2011-06-14 18:58:41Essenhigh 2009 (Residence Time)
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

 

Hi all, I have written a draft of a comment on the paper in the journal Energy and Fuels by Robert Essenhigh that claims the short residence time of atmospheric carbon dioxide means that anthropogenic emissions are not the cause of the post-industrial rise in atmospheric carbon dioxide.  You can find the original paper here:

http://pubs.acs.org/doi/abs/10.1021/ef800581r

I'd be very grateful if anyone has the time and energy to read it and give constructive criticism.  I am hoping to submit it to the journal once I hear back from Prof. Essenhigh, but I will also rewrite the paper as an advanced rebuttal/swiss cheese article for SkS.  The paper is not submitted yet, so please do not distribute it beyong SkS authors.

You can download a draft from

http://theoval.cmp.uea.ac.uk/~gcc/ef2010a.pdf

many thanks in advance

Gavin

2011-06-15 09:28:04
Riccardo

riccardoreitano@tiscali...
93.147.82.165

I do not have access to Essenhigh's paper, I think I hould read it before commenting on your. Please send a copy to riccardoreitano@tiscali.it

Will you submit the paper to the same journal?

2011-06-15 14:49:19
Andy S

skucea@telus...
66.183.170.32

Judging from the abstract only, it baffles me how a paper like Essenhigh's could have passed peer review. 

I don't understand how he can rule out an anthropogenic source and then suggest an unknown natural source due to "rising temperatures". How big is this natural source and would it not also be subject to the same residence time considerations as the anthopogenic source? Surely his argument is not against an anthropogenic carbon input but a carbon influx of the same magnitude from any source?

How about the carbon isotope ratios; the drop in atmospheric oxygen; the coincidence of the atmosphic CO2 rise and the burning of fossil fuels' the absence of anything remotely like this recent increase in the ice-core records of interglacial periods?

Are you aware that Essenhigh's paper paper and others like it were rebutted rather harshly by the EPA (pages 1-4)? Albeit without your mathematics.

I have done a quick read and have made a handful of comments on the pdf of your MS if you are interested.

2011-06-15 17:14:10
Glenn Tamblyn

glenn@thefoodgallery.com...
58.170.210.239

Essenhigh, and also Tom Seglstad, bang on with the same idea and they are a favorite in some parts of the denialosphere.

 

There reasoning is fundamentally faulty because they assume that 14CO2 changes will give you an insight into overall CO2 changes. Their logic is all wrong. They fundamentally ignore the fact that there is a continuous flux of CO2 from Air to Ocean AND from Ocean to Air. These fluxes alone will balance the 14C ratios over time even if the two fluxes exactly balance each other.

If I have two large silos of grain, A &  B, each holding a trillion grains of wheat. In one I have 1 stray grain of rye while in the other 1000 stray rye grains, and these are well mixed in both silo's. Then I start transferring grain between both silos A -> B and B -> A such that the two transfer rates are the same. Over some time period the quantities of rye in each silo should equilibrate at 500 grains each. And I could determine a time constant associated with this.

However this tells me nothing about the total flow of grain between the silo's or whether they are in balance or not.  I could just as easily use a filter in each silo to filter out the rye and whenever I find a grain toss it into the other silo. The concentrations of rye would still equilibrate but there is no flow of the wheat at all.

I cannot determine the NET flow of wheat between the silos by looking at the rye concentration.

What matters is the relative bulk flow rates of all forms of CO2 Air<--> Ocean. And this is driven by a much slower process. In its simplest form Henry's law defines the equilibrium that will eventually be reached but there are 2 complications. Firstly since the oceans are very slow to mix, additional CO2 added to the oceans at the surface from the atmosphere takes time to mix into the broader ocean volume. In the mean time CO2 partial pressure in the surface waters grows quickly and a localised equilibrium due to Henry's law is approaced even though the total ocean volume is nowhere near this equilibrium. Mixing to the deeps then becomes the limiting speed factor.

Also, equilibration between atmospheric and ocean CO2 isn't governed by just Henry's law. Since solution of CO2 in water is an example of a chemically buffered solution, this has to be tajken into account. CO2 reacts with water to produce Carbonic acid. This then engages in reactions witj Carbonate and Bicarbonate ions in the ocean (Boron also plays a part in this via Borate ions) in a complex chemical equilibrium. The balance between aqueous CO2, Carbonate & Bicarbonate then reaches a chemical equilibrium. Adding CO2 to the water changes this equilibrium so that the CO2 aqueous component is artificially inflated by a  factor of 10 or so. This slows the movement towards equilibrium due to Henry's Law.

So two different processes slow the equilibration rate. Essenhigh ignore or reject these. If they are ignoring them, then they are ignorant. If they reject them they need to give grounds.

 

2011-06-15 19:15:48
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

Riccardo, I can send you a paper copy (let me know the address via email - my email address is on the paper) and I'll drop a copy in the post.

