[CodeToad]

“If mankind had never burned any coal, oil or natural gas, atmospheric CO2 levels would only be 30 to 50 ppmv lower than the current ~385 ppmv”

Got any proof of that? Seems like a “reasonable” statement to make, but “reasonable” isn’t scientific nor a fact.

[Talisker]

Got any proof of that? Seems like a “reasonable” statement to make, but “reasonable” isn’t scientific nor a fact.

The linked article is an extensive explanatory analysis of a paper published in the American Geophysical Union journal, Geophysical Research Letters.

[katana]

Frankly, considering all the myriad sources of this molecule upon which all life on Earth depends, and that its percentage of the atmosphere is presently far lower than in the geologic past, estimating the contribution by all puny human activities at ten percent is probably a monumental over-statement. Per one of my favorite lines of dialog from O' Brother Where Art Thou, "That don't make NO SENSE!"

[odawg]

from Wikipedia:

Carbon dioxide (CO2) is an important trace gas in Earth’s atmosphere currently constituting about 0.04% (400 parts per million) of the atmosphere.

Note: FOUR HUNDRED PARTS PER MILLION!!!!!!!!!!!

According to Obama and Prince Charles, that is enough to turn the earth into Mars.