The problem is that some people assume they know things that they don't know.
Let me demonstrate this.
Suppose 100 ppm of CO2 on planet Earth adds 1 C in global average temperature.
What does this actually mean?
It can only mean that most of this warming is warming nites and winter areas. What it does NOT mean is that most warming is added to daytime and particularly to warmest period of the day temperature.

If you have an environment which has no CO2 in it, and you going to add CO2 to it. And we still assuming that 100 ppm of CO2 added gives a 1 C increase:
Does each successive addition of 100 ppm add 1 C? If you add 1000 ppm do get addition of 10 C in global temperature?
How about if you add 10,000 ppm or 100,000 ppm. If Earth's atmosphere was 100% CO2 [or 1 Atm of CO2 in addition to other gases in our atmosphere]?

You can see the problem here, no?
If it was merely simple addition of 1 C per 100 ppm, Earth with 1 atm of CO2 would be hotter than Venus- and Venus recieves twice the Sunlight energy per sq meter as compared to Earth AND Venus rather having 1 atm of CO2 has over 90 atm of CO2.

So if 100 ppm of CO2 adds 1 C, then each successive addition MUST add less than 1 C. OR Each addition of 100 adds less than 1 C AND each successive of added CO2 adds less. OR there is just one other possiblity and that is you more or less get a straight addition until you near the point of getting a uniform nite time and day time [winter/summer] temperature, and after this point get significantly less added per 100 ppm.

Now, if I'm guessing right you prefer the last option. [I know it's tempting, but believe me it's a quagmire:]

Earth's atmosphere has:
"the present composition of the atmosphere is 79% nitrogen, 20% oxygen, and 1% other gases."
http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html
Or:
The Earth's atmosphere is 77% nitrogen, 21% oxygen, with traces of argon, carbon dioxide and water.
http://www.nineplanets.org/earth.html
Or:

"It contains roughly 78% nitrogen and 21% oxygen, with trace amounts of other gases such as water vapor."
http://en.wikipedia.org/wiki/Earth's_atmosphere

All are wrong but first one is closest.
Getting closer:
"Chemical Composition Today - Nitrogen (N2)- 78%, Oxygen (O2)- 21%, Carbon Dioxide (CO2) - 0.03 %, plus other miscellaneous gases (H2O for one)."
http://www.ux1.eiu.edu/~cfjps/1400/atmos_origin.html
But it goes on to say in a table:
Dry Atmosphere of: 78.08% nitrogen, 20.92% oxygen, .93% Argon, and .04 % CO2 [with a bunch of other trace gases less than CO2].
The fact it that mentions it is referring to the dry atmosphere makes this the most accurate. You don't measure water in the atmosphere because it varies daily/hourly/and from place to place. But there is a fair amount water in the atmosphere, roughly you could say there is 0-5%. BUT there is probably no place on Earth in which there is more CO2 than water in atmosphere- BUT roughly, .04 is zero [10 times this is amount is still roughly zero].

Let put it way, if you took all gases out of our atmosphere except CO2 there would less atmospheric pressure on Earth than on Mars. Quick freeze Mars and Earth, and you would get deeper CO2 snow on Mars than Earth.
Mars:
"Mars has a very thin atmosphere composed mostly of the tiny amount of remaining carbon dioxide (95.3%) plus nitrogen (2.7%), argon (1.6%) and traces of oxygen (0.15%) and water (0.03%). The average pressure on the surface of Mars is only about 7 millibars (less than 1% of Earth's), but it varies greatly with altitude from almost 9 millibars in the deepest basins to about 1 millibar at the top of Olympus Mons"
http://www.nineplanets.org/mars.html

On Earth: At sea level, the standard value of pressure is 1013.25 millibars. So Mars is slightly less than 1% of Earth atmosphere pressure and mostly CO2. So roughtly speaking the CO2 snow on Mars would about 20 times deeper. Or pertain to the point: 20 times more greenhouse CO2 gas to warm Mars as compared to Earth. [Mars is much smaller planet than Earth so it DOESN'T have 20 times the total volume of CO2 as in Earth's atmosphere. And Mars is far, far away from the Sun, so it recieves less than half of the solar radiation as Earth does. But it's CO2 doesn't help much terms keeping the nite warm:
"While the average temperature on Mars is about 218 K (-55 C, -67 F), Martian surface temperatures range widely from as little as 140 K (-133 C, -207 F) at the winter pole to almost 300 K (27 C, 80 F) on the day side during summer."
http://www.nineplanets.org/mars.html

"This image shows the nighttime (2AM) temperatures measured by the Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor wrapped on to a globe. The coldest temperatures (shown in purple) are -120C and the warmest temperatures (white) are -65C."
http://tes.asu.edu/webdata/may_temps.html

Oh, it better than the moon [with day a month long and zippo atmosphere: "Mean surface temperature (day) 107°C & Mean surface temperature (night) -153°C" ]
http://www.solarviews.com/eng/moon.htm

Ok. Take Earth and suck all the water, atmosphere, dirt, trees, ect off the planet. So all that's left is bare rock and vacuum. The temperature will be similar to the Moon- you have faster day and if you are mile or two underground- you wouldn't notice any temperature difference- but similar enough.
Now add all the nitrogen atmosphere back.
What happens?
You get vicious very nasty wind. 500 mph wind would probably be fairly common. Oh it would be cold, but the wind would be what you would worry about. Wind farms would do great if you make them able to withstand the wind.
Now, add your .04% CO2 to this. I don't think it's going to make much difference.
Add the dirt. Well, of course now you make even worse- forget about wind farming- anything will get sandblasted out of existance. But it would moderate the temperature, somewhat- if it's really windy the day would be dark as nite- it would like the dustbowl but more colder, more wind, and days would be generally darker.
Add the 21% oxygen and you can breathe- but not much else would change.
Add back the water and winds would reduce significantly and average temperature would rise significantly- plants and animals could live.

Start again from bare rock and vacuum.
Add the water first.
It's bit harder to fiqure out what would happen- in a vaccum you don't get a liquid water- liquid water boils and cools and freezes as result of the boiling. But if it warm enough you get an atmosphere of water [therefore could have liquid water].
Or say instead say you have everything, but remove 1/2 the water. Or say remove 90% of the water.
The oceans of our world store heat, move around heat, and trap most the heat from the Sun. Our oceans control our climate.