Originally Posted by Winged Wheeler

For perspective:

CO2 is about 0.04% of our atmosphere. It is classified as one of the trace gases. The mass of the atmosphere is in the peta ton (10^15) order of magnitude.

Human economic activity releases something like 30 giga tons (10^9) of CO2/year. The total CO2 released each year is just under 800 gigatons/year; this total includes human economic activity, animal respiration, organic decomposition, and other releases from soil, rocks, and the oceans. Thus, CO2 released by human economic activity is about 3% of total annual emissions from all sources.

Almost all (more than 98%) of the CO2 emitted into the atmosphere is reabsorbed each year. The CO2 left over is the source of the increasing atmospheric CO2 about which some people are concerned.

WW