Posted by cohenite
warmair, you do not know what you are talking about. The AF case for showing that ACO2 is not the sole source of the increase in atmospheric CO2 is not contradicted by any of your 3 'proofs'.
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The two references you give in your article question whether the anthropogenic sources of CO2 from land clearing have been slightly over estimated. They do not question the proposition that humans are responsible for the increase in atmospheric CO2 levels. It is in fact you who do not understand what your references are talking about, which you then compound by your failure to understand the carbon cycle.

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Posted by cohenite
In any event your 3 'proofs' are riddled with mistakes; for instance C14 is not a product of fossil fuel; and the isotope distinction between fossil fuels and natural sources is problematic.
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I am glad you understand that Carbon 14 is not a product of burning fossil fuels that is the whole point. Carbon 14 is created in the atmosphere by cosmic rays but has a half life of about 6000 years which means it is not found in fossil fuels. Therefore a reduction in atmospheric Carbon 14 is an indication that the carbon source is due to the burning of fossil fuels. As previously noted testing nukes after 1954 stuffed that method but prior to that date the amount of carbon 14 had fallen by 2%.
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We have had good measurements of atmospheric oxygen since 1990 not only have they fallen but the rate is actually increasing.

http://scrippso2.ucsd.edu/sites/default/files/imce/cgo_o2_plot.gif
http://scrippso2.ucsd.edu/

Warmair; you are outrageous! I have seen the Scripps O2 ‘depletion’ graphs and am aware of the O2 scare-mongering.

The Scripps measurements have been for 20 years and the graphs MISREPRESENT the huge amount of O2 in the atmosphere; for a rebuttal of this aspect of the AGW scare-mongering see:

http://scienceandpublicpolicy.org/images/stories/papers/scarewatch/oxygen_scarcity_scarewatch.pdf

http://motls.blogspot.com.au/2008/08/oxygen-crisis.html

The C14 marker and spike will be dealt with in a follow-up article with more detailed analysis of the ACO2 issue so I won’t bother with it now.

In respect of the AF your comment about the uncertainty of land-clearing emissions is just nonsense; Knorr tests for this and presents a number of options to ameliorate this uncertainty.

And of course Knorr does not use his study, which was to verify the constancy of the AF, to consider the issue of whether ACO2 is causing all the increase in atmospheric CO2; that is an inference made in the article; no one has rebutted it. No one has rebutted it because it is PLAIN.

It is plain as shown in Ian Hill’s graph where the increase in ACO2, atmospheric CO2 and the AF are ALL expressed in Gts. HOW can the AF, as measured in Gts, cause all of the increase in atmospheric CO2 when the Gt increase in atmospheric CO2 is GREATER than the Gts of the AF available to cause the increase in atmospheric CO2?!

All the convoluted comments from you and Bugsy ignore that basic fact; the only way you can rebut it is to say Knorr and the AF are wrong. Are they?

The effect can be compared with the principle of a constant in an increasing total: say ACO2 is 40% of all CO2 [as per the constant ACO2 AF] which is 100, so ACO2 is 40 and natural CO2 is 60; when all CO2 is 200 ACO2's 40% will be 80 so natural CO2 will be 120, an increase of 60; at 300, ACO2 is 120, natural CO2 is 180 and so on; natural CO2 MUST be contributing to the increase in total CO2.
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This is where the article is in a serious state of confusion

The airborne fraction is not the proportion of man made CO2 in the atmosphere compared to natural CO2, It is the proportion of man made Co2 which is absorbed and removed from the the atmosphere.

First of all the amount of man made CO2 absorbed by nature is roughly 60%.
The proportion of man made Co2 which is absorbed by nature has not changed by a significant amount since 1850. This is all the we really mean when we say that the airborne fraction has remained constant.

So to state the article's proposition correctly if man made Co2 doubles from 100 to 200 then the total removed by nature is 120 and 80 parts remain in the atmosphere.

In the statement above the article is claiming that 120 parts are natural CO2 which is nonsense and makes the conclusion meaningless.

Now Knorr goes in for some complicated statistics which makes a reasonable case that the proportion of CO2 absorbed by nature has remained constant over decades, but this is not expected to continue, as the concentration of Co2 rises the capacity of the oceans and biomass to absorb it should fall. At present there are some papers which indicate a recent decreasing ability of the earth's systems to remove excess Co2 from the atmosphere. [Le Que´re´ et al., 2007; Schuster and Watson, 2007; Canadell et al., 2007]

warmair concludes:

"This is where the article is in a serious state of confusion"

And then says:

"The airborne fraction is not the proportion of man made CO2 in the atmosphere compared to natural CO2"

Noone said it was.

Then;

"It is the proportion of man made Co2 which is absorbed and removed from the the atmosphere."

No, exactly the opposite; the AF is the fraction of ACO2 which is not absorbed and stays in the atmosphere.

The AF has been calculated at about 40% of ACO2, that is human emissions.

The graph by Ian Hill shows the AF as a 40% fraction of ACO2 emissions; this is expressed in Gts; this is compared with the increase in atmospheric CO2 which is also in Gts.

The AF is LESS than the amospheric increase.

Therefore the AF, which is ALL the ACO2 available to increase atmospheric CO2 increase, is NOT ENOUGH to supply ALL the atmospheric increase.

I really don't know why that is so difficult or why warmair and others are so confused!

The one who is confused the most here cohenite, is you and you don't even know it.

All this bluff and bluster doesn’t change the fact that it is you who are wrong cohenite.

Astoundingly so, in fact.

You don’t even know exactly how the airborne fraction (AF) is calculated!

Put simply, it is the change in CO2 over the total emissions. Knorr used the total emissions, similarly to Canadell, which is (F-fossil+F-LUC), that is the emissions due to fossil fuel burning plus the emissions due to land use change. He then calculated that the ratio averaged ~40% using that emissions data.
Now, you have applied that 40% to a different set of emissions data. I know this because in Ian Hills graph, in 1966 the change in CO2 somehow exceeds that of the total emissions! Oh dear. Whereas, for Knorr, the change in CO2 never comes close to touching the emissions line in the graph, that’s because it is a always ~40% of the emissions data.
The emissions data that Ian Hill uses appear to be missing about 1.5Gt/y from each data point, which is approximately that of the land use component. However your change in CO2 from the Mauna Loa site is the same. Which means that your 40% is out approximately 0.6Gt/yr.
http://www.pnas.org/content/104/47/18866.full.pdf+html

What you have done is apply the AF calculated from one set of emissions data, and applied it to different (lower) set of emissions data, which is a WRONG WRONG WRONG (i.e.invalid) thing to do. No wonder the 40% doesn't match the change in CO2!

Sorry about the capitals but I wanted to get the message across.
You are all het up about a simple calculation error, but that appears to be the standard these days.

Curmudgeon:
The change in CO2 IS accelerating, in line with emissions. I think what is confusing you is that the change in emissions is already expressed as a rate (i.e Gt/y increase), and the trend, although linear is not flat, but rather increasing (i.e. positive), which means ACCELERATING. And this is even so with the data Cox espouses.

Bugsy; I will check to see whether Dr Quirk's graph is indeed a combined F-fossil+ land use change-LUC as per Canadell and not just fossil fuel emission.

LUC is 25% of F as per Figure 7.3:

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-7-3.html

If it were the case then the Gt estimation for the AF and ACO2 in Ian's graph would rise by 25%; even so it would still be below Knorr's AF graph which is 46% of F+LUC; and Knorr's AF at 46% is STILL below the atmospheric increase.

In other words Bugsy, the point would still stand.