• This is a political forum that is non-biased/non-partisan and treats every person's position on topics equally. This debate forum is not aligned to any political party. In today's politics, many ideas are split between and even within all the political parties. Often we find ourselves agreeing on one platform but some topics break our mold. We are here to discuss them in a civil political debate. If this is your first visit to our political forums, be sure to check out the RULES. Registering for debate politics is necessary before posting. Register today to participate - it's free!

Carbon 13 Ratios and Radiative Forcing

Lord of Planar

Supporting Member
DP Veteran
Monthly Donator
Joined
Dec 22, 2012
Messages
65,940
Reaction score
21,952
Location
Portlandia
Gender
Male
Political Leaning
Libertarian - Right
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?
 
Last edited:
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?
Their is no way raising co2 levels would lower temp. I would be very skeptical of any data set that claims they do.

Furthermore adding co2 to the atmosphere is ill-advised not only because of heating, but also because of ocean acidification.
 
Their is no way raising co2 levels would lower temp. I would be very skeptical of any data set that claims they do.

Furthermore adding co2 to the atmosphere is ill-advised not only because of heating, but also because of ocean acidification.
Look into what radiative efficiency is first. It's not the 12C increasing that causes a possible cooling if the change in isotopic ratios are enough, but the lowering of the 13C in the atmosphere. Each isotopic molecular mix has its own forcing value. They should be individually plotted on a log curve. An equal change in CO2 molecules with 13C has 200 times the forcing change as CO2 with 12C. Therefore, if we were to increase CO2 by 1 ppb, and at the same time, decrease CO2 with 13C by 1 ppb, the net effect is cooling. The drop in 13C would have to be maintained as CO2 levels increase for this to be a net cooling by CO2. My point is, this is possible if 13C levels are dropped by enough.
 
Look into what radiative efficiency is first. It's not the 12C increasing that causes a possible cooling if the change in isotopic ratios are enough, but the lowering of the 13C in the atmosphere. Each isotopic molecular mix has its own forcing value. They should be individually plotted on a log curve. An equal change in CO2 molecules with 13C has 200 times the forcing change as CO2 with 12C. Therefore, if we were to increase CO2 by 1 ppb, and at the same time, decrease CO2 with 13C by 1 ppb, the net effect is cooling. The drop in 13C would have to be maintained as CO2 levels increase for this to be a net cooling by CO2. My point is, this is possible if 13C levels are dropped by enough.
I know what radiative efficiency is. I'm just bad at math lol (not that bad tho...)

Oh I see. But you would still have to do something with all that co2, and to have any real effect worldwide it would be ALLOT of co2.

It is a interesting idea. You wouldn't need to be adding any co2 to the atmosphere though, because plenty is already being added, and its cool that their would be a net gain in cooling for every ppb added vs every ppb taken, but you would also need to factor for the amount of energy it would take to remove the co2

The only way I know of to get co2 out of the atmosphere without using electricity/fuel is to sequester it in dirt/plants. And thats only if you dont use equipment like tractors and roto tillersThis would be all the more reason to convert the world to a no till organic system in order to preserve the micro flora and fauna that are so good at doing this. Pesticides and over tilling kill them and make it so the dirt can sequester allot less.

Also I believe the main concern with co2 is actually ocean acidification. Methane is the biggest culprit for warming... That's why agriculture is the biggest polluter, all the methane...
 
Last edited:
Look into what radiative efficiency is first. It's not the 12C increasing that causes a possible cooling if the change in isotopic ratios are enough, but the lowering of the 13C in the atmosphere. Each isotopic molecular mix has its own forcing value. They should be individually plotted on a log curve. An equal change in CO2 molecules with 13C has 200 times the forcing change as CO2 with 12C. Therefore, if we were to increase CO2 by 1 ppb, and at the same time, decrease CO2 with 13C by 1 ppb, the net effect is cooling. The drop in 13C would have to be maintained as CO2 levels increase for this to be a net cooling by CO2. My point is, this is possible if 13C levels are dropped by enough.

How exactly would we be able to change the naturally occurring ratio of isotopic carbons?
 
How exactly would we be able to change the naturally occurring ratio of isotopic carbons?
Fossil fuels have far lower 13C than what is already in the atmosphere. Therefore, as we burn oil, the ratios of the atmosphere change.
 
Fossil fuels have far lower 13C than what is already in the atmosphere. Therefore, as we burn oil, the ratios of the atmosphere change.

Ok but you just posted that the C13 molecules have a 200X effect over the C12 molecules so if the 12 has less than the 13 I'm not following your argument unless you are proposing that there will be a lowering of the overall climate. If this is the case your argument is contrary to the empirical evidence,
 
Ok but you just posted that the C13 molecules have a 200X effect over the C12 molecules so if the 12 has less than the 13 I'm not following your argument unless you are proposing that there will be a lowering of the overall climate. If this is the case your argument is contrary to the empirical evidence,
OK, consider this.

If I decrease CO2 with C13 by 1 ppb, and increase CO2 with C12 by 100 ppb, then my (200 RE x 1 ppb) > (1 RE x 100 ppb ). The effect would be similar as if I decreased CO2 by the 100 ppb.
 
OK, consider this.

If I decrease CO2 with C13 by 1 ppb, and increase CO2 with C12 by 100 ppb, then my (200 RE x 1 ppb) > (1 RE x 100 ppb ). The effect would be similar as if I decreased CO2 by the 100 ppb.

How does the chemical reaction of burning CO2 relate to the nuclear decomposition of carbon 13 to carbon 12?
 
