Lv 7
gcnp58 asked in EnvironmentGlobal Warming · 7 years ago

Is there enough CO2 on Earth to make the atmosphere 1% CO2?

A climate skeptic recently opined that there wasn't enough CO2 on Earth to make the atmospheric CO2 concentration 1% by volume. However, there is an estimated 3.5 x 10^23 grams of carbonate rock on the planet. The mass of the atmosphere is 5 x 10^21 grams. So there is about 100 times more carbonate rock than there is gas in the atmosphere. Normalizing for the number of moles of each and assuming all the carbonate is present as CaCO3, factoring in the difference in molecular weights, this works out to about 10 times as many moles of CO2 available as there are moles of atmosphere, meaning it would take 1/1000 of the total CO2 available as carbonate to make the atmosphere 1% CO2 (and that is neglecting the amount of CO2 available in the deep ocean).

So, the skeptic clearly didn't know what he was talking about. Given this lack of understanding of some very basic geology and ability to do simple arithmetic, how can we trust the ability of climate skeptics to evaluate anything about the science related to climate?




XG: When you're in a hole, stop digging. I would stick to responding to questions that don't require having taken chemistry in high school to understand.

Update 2:

XG: When you're in a hole, stop digging. I would stick to responding to questions that don't require having taken chemistry in high school to understand.

Update 3:

JFC Jim, are you insane? Are you really a geologist? WTF? You *really* want to claim that carbonate rocks don't have recoverable CO2 in them? Really? I mean, before this I was willing to believe you knew maybe a little about rocks (although my hunch is you mostly know about things like soil compaction and placement of drainage fields for septic systems), but that answer is baffling to me. Crack open one of your elementary geology texts and find out how the White Cliffs of Dover formed. Now, I'm going to snicker even harder when you claim you are a scientist.

CR: What the hell are you talking about? Mole fraction in the gas phase at these temperatures and pressures is a very good approximation for volume fraction. PV=nRT and all that.

And Dave, read for comprehension. The statement was whether there was enough available CO2 in total, not whether existing hydrocarbon sources, when combusted, would produce enough CO2.

Anyone who thinks 1% total CO2 is not possi

9 Answers

  • Trevor
    Lv 7
    7 years ago
    Favorite Answer

    Currently the atmospheric concentration of CO2 is 396 parts per million by volume (ppmv) and 600 parts per million by mass (ppmm). The total mass of CO2 is 3.06 x 10^18 grammes.

    As you say, if we normalise for the number of moles and assume the C is present in calcium carbonate then the chemical reaction can strip out the Ca to leave the C and O with the C oxidising to CO2. So in much the same way as burning 1kg of fuel produces ≈ 3kg of CO2, you’re going to get the same outcome from the CaCO3 and therefore the potential atmospheric mass of CO2 will be significantly more than the mass of C.

    The molar mass of CaCO3 is 100 ((1 x 40) + (1 x 12) + (3 x 16)) with the C mass being 12.000%. If your figure of 3.5 x 10^23 grams of carbonate rock on the planet is correct (no reason to suspect it’s not) then C = 4.2 x 10^22g, reacted with O to produce CO2 gives a mass of 1.54 x 10^23g of CO2 (C = 12, CO2 = 44).

    1.54 x 10^23 ÷ 3.06 x 10^18 = 5,032.

    • 396ppmv x 5.032 = 1,992,941ppmv (of the current atmospheric composition). Or… if all the carbon as CaCO3 were converted to CO2 then the atmosphere would be approx 67% CO2, 26% N, 7% O and 0.3% Ar.

    • 600ppmm x 5.032 = 3.019,608ppmm (of the current atmospheric composition). Or… if all the carbon as CaCO3 were converted to CO2 then mass of the atmosphere would quadruple.

    Of course, all of this is hypothetical as it isn’t going to happen, and couldn’t realistically happen without some powerful external interstellar or intergalactic influence.

    But the point of your question was to establish if the “skeptics” have the ability to evaluate anything about the science related to climate, and clearly some of them don’t. In fact, you only have to look at their past record to see just how little scientific or mathematical evaluation is applied to their statements.

    It often seems to be a case of the skeptics saying something because it sounds as if it might oppose the theory of global warming, the fact that in the many cases it’s complete nonsense appears inconsequential. Often the problem is that the skeptics lack the requisite knowledge to realise their own errors. If they had a greater scientific intellect they wouldn’t make so many basic errors. The same applies to the advocates of global warming too, but even a cursory examination of the evidence reveals that this characteristic is predominantly the preserve of the skeptic.

