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  • convert GtCO2 to ppm rise in atmosphere

    Hi

    How do you convert, rather calculate the rise in atmospheric concentration of CO2 by emission of 1GtCO2 (=gigatonne). Is the below approach correct, I am not sure. Could anybody advise, please. I think what I have done below is wrong.

    1PPM CO2= 2.12 GtCarbon ( IPCC and Gilbert Masters)

    Therefore IGt Carbon= 1/2.12= 0.47ppm CO2

    1 tonne Carbon=3.66 tonne CO2

    therefore 1tCO2=1/3.66=0.27 tonnes carbon ( conversion factor)

    so 1Gt CO2=0.27 GtCarbon

    1 GtCO2 emission =0.27/2.12=0.127 PPM of CO2 rise in atmosphere

  • #2
    Re: convert GtCO2 to ppm rise in atmosphere

    Originally posted by unreg View Post
    Hi

    How do you convert, rather calculate the rise in atmospheric concentration of CO2 by emission of 1GtCO2 (=gigatonne). Is the below approach correct, I am not sure. Could anybody advise, please. I think what I have done below is wrong.

    1PPM CO2= 2.12 GtCarbon ( IPCC and Gilbert Masters)

    Therefore IGt Carbon= 1/2.12= 0.47ppm CO2

    1 tonne Carbon=3.66 tonne CO2

    therefore 1tCO2=1/3.66=0.27 tonnes carbon ( conversion factor)

    so 1Gt CO2=0.27 GtCarbon

    1 GtCO2 emission =0.27/2.12=0.127 PPM of CO2 rise in atmosphere
    I think your result is correct, but perhaps a little roundabout. Using 1 tonne Carbon=3.66 tonne CO2, I would simply observe 1 ppm CO2 = 2.12 Gt carbon or 7.76 Gt CO2. Taking the reciprocal, I get 0.129 ppm/Gt CO2. The difference is probably due to rounding differences in the two ways of proceeding. (I would suggest 1/3.66 should be carried to a 3rd place, 0.273, but that is splitting hairs)

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    • #3
      Re: convert GtCO2 to ppm rise in atmosphere

      Thank you John

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      • #4
        Re: convert GtCO2 to ppm rise in atmosphere

        Originally posted by JohnS View Post
        I think your result is correct, but perhaps a little roundabout. Using 1 tonne Carbon=3.66 tonne CO2, I would simply observe 1 ppm CO2 = 2.12 Gt carbon or 7.76 Gt CO2. Taking the reciprocal, I get 0.129 ppm/Gt CO2. The difference is probably due to rounding differences in the two ways of proceeding. (I would suggest 1/3.66 should be carried to a 3rd place, 0.273, but that is splitting hairs)
        Does this take account of the observation that only ~46% of emitted CO2 goes into the atmosphere, and the rest into ocean and other sinks?
        Mond from Oz

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        • #5
          Re: convert GtCO2 to ppm rise in atmosphere

          Originally posted by Unregistered View Post
          Does this take account of the observation that only ~46% of emitted CO2 goes into the atmosphere, and the rest into ocean and other sinks?
          Mond from Oz
          No, it considers no equilibriums with oceans, biomass, etc. It is the total weight of an incremental ppm in the atmosphere.

          If you had all these equilibriums, and the atmosphere still increased one ppm, there would be additional carbon elsewhere to be accounted for. No one can really account for all the emitted carbon, so they look at atmospheric concentrations away from local concentrated sources (don't measure next to a smokestack).

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          • #6
            Re: convert GtCO2 to ppm rise in atmosphere

            hi... this conversion is quite very helpful. can anyone guide me that how many tons of CO2 or ppm of CO2 can raise atmospheric temperature by 1 degree celsius?

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            • #7
              Re: convert GtCO2 to ppm rise in atmosphere

              A doubling of CO2 will raise temperatures by 2-4.5 degrees celcius, with 3 degrees as best estimate. Using that number, we need 1/3 of a doubling to get to 1 degree. 1/3 of a doubling is (2^(1/3)), or about 1.26. So we need to increase the CO2 by that factor to get a 1 degree warming. Currently the CO2 is at 400 ppm, so to get an additional 1 degree warming the CO2 -level needs to increase to 400*1.26=504ppm. So the answer is an increase of 504-400=104 ppm CO2 is needed to increase the temperature by 1 degree.

              A few caveats:
              1) More CO2 would be needed to get to the next degree of warming, because additional CO2 has a reduced effect. E.g. the next degree would need an increase of (504x1.26-504) 131 ppm.
              2) It will take a long while before this temperature will be felt in the actual world, because the oceans take a long while to warm up.

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              • #8
                Re: convert GtCO2 to ppm rise in atmosphere

                Originally posted by Unregistered View Post
                hi... this conversion is quite very helpful. can anyone guide me that how many tons of CO2 or ppm of CO2 can raise atmospheric temperature by 1 degree celsius?
                You are asking what the climate sensitivity is to CO2; no-one knows this due to the uncertainty in feedbacks, primarily clouds and water vapor.
                All we do know for sure, is the rise without feedbacks; i.e. a Forcing of 3.8W/m2 is caused by a doubling of CO2 in the atmosphere)


                Temp change = Forcing x Landa

                1.14c = 3.8W/m2 x 0.3

                Therefore to get a 1c rise at equilibrium from now, we would need to almost double present CO2 concentrations to 780ppm.

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