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Carbon cycle: better than we thought
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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)
Mike Jackson
Always the same logical fallacy. Past climate changes such as the LIA or glacial pwriods can be linked to past natural changes in vulcanism, insolation or orbits. This does not preclude the possibility of anthropogenic effects.
Past climate changes can be linked to past causes; vulcanism, insolation, orbits etc. The problem with the 20th/21st century warming is that the natural changes should be producing long term cooling. There is a slow Milankovich cooling trend, above average vulcanism and a weak Sun by 20th century standards. There is even a lot of industrial aerosol pollution pushing temperatures down. The only warming forcing is CO2, which is probably anthropogenic.
Despite this, current temperatures match or exceed the Holocene peak and the temperature datasets all show ongoing warming during a supposed pause.
If your naturally driven hypothesis were correct, you would be able to link the observed warming to natural mechanisms. Since the mechanisms are driving temperatures in the opposite direction to the observations, your hypothesis is incorrect.. What will you put in its place?
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Jamesp
The fourr strange attractors for Earth's climate are hothouse(5C warmer), interglacial (present temperatures), glacial (5C cooler) and snowball (10C cooler).
I would not regard a climate which has varied through 20C in last 700 million years, 15C in 2 million years, 5C in 12,000 years and 0.8C in 130 years as particularly stab!e.
We have increased? Just who or what are you including in that increase? 'We' do expect explicit definitive and proven observations defining all portions that comprise 'we' and their contributions.
CO2 atmospheric percentage fluctuations are quite normal and mankind's contribution are natural changes.
What a vague statement of nonsense.
Exactly what CO2 hypothesis are you referring to? Again, be explicit, be definitive, be illuminating at least for once.
Oh? You mean scientists can not provide a plan for definitive CO2 controlled trials?
Seriously? And you actually believe that?
What simulations are you referring to that provide 'virtual earths'? Not one of the GCM models attempt to simulate Earth. Every GCM is some programmers idea of how to replicate and produce the calculations some researcher desires. Not one model strives to actually 'simulate' any Earth function.
Unless, you mean 'simulate' as represented by the first portion of the definition for simulate;
---1: to give or assume the appearance or effect of often with the intent to deceive : imitate.
Macro Thermodynamic, you infer that CO2 is dependent on economics and politics and this is cause for the failure of the GCMs? Instead of program certification, validation or a full run of engineering validation tests?
Whatever happened to the 'global' atmospheric content or does CO2 slipping up a part per million and then slipping down a part per million confuses the models and model makers?
Besides, that CAGW party line where four molecules of CO2, (molecular weight 44.0095 X 4 molecules CO2 = 176.038, per 10,000 atmospheric molecules), manage to trump most effects on the atmosphere and cause significant and long term energetic excitation to 9,996 other air molecules resulting in the dreaded AGW temperature rise.
Atmospheric contents that are mostly composed of;
A) Nitrogen (N2, 14.0067 X 2 = 28.01340) roughly 3,904 molecules of N2, (78.08%), total weight 109,364.3136g/mol
B) Oxygen (O2, 15.9994 X 2 = 31.9988g/mol) roughly 1,407 molecules of O2, (20.95%), total weight 33,502.7436g/mol
C) Water (H2O, 18.01528g/mol) varies between 0% - 4%, 0 to 7,206.112g/mol.
D) Argon (Ar, 39.948g/mol), roughly 93 molecules of Ar, (.93%), Total weight 3,715.164 g/mol.
E) Carbon Dioxide (CO2, 44.0095g/mol), roughly four molecules of CO2 (.04%), Total weight 176.038g/mol
F) Others not included for brevity
Rough estimate of molecular weight per ten thousand molecules of atmosphere, minus water: 146,758.2616 g/mol
Rough estimate by weight CO2 per ten thousand molecules of atmosphere, minus water: 176.038 g/mol
Percentage of CO2 by weight: .11995%
CO2 is a greenhouse gas. That is, CO2 captures certain bands of radiation and re-radiates the energy; or because CO2's higher excitation level after absorbing an emission photon the CO2 molecule interacts with other molecules...
Now explain exactly how those few molecules of lightweight CO2 cause all of those other molecules and their total molar weight to go up in temperature?
Explicitly, of course; after all you're claiming the thermodynamics avatar.
