What a convoluted argument to justify a predetermined position. This 'theory' would seem to suggest a lot of CO2 should have been absorbed by the strong La Nina. Yet a week or two ago we had record temperatures. The theory needs more tinkering. Perhaps it could explain where the missing socks go to.

Taswegian; the 2nd last paragraph sums up what is not a "convoluted" argument. Even more simply put: the AF is ALL humans can be contributing to the increase in atmospheric CO2 but the atmospheric CO2 is increasing MORE than the AF; therefore nature MUST be contributing to the increase.

Perhaps it's convoluted because it doesn't suit your belief in AGW?

Anthony,
Lung cancer appears to cause more death than men smoking

Before commenting, I would like to you to please clear up for me what appears to be two different concepts of what the airborne fraction (AF) is.

Is it the percentage of anthropogenic emissions that stay in the atmosphere? (i.e 40% of human emissions stay in the atmosphere)

OR
Is it the percentage of the CO2 increase that is anthropogenic in origin?
(i.e. 40% of the increase is anthropogenic in origin)

It appears to me that Knorr is arguing the first, but the second last 'summary' paragraph appears to argue the second, but that also seems to be contradicted by the final figure.

Could you please clear this up for us?

Taswegian
Its not a convoluted argument at all, but they are covering their bases. In essence what they are saying is that concentrations of CO2 in the atmosphere appears to bear no correlation with increases in emissions. The first is plugging away (at 2 ppm per year, about) while the other is increasing. At the least there is clearly a mismatch. So what's happening? I don't think recent summer temperatures are all that relevant to the argument. The problem is that forecast increases in temperatures (much higher than present) require big increases in CO2 in the atmosphere which doesn't seem to be happening.

Bugsy
Not quite sure what they mean by AF in that last part but the point they are making is as per my response to Taswegian. The fraction of industrial CO2 staying in the atmosphere seems to be much less than required by the theory.. we should be seeing much higher concentrations of CO2 by now.. so what's happening? the point's been made a few times over the year but largely ignored by the global warming industry. There's been no response, so there's been no pat answer. The point's just been ignored.

Interesting - potentially. Is there anything to suggest this information and analysis has any scientific credibility?

I followed several links in the article (not all of them, by any means), but the following is typical of what I found.

http://wattsupwiththat.com/2010/12/26/co2-ice-cores-vs-plant-stomata/

an article by a David Middleton, who is described as follows (I couldn't find anything about his scientific qualifications)

About David Middleton
I have been a geoscientist in the evil oil and gas industry for almost 30 years. My favorite hobby is debunking the junk science of the radical environmentalists...Particularly the junk science of anthropogenic global warming.

Hardly a source of choice for trustworthy scientific information.

Next I followed a link to http://joannenova.com.au/
There is a lot of information about this lady at
http://joannenova.com.au/about/

Conspicuous by its absence was anything about her scientific knowledge about climate change.

For the benefit of those like me who can't spend all day hunting for any scientific research from reputable sources (eg published research) backing this up, could you indicate where it is (if any)? (Again, I acknowledge that I haven't followed up all the links in the article - there are too many - I just want ones to reliable scientific research).