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If we burn all carbon in the Earth's crust, by how much would the atmospheric concentration of CO2 increase?

Gimelist
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user3368561
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    There are things you can look up. The first hit on the Google search for "carbon content earth crust" brings you to the Wikipedia article Abundance of elements in Earth's crust. Then you search for the thickness of the crust, the size of the earth, and calculate the crust volume. If somewhere along the way your are stuck or doubt your calculations, then is the time to ask. This is not a can you do my work for me site. – Jan Doggen Jun 08 '15 at 13:18
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    @JanDoggen It is a place were you can find answers to frequently asked questions. If no one ask the question first, no one with the same doubt will find it. Nobody forces you to answer the question. – user3368561 Jun 08 '15 at 13:23
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    I don't think you could burn all the carbon, just that fraction that is stored in fossil fuels. Carbon-containing minerals like limestone would need energy inputs applied to free the carbon/CO2. – jamesqf Jun 08 '15 at 17:47
  • Using conservative estimates, the total mass of carbon in the crust, when burned into CO2, would be around 5 times the current mass of the atmosphere. – 2012rcampion Jun 09 '15 at 02:35
  • @jamesqf What is the mass of carbon that is stored in remaining fossil fuels? Don't forget that current biomass can also be burned. – user3368561 Jun 09 '15 at 06:58
  • @2012rcampion This is an answer. Why you put it as a comment? – user3368561 Jun 09 '15 at 06:58
  • @user3368561: I don't believe anybody really knows for sure, as new discoveries are made from time to time. Estimates of existing reserves can likely be found using Google. – jamesqf Jun 10 '15 at 18:13
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    Do you mean the bulk of the extractable carbon fuel (coal, tar, oil, natural gas that can be removed). Or the total burnable carbon fuel, most of which cannot be extracted. Or the total reduced (not oxidized) carbon. Or the total carbon without regard to chemical state (mostly unburnable minerals). Those are 4 different Q's with 4 different answers. – Eubie Drew Oct 22 '15 at 17:42
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    @Aabaakawad All carbon, as chemical element. This question is answered. Because there are more carbon than oxygen, we can only burn until oxygen runs out, so the answer is 21%. – user3368561 Oct 22 '15 at 19:53
  • Surprisingly, it was forbidden to ask a similar question on the oxygen. – Little Alien Sep 14 '16 at 15:17
  • @LittleAlien: I suspect that that is more a problem of that question being poorly phrased and hard to understand, as well as you insulting people who were trying to help. Despite that, your question got answered twice anyway. – naught101 Sep 19 '16 at 03:26

2 Answers2

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Short answer: $\rm CO_2$ levels would increase by $209,460$ $\rm ppm$ by using all the available oxygen.

Long answer: The mass of carbon in Earth's crust is $9(10)^{22}$ $\rm gC$ (grams of Carbon). The mass of the atmosphere is $5.15(10)^{21}$ $\rm g$. If all the carbon was burned, or otherwise moved to the atmosphere, then the limiting factor would be the $\rm O_2$ (molecular oxygen) available for carbon to bond with to make $\rm CO_2$. Oxygen makes up $209,460$ $\rm ppm$ of the atmosphere. So, assuming the carbon bonded with all available $\rm O_2$ and the remaining carbon did not enter the atmosphere, then there would be an additional $209,460$ $\rm ppm$ of carbon dioxide in the atmosphere.

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Matthew
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Biological answer: The amount of $CO_2$ would be in the range $100-600$ $ppm$, like it is today. The carbon from the crust would be completely used to produce biomass; there will be more living creatures on Earth.

The lower range of $100$ $ppm$ is defined by C4-plants; their ability to use $CO_2$ collapses at these levels. The upper range is practically only $400$ $ppm$, and it's defined by C3-plants: their ability to use $CO_2$ doubles if the amount rises from $300$ $ppm$ to $600$ $ppm$. As humans produce less than $10\%$ of the world's $CO_2$ it means that even with 5 times the growth, the total $CO_2$ production in the world would only be $150\%$, which the existing plants can absorb at approx $400$ $ppm$ $CO_2$ levels. It's more probable though, that the $CO_2$ level wouldn't arise at all, the existing plants just grows a bit quicker and vegetation would spread to deserts and plankton in the sea would grow more. These phenomena are already observed.