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  • Kano
    Lv 7
    7 years ago

    That was a reasonable statement to make.

    Of course there are many more times carbon in the earth to make more than 1% CO2 but not by any reasonable means or by any way liable to happen.

    You though are being unreasonable quoting facts and figures, that are possibly true, but have nothing to do with the question of climate change.

    The truth is 1% CO2 is very unlikely to ever happen, which was what the man was trying to say.

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  • JimZ
    Lv 7
    7 years ago

    Carbonate rocks may have carbon and oxygen and they may have mostly formed from earlier CO2 but that doesn't mean they are composed of CO2. It would take a pretty good sized and long lasting fire ball to warm that carbonate enough to release CO2 from carbonate rock buried kilometers deep. I don't think I would be worried about the CO2 in that case.


    According to this chart, carbon is approximately 1800 ppm of the Earth's crust. We could combust all the carbon in the crust as well.

    Why do you stop at carbonate rocks?

    If you go into the mantle, carbon is present there as well. We could cook the diamonds into CO2.

    Besides hydrogen, helium, and oxygen, carbon is the most abundant element in the universe.

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  • DaveH
    Lv 5
    7 years ago

    The atmosphere was over 20% co2 for most of the Archean eon, and that carbon hasn't magically reached escape velocity, however i don't think 1% (10,000 ppm) is achievable from fossil fuel reserves.

    There's approximately one trillion tonnes of known coal reserves. If i assume this is all carbon, then triple it (back of an envelope stuff here) to allow for the mass of oxygen, then double it, to account for undiscovered reserves, then double again to allow a similar amount for oil...

    ... I'm still 5 zero's short of getting to the 1% going by your figures for the mass of the atmosphere.

    Edit. I suddenly realised there's a lot in the oceans and biosphere.

    1% atmosphere is CO2 = 5,000,000 gt CO2

    The total amount of carbon in the oceans, atmosphere and biomass... that's about 45,000 gt.


    If all this were re-emitted to the atmosphere, we're still the 5 zero's short of 1%.

    Edit GCNP. I read your note. Re is there enough carbon, in total, available to make the atmosphere 1% CO2?... yes, easily, as I said in my first sentence.

    Edit. Here.


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  • 7 years ago

    First of all, rather than demean XG, why don't you explain why XG is digging a hole.

    Burt Rutan extensively covers that subject in the following document.


    He comes up with the conclusion, "We do not have enough fossil fuels to drive the atmospheric level of CO2 to anywhere close to a dangerous level." Page 32.

    Other scientists have expounded on this with the same conclusions.

    < So there is about 100 times more carbonate rock than there is gas in the atmosphere> Are you referring to limestone? Just how is man going to convert limestone into CO2? Limestone is CaCO3. Now how do you get CO2 out of that? Do we burn it? Have you ever tried to burn limestone? What do you suggest that man does which converts limestone into CO2?

    Or maybe you are referring to dolomite (CaMg(CO3)2), the other major carbonate rock. Again you see CO3 not CO2. Well, you might say, the potential is there. All we have to do is get rid of the magnesium and the calcium and rip away an oxygen atom and we have CO2. Ha! Ha! What process is that? And who would want to go to the expense of doing it just to foul up the earth's atmosphere?

    You are good at putting people down but short on logic. Ha! Ha! But thanks for the laugh.

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  • Anonymous
    7 years ago

    For a gaseous mixture, percent by volume is meaningless. You add a gas to a mixture, you would be more likely to increase the pressure. A gas in air has a mole percent or a percent partial pressure. For in ideal gas, the numbers are the same.

    But, is there enough carbon to give Earth's atmosphere 1 mole % carbon dioxide? I suspect that there is enough in limestone and dolomite for much more than that. I certainly hope that we run out of fossil fuels before then and switch to clean energy.

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  • 7 years ago

    There is enough co2, oxygen, methane and nitrogen stored in rocks to make the atmosphere at least 10 bar/10x thicker than it currently is.

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  • 7 years ago

    I suppose technically it's possible. For example if you removed all the oxygen and nitrogen from the atmosphere, it would be 93% argon and 4% CO2.

    Or if all CO2 in the oceans outgassed and all plant life died you might get 1% CO2.

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  • 7 years ago

    Not for a long time the CO2 level is only 0.035% Hope this helps

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