Bishop Hill Carbon cycle: better than we thought
Oct 14, 2014 Climate: carbon budget A new paper in PNAS has been getting quite a bit of media play today, which is slightly surprising because the overall theme is "it's better than we thought". The original paper is here and there is a rather helpful "Significance" section alongside the abstract.
Understanding and accurately predicting how global terrestrial primary production responds to rising atmospheric CO2 concentrations is a prerequisite for reliably assessing the long-term climate impact of anthropogenic fossil CO2 emissions. Here we demonstrate that current carbon cycle models underestimate the long-term responsiveness of global terrestrial productivity to CO2 fertilization. This underestimation of CO2 fertilization is caused by an inherent model structural deficiency related to lack of explicit representation of CO2 diffusion inside leaves, which results in an overestimation of CO2 available at the carboxylation site. The magnitude of CO2 fertilization underestimation matches the long-term positive growth bias in the historical atmospheric CO2 predicted by Earth system models. Our study will lead to improved understanding and modeling of carbon–climate feedbacks.
The Telegraph's take is here and it's interesting to see who they have got hold of to belittle the results:
Dr Simon Lewis, Reader in Global Change Science at University College London, said: “This study shows, correctly in my view, that photosynthesis is highly responsive to carbon dioxide, but this is far from the only factor amongst many that will impact the forests of the 21st century and how much carbon they store.
Prof Peter Cox, Professor of Climate System Dynamics at the University of Exeter, said: “Avoiding two degrees of global warming is a huge challenge for humanity even if this effect is taken into account.”
Dr Chris Huntingford, Climate Modeller at the Centre for Ecology and Hydrology, said: “This new paper suggests plants are slightly better at capturing CO2 than we thought.
A little Googling shows that the diligent journalists at the Telegraph have simply pasted in these comments direct from the Science Media Centre press release, although it seems that Richard Betts' contribution didn't make the cut:
This is a very interesting paper adding to our understanding of plant physiology. The authors remark on the potential importance of their results for global carbon cycle modelling, and this is indeed relevant, but as a priority for improving carbon cycle modelling there are other processes which current models treat either very simplistically or not at all. Fire disturbance, for example, is not included in some of the models examined here – its inclusion could be more important than any improvements in modelling CO2 fertilization, as it seems likely to be an important feedback on climate change. Changes in global soil respiration at the global scale are also poorly understood.
“So while this is an interesting and useful contribution, it should be put into context with the bigger picture – disturbance mechanisms as well as physiological processes are important.”
Somewhat off message perhaps.
Reader Comments (78)
The BBC has the story here:
http://www.bbc.co.uk/news/science-environment-29601644
It starts off quite well with,'The authors say it explains why models consistently overestimated the growth rate of carbon in the atmosphere.'
Then comes this,'But experts believe the new calculation is unlikely to make a difference to global warming predictions.'
By which they presumably mean that the 'experts' will stick to their guns and keep believing their obviously incorrect predictions.
A close call for the BBC.
Gasping.
More of the expected unexpected stuff.
Conclusion, it is worse than we thought and we are running out of time.
One of the characteristics of climate 'science' is the belief that unvalidated models provide evidence, or that running unvalidated computer models with different input parameters amounts to conducting experiments.
I remember that the latter stuck in the craw of Professor Michael J. Kelly of the University of Cambridge Department of Engineering.
Its got to be Dark Matter and Dark Energy.....has to be. Well, the BBC said so last night. Hang on, they didn't.....eh?
Model frigging...not a problem at all. Need something to get the maths right.
"Fire disturbance, for example, is not included in some of the models examined here – its inclusion could be more important than any improvements in modelling CO2 fertilization, as it seems likely to be an important feedback on climate change."
Fire? I thought clear cutting the USA's forests and burning them in the UK was 'carbon neutral'? Why would Fire disturbances in the wild be any different?
The BBC b**llsh*t does get through though, in spite of reality pressing in on all sides. A forty year old builder painting my wall remarked, when a shower washed his work on to the path, how difficult it was to finish the job with all the extreme weather we have these days. I said, "It's a shower, not a hurricane." To which he replied: "Yeah, well, OK, I'll come back Friday."
The effects of higher CO2, aerial fertilization, have been found in many experiments and estimates made of the future impact. Last year Shevliakova et al. provided an estimate of the past net reduction in CO2 from past increased biosphere activity. They "estimate that enhanced vegetation growth has lowered the historical atmospheric CO2 concentration by 85 ppm, avoiding an additional 0.31 ± 0.06 °C warming."