I can only provide a Wiki link on German language. Look the picture Co2-absorbtion by plants

"CO2-Aufnahme" Pls note that 0.02% = 200 ppm etc

The comment of Gordon Stanger forces me to improve this answer.

The evolution of the plants was totally different 60 Million years ago. The plants have of course now built their systems to current levels. If you study Bryophyte, you will find that even $2000$ $ppm$ is not a problem for them; they will just grow like crazy. I've tested that personally, with pure $CO_2$. Unluckily most of the good material I know, is in Finnish language; Mire cover 5% of earth. 80% untouched Mainly Canada and Siberia. They can easily absorb any amount of $CO_2$ you desire to feed in atmosphere. Nowadays the rate might average $4.8$ $t/ha/a$, with $400$ $million$ $ha$ total amount, this alone makes almost $20$ $000$ $Mt/year$. This is comparable for the World fossil energy consumption, which is $13$ $000$ million tonne of Oil Equivalent in year. To point the scales out, approx $60\%$ of fossil fuels are coal, and the rest is hydrogen, which result is water. So these mires can alone absorb the whole $CO_2$ production of mankind. Even if they would feedback as much by themselves.

This absorption rate varies already from $1$ $to$ $10$ $t/ha$, even though we have not even seen $400$ $ppm$ $CO_2$ values. Well, for a short period during spring such a levels occur. Pls go to Lappland, at that time an experience the crazy growth of nature. They even change their color, to use wider spectrum of sunlight to their usage.

Maybe 60 million years ago all the plants were yellow.

The Comments of Dikran Marsupial answered here:

Tell me, how long did it take those peat bogs to form? Here is told how in 1957 a peat bog was dug clean; in 2010 they measured over 0.5 m thickness; Approx 1 cm/ year. This means that a average thick Finnish peat bog, 1.41 m, could crow in 141 Years.

Next calculate the rate of deposition required to soak up anthropogenic fossil fuel emissions at their current rate. (source, your answer) Current rate is $9200$ $Mt$, i.e. with just $1$ $t/ha$, The worlds mire's 400 Million ha; Absorb $400$ $Mt$, at $5$ $t/ha$, $2000$ $Mt$, and at $10$ $t/ha$ $4000$ $Mt$, i.e. 40%. This is from $3\%-5\%$ of the Earth's land surface.

I think your answer has some mistake on you calculations. Your forest grows only $1.5$ $t/ha$. The average forest growth in Finland is $8m^3$/ha /year. This is -again- approx $4.8$ $t/ha/year$.

Claim: We would need to turn 42% of the Earths land surface into peat bogs (or forests?) I make this simple; according to this link; Peat lands are storing on average 10 times more carbon per hectare than other ecosystems. Peat lands occur in 180 countries and cover 400 million hectares or 3% of the world's surface. So if we have 3%, which counts for 30% of average forest, we only need 3% peat lands and 12% forest. But we have 30% forest!.

