Impossible to say because CO2 fire extinguishers are a fiery Red Communist Conspiracy Hoax.
Chem Flunky made a nice attempt, but it is 11 doublings, not 10(perhaps that's why chose the nickname.)
so 11*1.2C is 13.2C with feedbacks. However, the assumption of 100% CO2 would affect all the feedbacks. There is no more water vapor to change things. What happens to the oxygen produced by the trees? Where did all the nitrogen go?
Hmm not sure that Chem Flunky's statement that a doubling from 500ppm will produce a 1C warming.
But if correct that means we can go up to 2000ppm without exceeding the 2C which generally agreed not a problem and maybe beneficial.
See this bar chart http://www.climategate.com/wp-content/up...
as your can see the first 20ppm produced half our warming, with future warming declining rapidly.
Basically any planets climate depends on the density of it's atmosphere and how much solar radiation it receives, the make up of it's gases only makes very minor alterations.
Alph 95% CO2 does not warm Mars up very much.
Lemme do some back-of-the-envelope math here.
For easier math, let's call it 500 ppm (or .05%). I think the direct warming from a doubling of CO2 is 1C. There are also feedbacks that would increase that, but let's just aim for a minimum here to start with.
To get from .05% to 100% by doubling:
.1, .2, .4, .8, 1.6, 3.2, 6.4, 12.8, 25.6, 51.2, and the next doubling takes us over 100, but we started a bit above the current level, so that's fine.
So, we're to around 10 doublings. Just from CO2 alone, that gets us to about 24C. For my fellow Americans, that's a change from a bit over 57F to a bit over 75F.
Now, let's add in feedbacks. The mid-range estimate seems to be 1C of feedbacks for every 1C of warming from other forcings. That takes our 24C up to 34C. Which is a bit over 93F, for the Americans.
So, by fairly conservative estimates, making the Earth's atmosphere 100% CO2 would take the Earth's average temperature from that of a brisk fall day to a hot summer day. And keep in mind, that's an average, including the poles and so forth. So it wouldn't surprise me if some places near the equator were very nearly hot enough to boil water, considering at present temperatures range from ~-80C (~-110F, 94C below the average) to ~70C (~160F, 56C above the average). The ice caps would almost certainly be completely melted, the planet would be unrecognizable, and we probably couldn't live on most of it even if we did have air.
edit: You're right, Mike, I added wrong. So we're at 25C from CO2 alone, and 36C including feedbacks. And you're right that imposing a 100% CO2 atmosphere would mess with some of the feedbacks, but it would also mess with a lot of other things. For example, the only way you could get an atmosphere at that temperature *without* water vapor would be if you removed all the surface water. I kind of was working under the assumption that, as such things are typically calculated (because of the higher variability of water vapor compared to other parts of the atmosphere), water vapor wasn't counted as part of the atmospheric percentage.
And, as the blurb on my profile page says, that's "flunky" as in "assistant", not "flunky" as in "failing".
does not matter. Life requires water and oxygen. with 100% CO2, we could not breathe or live.
At levels above 5% (50,000 PPM) , concentration CO2 is directly toxic
EDIT: KANO.. There is NO saturation as evidenced by Venus. There is no way the Earth would only warm up by a couple degrees, it already exceeded that in the paleoclimate record.
EDIT#2.. KANO.. nice try. I'm sure you know how thin the Mars atmosphere is. You are misleading or obfuscating.
I suspect it is not linear, and if you kept all the other green house gas including water vapor, the average might reach 20c. Perhaps 12 c if you only has carbon dioxide in Earth's atmosphere at 14.7 psi at sea level. Water vapor causes more temperature rise than 0.04% carbon dioxide.
Just look at Mars and adjust the same conditions according to earth's proximity to the sun and add in feedbacks from the water vapor.
It wouldn't matter because all animal life on the planet (including us) would be dead.
Right now it's about 14 C average.