Historical warming reduced due to enhanced land carbon uptake
www.pnas.org/content/110/42/16730.full
DB
Most encouraging. That gives us at least a decade's extra margin.
At least they highlighted that CO2 is an essential fertilizer. Its a start.
Claims that levels of CO2 in the atmosphere are increasing are not the result of some model. These are the result of observations made at monitoring stations such as Mauna Loa. CO2 concentration is currently increasing at about 2 parts per million per year. This is not a model output and this paper will not change anything in that regard.
The climate models which forecast doom and gloom (General Circulation Models) do not model the growth of CO2. They assume various scenarios of CO2 increase and calculate, not very well, the consequences for global temperatures. The scenarios are called, rather grandly, Representative Concentration Pathways (RCPs). Each RCP assumes a different rate of CO2 growth leading to different a ‘climate future’.
This paper has no impact on those projections. The nonsense will continue.
Martin A
You use the tools available.
We have increased the CO2 concentration from 280ppm to 400ppm in 130 years and are now arguing over whether the global warming and climate change that occurred over the same period is cause and effect.
On the basis of the physics the CO2 hypothesis fits better than any alternative.
Unfortunately the only way to clinch the matter empirically is by controlled trial. For that you need an identical planet to the Earth, without an industrial civilization., to act as a control.
Failing that, simulations provide virtual Earths in which to try out alternative scenarios.
Do you have a better option, something else which would help confirm or falsify AGW?
MikeB
GCMs use simple physical equations to simulate a simple physical system, with limited success.
Human CO2 production depends on economics and politics which are much !ess predictable. If you have found a successful way of simulating them, you could rule the world!
They aren't the first mainstream scientists to give us such privileged glimpses of the bleeding obvious:
http://www.csiro.au/Portals/Media/Deserts-greening-from-rising-CO2.aspx
"Increased levels of carbon dioxide (CO2) have helped boost green foliage across the world’s arid regions over the past 30 years through a process called CO2 fertilisation, according to CSIRO research."
http://earthobservatory.nasa.gov/Features/GlobalGarden/
"Leaving aside for a moment the deforestation and other land cover changes that continue to accompany an ever-growing human population, the last two decades of the twentieth century were a good time to be a plant on planet Earth. In many parts of the global garden, the climate grew warmer, wetter, and sunnier, and despite a few El Niño-related setbacks, plants flourished for the most part."
Alas the official IPCC viewpoint is that all warming must be assumed bad: They are only interested in worst case scenarios because only those will drive policy. Heaven forfend that centuries of discoveries that warmer is good and cold is bad might escape the confines of current academic pessimism. Dendroclimatology is even based on the simple truth that trees grow better in warmer climates.
The good news is coming in thick and fast as the alarmist case starts to crumble. A new paper at WUWT puts the climate sensitivity at 0.43.
It is interesting how each hammer blow to the global warming scare makes its supporters bleat louder.
EM,
You are sat on a planet that provides the control against which the models can be tested. The models aren't very good, the Earth says so.
Yes, Steve Jones (8.50am) I too spotted the BBC's 'on the one hand; on the other hand' assessement of this information:
'Yes, yes - its all jolly good that plants are taking more CO2 than we thought - but that doesn't affect the alarmist views which we've been putting out for years, because that would be to admit we were WRONG...'
EM
" We have increased the CO2 concentration from 280ppm to 400ppm in 130 years and are now arguing over whether the global warming and climate change that occurred over the same period is cause and effect.
On the basis of the physics the CO2 hypothesis fits better than any alternative."
Please provide your evidence that "we " implicitly mankind, are the SOLE cause of the atmospheric CO2 concentration rising from 280 ppm to 400 ppm since +/- 1882 CE.
In any case while there may be correlation between CO2 concentration and temperature this is no proof of cause , it could equally well be effect, or both rising CO2 concentration and temperature could result from other causes.
Get real!
I'll bet dimes for dollars that they also don't explicitly represent the effect of carbonic anhydrase in carbon-cycle models either. I haven't seen it mentioned yet in this context.
The reaction of CO2 with water to give carbonic acid/bicarbonate is not a diffusion limited reaction. It is more than a million times slower. That's why the whole of the biosphere makes copious use of carbonic anhydrase to speed up this reaction by 5 to 7 orders of magnitude.
Seawater may look like a 'wet desert' to many people. But most places on this planet are actually covered with biofilms not visible to the naked eye or casual scientist. Assuming rapid thermal- or pH-driven equilibration of CO2 at the interface with aqueous systems (especially seawater) is perilous.