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Jokela
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  • This is the realistic answer (thanks for it). However I have assumed the worst-case scenario, though it never will happen. – user3368561 Nov 06 '15 at 13:27
  • So can we estimate by how much the biomass would increase? Surely its not the case that it would spread a bit, but cause large-scale eruptions of plant growth? – AtmosphericPrisonEscape Nov 06 '15 at 17:47
  • @AtmosphericPrisonEscape The estimations are actually quite easy to make; you look the world population. At 1700 no fossiles were used, world population was 700 Mio, now it's 7 000 Mio. So only for the population growth; 70 kg x 18.5% x6200 000 000 = 80 mio tons of coal is needed to make it possible. Not much, you might think, but please spread this math to the food production, American's eat a ton/year, If we calculate that 400 kg's is coal, and scale it to the world; you need 2 480 mio Tons. I hope you can see the scale by these examples. All the production animals also need their part. – Jokela Nov 07 '15 at 08:34
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    Jokela Turbine's answer is totally wrong, and reminiscent of climate-science skepticism's spurious arguments. A ceiling of only 600 ppm CO2 is demonstrably preposterous, given that the known Palaeogene CO2 averaged about 2000ppm and peaked at well in excess of 3000 ppm. A global transition to C3 photosynthesis is also preposterous, not to mention the resulting global famine (most of our crops are C4). The '600 ppm CO2 ceiling' fails to take into account about 20 feedback mechanisms, the oceanic chemistry effects, and is massively unrealistic about humanity's addiction to fossil fuels. – Gordon Stanger Nov 07 '15 at 09:18
  • @GordonStanger I updated my answer according to your comment. – Jokela Nov 07 '15 at 10:26
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    A "back of the envelope" calculation shows that biological growth is not able to prevent CO2 levels from rising, even from current levels of fossil fuel use it would require reforesting 42% of the Earths land surface, which is clearly impossible http://earthscience.stackexchange.com/questions/2639/how-many-trees-would-i-have-to-plant-to-solve-global-warming/2642#2642 . Note also that forests are only carbon sinks while they are actively growing, once they mature, they are not going to substantially hold back atmospheric increase any longer. – Dikran Marsupial Nov 17 '15 at 10:47
  • @DikranMarsupial Only in Finnland there is 30 mrd m3 biomass stored in the technically usable mire's. This equals 2x time the known oli reserves of north sea. It's 35 times the amount compared to Finnish the forests. And the mires less than 0.3 m thick wasn't even calculated here. http://www.gtk.fi/_system/print.html?from=/_system/PressReleases/news_0206.html – Jokela Nov 17 '15 at 11:12
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    I take it you mean peat bogs? Tell me, how long did it take those peat bogs to form? Next calculate the rate of deposition required to soak up anthropogenic fossil fuel emissions at their current rate. I suspect you will find that it is not nearly fast enough. – Dikran Marsupial Nov 17 '15 at 14:59
  • @DikranMarsupial Mire's grow with the very same rate's as the forests if in same location. And they follow the stuff presented in my answer. Bryophyte is a C3-plant. The fossil fuel emissions are about 7% of the whole coal-cycle. You'll find out that they barely make a measurable diffence. I think I sort of calculated this already in my answer. Please note that if that "H" burns to water. I wrote "hydrocarbon", but meant "Hydrogen", I'll correct that if some other stuff adds in. -And Peat bogs is only an special case of a Mire. + I have no need to argue about these issues. – Jokela Nov 17 '15 at 16:31
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    In that case, if the rate is the same as forests, we would need to turn 42% of the Earths land surface into peat bogs, which is impossible. Note the volume of the reservoirs is irrelevant, it is the rate at which the can sequester CO2. You do need to argue about these issues for your answer to be convincing. – Dikran Marsupial Nov 17 '15 at 17:12
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    Incidentally, this paper (http://onlinelibrary.wiley.com/doi/10.1111/j.1529-8817.2003.00783.x/pdf) suggests 72gm^-2 as a maximum sequestration rate, which is 0.72 tons per hectare per annum, which is rather less than your figure, and it is rather doubtful that the whole of the earth wetlands are operating at that sort of rate all the time. – Dikran Marsupial Nov 17 '15 at 17:22
  • @DikranMarsupial I agree with your paper. I did wrote my self; "This absorbtion rate varies allready from 1 to 10 tn/ha." And if you have some small peat bog surrounded by Forrest the value can be less. Here; http://www.tiede.fi/artikkeli/jutut/artikkelit/suo_syntyy_uudestaan is said "5 000 kiloa hehtaarilla" means 5 tn/ha. -rate varies according to CO2-amount. You need place like this; http://www.sirkkaimage.com/-/archive/other-protected-areas/rokua-geopark/oulujarvi-area/kuvajan-aapasuo/-/medias/e55aa2cc-fc1f-11e2-9ccd-3742671e453b-kuvajan-aapasuota-rumala-kuvajan-soidensuojelualueella – Jokela Nov 17 '15 at 17:42
  • @JokelaTurbine, as far as I can see, the paper I mentioned rules out rates even as high as your minimum of 1 ton per hectare per year, the maximum rate they give is 0.72 and the minimum is 0.14, which is approximately an order of magnitude less. – Dikran Marsupial Nov 17 '15 at 18:50
  • @DikranMarsupial Sorry, but so low rates are not even counted as Forrests in Finnland. Typical peak growth is 12 m3/ha/a; 7.2 tn biomass. maybe 5 tn coal. I've own forest. And I hope you don't mix acre and ha. – Jokela Nov 17 '15 at 19:15