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I never really thought much about the debate of how much man made CO2 remains in the atmosphere, but I just had an epiphany... Something I never heard mentioned before.
I don't think anyone disagree that carbon 13 level percentages have decreased in atmospheric CO2 If we use Böhm et. al 2002, the levels have changed from about 0.495% to 0.38% (extrapolated) during the assessment timeframe of the AR4. However, 278 ppm in 1750 means 1,376 ppb was CO2 with 13C and it rose to 1,440 in 2005. Since we have a net increase in CO2, we do with 13C as well. Since forcing is on a log curve, and if we assess the RE (radiative efficiency) separately, we get 0.00303 for CO2 with 13C and 0.0000151 for CO2 with 12C for the 1750 levels and 0.0029 for CO2 with 13C and 0.0000111 for CO2 with 12C for the 2005 levels. What this amounts to, if we take the stated 1.66 W/m^2 warming is that 0.21 W/m^2 of it was from CO2 with 13C and 1.45 W/m^2 from CO2 with 12C, or if the 1.66 W/m^2 is calculated for just the CO2 with 12C, then we can add another 0.24 W/m^2 for 13C increases.
Now what this means, can be important. I haven't looked at other studies, only this one for the values. However, if the values are wrong, and 13C is diminishing less than previously thought, and if the 1.66 W/m^2 is based only on CO2 with 12C, the individual forcing of CO2 made with 13C could possible cool the atmosphere more than the increasing 12C warms it. For example, since the RE of 13C is 200 times greater than the RE of 12C, if the atmospherics percentages of 13C actually dropped from about 0.5%, in half, to about 0.25%, then all the increased CO2 would provide a net cooling of about 0.2 W/m^2. This is because 13C would actually drop to 948 ppb, and it's radiative efficiency is so much higher.
Don't get me wrong, I don't think the 13C percentages have halved, or close, but this is food for thought.
What do you guys think, or do you have different 13C values in mind?
I don't think anyone disagree that carbon 13 level percentages have decreased in atmospheric CO2 If we use Böhm et. al 2002, the levels have changed from about 0.495% to 0.38% (extrapolated) during the assessment timeframe of the AR4. However, 278 ppm in 1750 means 1,376 ppb was CO2 with 13C and it rose to 1,440 in 2005. Since we have a net increase in CO2, we do with 13C as well. Since forcing is on a log curve, and if we assess the RE (radiative efficiency) separately, we get 0.00303 for CO2 with 13C and 0.0000151 for CO2 with 12C for the 1750 levels and 0.0029 for CO2 with 13C and 0.0000111 for CO2 with 12C for the 2005 levels. What this amounts to, if we take the stated 1.66 W/m^2 warming is that 0.21 W/m^2 of it was from CO2 with 13C and 1.45 W/m^2 from CO2 with 12C, or if the 1.66 W/m^2 is calculated for just the CO2 with 12C, then we can add another 0.24 W/m^2 for 13C increases.
Now what this means, can be important. I haven't looked at other studies, only this one for the values. However, if the values are wrong, and 13C is diminishing less than previously thought, and if the 1.66 W/m^2 is based only on CO2 with 12C, the individual forcing of CO2 made with 13C could possible cool the atmosphere more than the increasing 12C warms it. For example, since the RE of 13C is 200 times greater than the RE of 12C, if the atmospherics percentages of 13C actually dropped from about 0.5%, in half, to about 0.25%, then all the increased CO2 would provide a net cooling of about 0.2 W/m^2. This is because 13C would actually drop to 948 ppb, and it's radiative efficiency is so much higher.
Don't get me wrong, I don't think the 13C percentages have halved, or close, but this is food for thought.
What do you guys think, or do you have different 13C values in mind?
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