That thermodynamics is not everything in a chemical system displaced from equilibrium is certainly not ignored by all. Some authors do give consideration to the effect of bio-chemical kinetics. For example, the effect of carbonic anhydrase on oxygen isotope-fractionation in calcium carbonate.
'...Experts believe that the new calculations will make no difference to global warming predictions....'
To slightly mis-quote Mandy Rice Davies during that infamous trial in 1963: 'Well, they would say that, wouldn't they..?'
EM - welcome back. You ok?
As I have said many times before, though I was by no means the first to say it, an unvalidated model is no more than an illustration of a hypothesis. I think we are in agreement there.
"On the basis of the physics the CO2 hypothesis fits better than any alternative"
I think your measure of "how well does it fit" is "is this correct in my subjective judgement?" - ie the subjective judgement of somebody who has previously been convinced of the CO2 scare story and who is therefore biased towards assessing things that seem to confirm it as likely to be correct.
"Do you have a better option, something else which would help confirm or falsify AGW?"
I would say that the GCMs, programmed by the leading experts on the subject, using the best available understanding of the physics involved, and which were stated by those experts to be the only way of reliably predicting changes to the climate, have already provisionally falsified AGW by the ever increasing discrepancy between what they predicted and what is transpiring.
" For that you need an identical planet to the Earth, without an industrial civilization., to act as a control."
I think you'd need an ensemble of identical planets. In view of the randomness involved I'm not sure that a single control planet would tell you anything - it would be like conducting a clinical trial with two patients only, one of them as a control.
EM
or may I call you Eeyore?
Falsifying AGW seems to be difficult...
DB -
Thanks very much for the link to Shevliakova et al.I noticed that the late 20th century trend of their simulations in figure 2 is reasonably close to HadCRUT3. [Bit surprised at that, didn't think anyone was still using HadCRUT3 rather than HadCRUT4; the current version is 4.3.] I looked up the model they used for that figure, ESM2G, and found that its Transient Climate Response (TCR) is 1.1 K. One can reasonably infer that the effect that the authors attribute to enhanced land CO2 uptake (0.3 K) would be considerably larger, perhaps 0.5 K, if evaluated on the other models which are more sensitive to pCO2.
Glebinkava
More complexity than your question implies. Auditing fossil fuel burn and concrete production give figures for human CO2 production approximately twice the rate of accumulation in the atmosphere. The main carbon sinks are the oceans, measurable directly and by declining pH, and vegetation. At the same time carbon sinks such as tundra peats and forests are releasing CO2 as decay and deforestation release fixed carbon.
You will find a detailed breakdown in the data section here .
EM
Oh, really? How then do you explain the temperature variations over the last couple of centuries where the CO2 hypothesis patently does not fit? Or any warm period before then?What the CO2 hypothesis does fit (and it's all that it fits) is the environental activists' requirement for any excuse to bully people into not using fossil fuels. Simple as that.
In spite of all efforts, nothing has happened over the last 200 years that cannot be explained by the natural behaviour of the earth's chaotic climate system.
Which, as far as I am concerned, is the null hypothesis. Prove me wrong.
In place of an unobtainable twin of the Earth with a higher percentage of CO2 to compare and contrast with this Earth at this time we need only examine the geological temperature record of the Earth during past periods with very much higher percentages of CO2 in the atmosphere.
Jamessp
Feel free. Though insult in debate is a poor substitute for evidence.
I tend to divide the AGW problem into a three part chain of causation.
1) The cause; carbon dioxide increase, with its consequent change in radiation budget.
2) The effect; the resulting global warming.
3) The consequences; climate change such as those listed in your link.
The human effect on CO2 concentration is well established and the numerous consequences are as you demonstrate, a potential morass of detail.
To falsify AGW you should focus on the link between increasing atmospheric CO2 and increasing global temperature, measured as the total energy in the system. This is the key issue.
The problem is that the link can be demonstrated mathematically and empirically on a laboratory scale. On a planetary scale the link can be predicted, and so far observed to match prediction, but cannot be empirically tested.
EM,
In your opinion, how long would global average temps have to flatline/decline whilst CO2 concentrations rose before you would consider AGW falsified?
This is a genuine question.
"We have increased the CO2 concentration from 280ppm to 400ppm in 130 years and are now arguing over whether the global warming and climate change that occurred over the same period is cause and effect."