I am indeed going to submit the comment to the same journal (I have been in touch with the journal editor to discuss it already, and have been discussing it with Prof. Essenhigh)

2011-06-15 19:21:11
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

Andy S, I agree it is surprising it made it through peer review, it certainly wouldn't have got past the reviewers of a climate journal, but Energy and Fuels is to do with the science of combustion, so it might be difficult to find reviewers with a good knowledge of the carbon cycle.

The jump from "short residence time" in the paper to "the rise is natural" is not really explained. I think the origin of the argument is that anthropogenic emissions are timy compared to natural ones, hence a natural rise is feasible even with a short residence time,  However this ignores the fact that natural uptake is even larger.

Thanks for reminding me about the EPA, I ought to include a reference to that.  I'd be very happy to recieve any comments on the paper, I would like to get this right!

2011-06-15 19:25:41
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

Glen, yes, the use of the residence time argument in the blogsphere is the reason I am sending in a comment paper to the journal.  A peer reviewed rebuttal of the argument ought to be enough to surpress this argument.  The funny thing is that the anthropogenic origin of the rise in atmospheric CO2 is pretty much the only thing we know in climate change with no doubt at all.  The mass balance argument proves beyond any doubt that the rise cannot be natural.  The skeptics do themselves no favours at all by raising the residence time argument.

Hopefully the informal arguments in the paper and the simulations, using the same kind of models that Essenhigh used, will be enough.

2011-06-16 09:09:32
Riccardo

riccardoreitano@tiscali...
93.147.82.152

Gavin
I find your paper much cleaner than Essenhigh's. The latter is a bit confusing, unduly complicated and apparently based on the misunderstanding of what the adjustment time is. I think you're really spot on, though I'm not sure you need the discussion on the airborne fraction. You may consider to leave it out. Below a few other points you might want to consider.

- you may derive the residence time first and then the adjustment time. In this way you show that you reproduce Essenhigh's results and go further to the proper description and derivation of the adjustment time.

- you may quote the several CO2 decay times (note a in table 2.14) to compare with your 74 yrs.

- shouldn't you add in eq. 7 the term Fa to be more general?

- pag. 20 near the end, you may underline that the use of 14C by Essenhigh gives the residence time, not the adjustment time.

Few typos/improvements:

- pag. 5, end of the paragraph below eq. 2: dC/dT => dC/dt

- fig. 2: use the same notation as in the text

- pag. 8, first paragraph: "Figure Figure 1" => "Figure 1".

- Same paragraph "Fss = 190.2 Gtc Y R−1 , ∆Fi = a20 GtC yr−1" => "Fss = 190.2 GtC yr−1 , ∆Fi = 20 GtC yr−1"

- pag. 19, paragraph below eq. 8: you solve eq. 7 but refer to eq. 8

- fig. 7a: lines almost invisible

2011-06-17 17:19:26
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

Thanks Riccardo, I'll be re-editing the paper next week once anyone who wants to comment has had a chance to do so.  Many thanks to all those who have commented so far, it is much appreciated!

 

Gavin

2011-06-19 09:35:06
Riccardo

riccardoreitano@tiscali...
93.147.82.71

After your comment gets published I think that, leaving the debunking of Essenhigh aside, it could be a good didactic post on residence vs adjusted time. I plan to write one for an italian blog anyway. Please let me know when the comment will be published.

2011-06-23 22:46:29The die is cast; I have crossed the Rubicon
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

well I have submitted the paper to Energy and Fuels anyway ;o)

Many thanks to all of those who have sent me comments; they were all useful, even if I didn't include all of them.  Let's see what the reviewers say!

2011-06-24 06:35:07
Riccardo

riccardoreitano@tiscali...
93.147.82.69

I'm confident it will get published. Good job.

P.S. I tried to reply to your email but for some reason it kept bouncing back with a failure notice.

2011-06-24 17:24:14
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

Cheers Riccardo, I'll mention the email failures to our sys-admin to see if it is at our end.

2011-08-07 15:07:33
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
68.109.193.174

Good news, the paper has been accepted by E&F.  The reviews are very positive, however a couple of the reviewers request a few additions that I could probably do with some advice on.  Hopefully I can start work on it next week.  Many thanks to all those who commented on the first draft, much appreciated!  

The paper may also be of some use in addressing the forthcoming paper by Salby.

2011-08-11 20:02:29
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.71.146

Congratulations mate! 

2011-08-11 20:14:15
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

Cheers Rob, Salby next? ;o)

2011-08-11 21:34:17
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.71.146

Sounds good to me.

2011-08-12 09:51:51Congrats from me also
John Cook

john@skepticalscience...
124.177.173.40
Only just noticed this thread (my excuse is I was on holiday when you announced the good news). Congrats, great news and very useful to have this in the literature whenever a denier cites Essenhigh. Will be very cool to use a version of your paper as the advanced rebuttal and it wouldn't hurt if we revisited the Basic/Intermediate versions also.
2011-08-12 23:23:32
Dikran Marsupial
Gavin Cawley
gcc@cmp.uea.ac...
139.222.14.107

cheers John.  I have started an advanced rebuttal of the residence time post, and may do a supplementary blog post on Essenhigh's paper going over some of the more subtle points I left out of the paper.