons per cubic km. (The original poster made an error not accounting for the word "million").
pollution density = .235 Metric tons per cubic km or 5.18E-7 lbs/cubic meter.
Now if I take this density and compare it to STP density of ordinary air, what percentage is attributed to pollutants?
STP density = 2.649 lbs per cubic meter.
Pollutant contribution to global atmospheric density = 1.96E-7 %
I would say this is way neglible and hardly enough to cause global warming. Remember its a Oxygen-Nitrogen atmosphere making up nearly 98% of the atmosphere. The amount of CO2 is estimated to be about 3.6E-2%. The percentage addition of pollutant CO2 is 5 orders of magnitude smaller or nearly 1 millionth of the natural amount present.
Okay folks, is that reasonable? Can that amount cause ice caps to crack? Can that amount ignite raging brush fires? Can that amount raise the earth's temperature not only one degree but several? I just don't see it.