It was mentioned above that the rise in CO2 neatly fits the rise in temperature from the end of the little ice age till around 2000 or so. (the 130 years)
I would like to point out that the amount of Tennessee sipping whiskey manufactured was also was increasing during this time period and could well be the cause of the increased temperatures. On the other hand, so could the increasing divorce rate, or the number of people who speak English. (I am sure everyone has their favorite --- mine is the whiskey)
I can't believe that an honest man would start near 1870 and make the claim that mankind has caused a temperature rise. Do you think the little ice age was all wine and roses? Does climate history not teach us that global temps rise and fall and have been doing so for at least a Billion years?
There is no point engaging with a troll like EM. Don't encourage him.
Martin A
The starting point for my acceptance of AGW is the Rsquared of 0.7-0.8 between CO2 concentration and temperature in recorded and paleo data. Nothing else comes close.
Auditing the carbon budget validates our contribution to increasing atmospheric CO2
There is also, thanks to a variety of workers from Tyndall and Arrhenius up to the USAF a clear physical mechanism linking the two, validated mathematically and by laboratory experiment.
The problem on a planetary scale is that we have only four suitable experiments running (Earth, Mars, Venus and Titan). These confirm the general physics of CO2 and methane as modifiers of radiation balance, but not in enough detail to validate the effect of AGW. That would require replicate planets, for which GCMs have to act as a virtual substitute.
There we seem to differ. Lacking a scientifically better alternative, as a working hypothesis I accept that final step.
You do not. I am not sure why.
Plants grow bigger with more CO2?
Cor! Who would have thought that!
Mark Stoval
Correlation is only a starting point. It only becomes significant once you can demonstrate a mechanism underlying the correlation.
For example, people wearing shorts eat more ice cream. This only makes sense when you identify that both are Summer activities. Similarly, the physics of the greenhouse effect turns the correlation between temperature and CO2 more than a coincidence.
Beware the "climate has changed before" argument. You use it to imply that humanity cannot affect the climate. This is not a logical argument.
Philip Bratby
Are your beliefs so fragile that they cannot withstand a little debate?
EM: I'm a scientist; I don't have beliefs like you seem to have.
For EM:
http://wattsupwiththat.com/2014/10/14/yet-another-significicant-paper-finds-low-climate-sensitivity-to-co2-suggesting-there-is-no-global-warming-crisis-at-hand/
Connie hedegaard once said "it does not matter whether it is warming or not, the windmills make economic sense.."
I know it is not de "bon ton" to dispute the words of an "Anointed One", in bien-pensant "progressive" circles, but I believe she should be brought to account.
An overpass or a bridge NOT built, with taxpayer's money is equivalent to "x" deaths.
Presumably, the windmills were built to save MORE not FEWER people.
If that turns out not to be the case, despite "knowing better" and ridiculing sceptics for the past 30y, then our
bien-pensants are liable to MURDER.
Never mind providing LESS, not MORE value for money to the taxpayer as promised (tantamount to THEFT)
These are the stakes, for our repainted lefties: peddling their lies a bit further OR going to prison, where they belong.
To measure the total energy and heat in the system you need to know the temperature (plus a host of other factors). You placed this second in your chain of causality. The models predicted surface warming. It hasn't happened. Switching from temperatures to measures of energy is putting the cart before the horse when it suits you.
Some proponents claimed, without good evidence, that the heat was going where we couldn't measure it: the deep oceans.
A more recent paper now claims it's gone into the upper part of the Southern Ocean. It's marvellous, isn't it? Those great wide rolling blue oceans are so vast that people can find new places to hide missing heat for a while yet.
Meanwhile, the model predictions keep on failing.
EM
I’m sorry you thought it was an insult. I’ve always quite liked Eeyore.
You say that the warming so far observed matches predictions. If so, why the apparent acceptance by climatologists that observable warming has stopped, but that it is being somehow stored elsewhere, such as the ocean depths?
So now GCMs have to model CO2 diffusion inside leaves? Well doesn't that just about take the f*cking biscuit. Next step: gnat flatulence. That should provide a few hundred more middle class rent-seekers a pretext to live comfortably at the expense of everybody else.
Presumably this paper will be used to adjust the models so as to postpone their imminent falsification and keep the gravy train on the rails a while longer.
I note that EM conveniently forgets all the fanciful feedback mechanisms required to magnify the effect of CO2 beyond its direct contribution to the 'radiative budget'.
And if this paper 'buys 10 years' before the coming biblical armageddon, how does this compare to the countless billions pissed away on windfarms and solar panels?
Entropic man,
"We have increased the CO2 concentration from 280ppm to 400ppm in 130 years and are now arguing over whether the global warming and climate change that occurred over the same period is cause and effect."