How does the chemical reaction of burning CO2 relate to the nuclear decomposition of carbon 13 to carbon 12?

I think the carbon in fossil fuel has less C13 in it because it was last exposed to the Sun a long time ago.

I don't understand why C12 and C13 have different radiative characteristics though. My limited science.
 
I think the carbon in fossil fuel has less C13 in it because it was last exposed to the Sun a long time ago.

I don't understand why C12 and C13 have different radiative characteristics though. My limited science.

He was asking why the half-life would be different in the atmosphere I believe...
 
Ok, almost finished my first cup of tea, I see what you are driving at.
fossil fuel emissions produce CO2 with a much higher concentration of carbon-12
than the existing CO2 from the normal cycle.
on our path to doubling CO2, the ratio of C-13 to C-12 will change.
I am still trying to wrap my head around why the difference in ratio would cause
some cooling.
 
I think the carbon in fossil fuel has less C13 in it because it was last exposed to the Sun a long time ago.

I don't understand why C12 and C13 have different radiative characteristics though. My limited science.

Oh ok I get it thanks. Not sure why C12 and C13 have different radiative characteristics either.
 
I think the carbon in fossil fuel has less C13 in it because it was last exposed to the Sun a long time ago.

I don't understand why C12 and C13 have different radiative characteristics though. My limited science.
Give me a little time, and I will plot it in excel for everyone.
 
He was asking why the half-life would be different in the atmosphere I believe...

It wouldn't be that since they are both stable.

The theory is since fossil fuels are made from long decayed life, and vegetation prefers 12C over 13C in the photosynthesis process, that the oil in the earth has almost no 13C. There may be other reasons, but the fact remains that fossil fuels have almost no 13C in their composition. Maybe at one time there was no 13C in the earth, and something triggered the making of 13C.

I don't really know, other than the fact that crude oil has almost no 13C.
 
Give me a little time, and I will plot it in excel for everyone.

You might have to explain how carbon emits IR differently due to it's mass..... although does a chromatic spectrometer use that....???

Good luck explaining it to us all.
 
It wouldn't be that since they are both stable.

The theory is since fossil fuels are made from long decayed life, and vegetation prefers 12C over 13C in the photosynthesis process, that the oil in the earth has almost no 13C. There may be other reasons, but the fact remains that fossil fuels have almost no 13C in their composition. Maybe at one time there was no 13C in the earth, and something triggered the making of 13C.

I don't really know, other than the fact that crude oil has almost no 13C.

I have read some stuff arguing that oil is nothing to do with fossil fuel. That it is in fact just carbon oozing out of the Earth's depths. That it collects in pockets when it is stopped from getting to the surface and that If we drill deep enough there is lots more of it down there... The C13/12 thing would fit with that if it is that they are both stable.
 
If you look at this graph:

CO2forcing_zps17b60101.png


Notice the slopes of each. For 13C it is 3.23 (y = 3.2311x) and for 12C it is 0.0123. Because forcing is on a log curve, the slope is constantly reducing as the value increases. For small changes, the slope can be used for estimated changes. CO2 with 12C has a slope of 0.0123, it takes a change of 81 ppm to change the the forcing by 1. However, it only takes a change 0f 0.3 ppm to make the same forcing change of 1 for CO2 with C13.

Isotopic values of relative spectral line values in the atmosphere for all forms of CO2 are illustrated here:

spectralcalcCO2isotopes.jpg


Does this explain well enough why small changes in CO2 with 13C are more dramatic than CO2 with 12C?
 
You might have to explain how carbon emits IR differently due to it's mass..... although does a chromatic spectrometer use that....???

Good luck explaining it to us all.
The mass might make a minor change in forcing of equal quantities, but I don't expect it to be significant. I would expect CO2 with 12C and CO2 with 13C to fall close enough on the same log curve.
 
The mass might make a minor change in forcing of equal quantities, but I don't expect it to be significant. I would expect CO2 with 12C and CO2 with 13C to fall close enough on the same log curve.

If there is no difference between the 2 why all the fuss?
 
Oh ok I get it thanks. Not sure why C12 and C13 have different radiative characteristics either.
Probably different masses or molecular makeups due to lack of sun exposure...

Keep in mind all radiative characteristics are is what happens when a projectile electron displaces the inner shell of a atom...

So a different mass atom or a different makeup of atoms would produce a different result...

If you already know this then sorry that's where my understanding craps out... I'm much better with botany than physics...
 
There is a difference. They respond to different spectral lines, hence they deserve individual calculations.

If I understand it at all; your graph is of the different sorts of CO2 (different isotopes) and the way they absorb IR.

OK, as I understand it (which is not a lot) you then need to multiply that by the amount of IR coming in, the degree to which they absorb it, the degree and way they re-emit it, the various fractions of the air/CO2 they make up, and probably some other stuff. Once you have done all this you are on rung one of a long ladder of modeling the greenhouse effect.

All the various terms will be as complex or worse than the graph you posted.

Good luck on that. I think it sounds like a PhD thesis at least.
 
There is a difference. They respond to different spectral lines, hence they deserve individual calculations.
I think I get it, the carbon in the middle of the CO2 has a higher atomic weight
for C-13 than for C-12.
This changes the vibrational energy states, which change both the absorption and emission spectra.
Carbon%20Isotope.jpg

I was thinking of the vibrations on a guitar string with different weights on the string,
they would produce different sounds/wavelengths.
 
Back
Top Bottom