Two premises (at least) in one sentence and absolutely wrong on both. First, you state, "We have increased the CO2 concentration from 280ppm to 400ppm in 130 years..." Just accepting the fact that CO2 concentrations have increased from 280ppm to 400ppm in 130 years, you assume that all of the increase is due to humans but you cannot prove it.
Second, your statement implies that global warming was continuous over the entire period ("[we] are now arguing over whether the global warming and climate change that occurred over the same period...), which is patently not true. Just a simple review of the official historical temperature records show periods of warming and cooling, and that the magnitude and rate of warming from approximately the early 1900's to about 1940 was similar to the recent warming blamed on humans.
When your premises are false, your conclusions are wrong.
I'd like to repeat Steve Jones' question
I too am interested in the answer.
And I would also be interested to hear a proper explanation of why I should be expected to disprove someone's fanciful idea that of all the climatic variations that have happened in the past only the most recent is cause for alarm.
I repeat, EM, the climate has done nothing in the last two centuries that cannot be attributed to natural variation so why is the onus on me to prove that rather than on you to prove otherwise?
A couple of activists calling themselves scientists (or in the case of Wirth and Gore not even doing that) coming up with a bright idea that has since made them very famous and very rich does not a hypothesis make and the fact that a number of others like Mann, Jones, Briffa, Trenberth, Lewandowsky, Cook and Oreskes (who finally appears to have signed the death warrant of her own credibility) have jumped on the bandwagon does not alter the fact that climate, dear old chaotic climate, is still going her own sweet way.
Prove me wrong.
Not banned yet
The paper you referred to described a low climate sensitivity based on a climate model. (Do models suddenly become acceptable when they say what you want to hear? :-) What stood out for me was the large amount of negative forcing he assumed to be due to cloud and the large amount of variation in solar insolation. Both will probably be disputed when the paper is critiqued elsewhere.
It is the same old problem; assume low positive and high negative forcings and you get a low sensitivity. Assume the opposite and you get high sensitivity. The whole process can become too dependent on the conscious or unconscious biases of the author.
EM
"Assume the opposite and you get high sensitivity."
You also get instability (more positive than negative feedback), which is hard to square with a climate system that has remained relatively stable for millennia, despite fluctuations in CO2 and temperature that have never produced a 'tipping point'. It is perhaps no coincidence that the scientists most resistant to AGW are the geologists.
I obviously don't have your grasp of German EM, so my reaction is based on the translated abstract at WUWT which seems to be quite careful to distinguish their "model" from the IMO useless AOGCMs.
SandyS, Mike Jackson
The answer really depends on whether one accepts that the AMO/ PDO has a significant effect.
If it could be shown that there is no 60 year cycle, then the current slowdown/ pause/hiatus will move outside the 95% confidence limits for the post 1970 long term trend 20 years after it started. I regard the slowdown as starting when the GISS 5 year average flattened at 0.58C in 2002, so if it was still under 0.78 in 2022. I would accept that AGW was falsified.
If the PDO/AMO caused the 30 year slowdown between 1940 and 1970, then a repeat between 2002 and 2032 would not be surprising. If it were shown that the 60 year cycle does have a +/- 0.15 effect then the date would move back to 2032.
I think that defines my boundary conditions. If the GISS 5 year average is less than 0.78C by 2022 I will be wondering. If it is still below 0.78C in 2032 I will be convinced.
Sorry about the complex answer.
EM
"More complexity than your question implies. Auditing fossil fuel burn and concrete production give figures for human CO2 production approximately twice the rate of accumulation in the atmosphere."
There is also more complexity than your response implies! The fact that human CO2 production is approximately twice the rate of accumulation in the atmosphere is no way proof that human production of CO2 is the CAUSE of the accumulation much less the increase in Temperature.
CO2 annual fluxes between ocean and atmosphere, ocean and atmosphere, ocean and biosphere, atmosphere and biosphere, sediments and atmosphere, atmosphere and sediments ( weathering), volcanoes and ocean and volcanoes and atmosphere are estimated, at the very minimum to total in excess of 310 Gigations/year ( ie excluding the volcanic component which is essentially unmeasured - especially the submarine emissions), while fossil fuels,cement etc. total a paltry 7.1 Gigations/ year.
The level of human emissions is thus about 2.3% of the non human CO2 flux and almost certainly within the error of estimation of the non human fluxes.
If you are looking for correlation there is a really good one between the adjustments made to the temperature record and the atmospheric concentration of CO2 (Correlation coefficient 0.98).