The first thing which occurred to me was the (probably daft) idea that if they were saying that more CO2 was being absorbed than they thought, then the rump of it was causing all the warming. The effects on TCR etc would, of course, means that 'it's worse than ever'.
Special and general relativity are both approx. 100 years old. Both have been subjected to endless experiment and, within defined boundary conditions, produce extremely accurate results. The assault on Einstein's theories have been relentless and ruthless and yet they are still regarded as theories.
AGW comes along 20 years ago and its proponents claim it is watertight against a backdrop of predicting nothing. Furthermore, no debate or questioning of the central tenet is allowed.
Quite a contrast.
Ah yes, EM continues their mission of uselessness:
"...Past climate changes such as the LIA or glacial pwriods can be linked to past natural changes in vulcanism, insolation or orbits...
Maybe they can be linked, but they have not yet been linked. All claims so far are drivel and fail to produce solid evidence.
The orbital theory looks good on paper, but where are the defining works that actually correlate present day temperatures to orbital cycle? None of the volcanism claims withstands scrutiny stronger than 'palsy walsy-review'. Insolation links are assumed and still unproven.
"...There is even a lot of industrial aerosol pollution pushing temperatures down. The only warming forcing is CO2, which is probably anthropogenic..."
Nonsense!!
Glebekinvara already demonstrated that most CO2 is not anthropogenic in origin and industrial pollution is extremely regionalized to small regions, most of the world is not experiencing much aerosol pollution.
"... The problem with the 20th/21st century warming is that the natural changes should be producing long term cooling. There is a slow Milankovich cooling trend, above average vulcanism and a weak Sun by 20th century standards..."
First have you actually viewed the long term temperature graph? http://www.oldearth.org/curriculum/history/65_Myr_Climate_Change.png
Earth is at the cold end of that graphs! Meaning it was usually much warmer!
Holocene optimum was cooler? Not by several degrees C it was not!
http://www.oldearth.org/curriculum/history/Holocene_Temperature_Variations.png
Forget the recent 'proxies' adlib trying to imply that temperatures since 2004 (graphs last current date) have skyrocketed when temperatures have been in a plateau.
By any stretch of imagination, Earth is in a rare period of tepid temperatures. We fear a return to colder temperatures!
You've thrown a lot of spurious CAGW gossip and disinformation around, perhaps you'll try some science?
The response of the climate committed to reports like this is amazing. Even though there are massive problems with their models and the climate predictions have failed. That ice, warming, slr, oh, pH, weather, etc. are not acting as predicted. None of it doesn't matter because they are still right and we still have to do what they demand. What utter drooling jerks..
As you know EM, I very rarely respond to trolls, but for your education, I will make an exception.
I'm fascinated that you believe that "the physics" supports the premise that a CO2 concentration from 280ppm to 400ppm results in 1, 2 or 3C, or whatever your blessed models vomit out.
Why not read Rothman, D.H. (2002) Atmospheric carbon dioxide levels for the last 500 million years
Proceedings of the National Academy of Sciences 99 (7): 4167-4171?
You will find that [CO2] has varied from 200pppm to at least 7000ppm whilst average global temperature has varied by about 10C.
Do the maths- for a 200ppm rise in [CO2] you are looking at about 0.3C- that is assuming that [CO2] drives temperature.
However Rothman concludes "The resulting CO2 signal exhibits no systematic correspondence with the geologic record of climatic variations at tectonic time scales".
Zippo, zilch.
ATheoK
Thankyou for your support. Other obligations kept me occupied yesterday evening so I didn't have the time to make another attempt at rebutting EM's logical fallacy.
At least he did reply to me this time even if he failed (as he usually does) to address the substance of the argument.
It is the most curious logic: “We admit that all our models are wrong in almost all aspects, and, while none agrees with any of the others, they are the only models that we do have, so they must all be correct.”
This is present day science? That rumbling you hear is not the earth-tremor resulting from fracking for gas, it is the sound of every scientist in history spinning in their graves.
One has to love sophomores and their logic/reasoning. They hate coal. Coal is mostly the CO2 residue from plants. Billions of tons of the stuff. At our meager ppm CO2, it'd be trillions of years before a tiny seam of coal was laid down. Then there's all those other "fossil fuels" alledgedly sucked out of the air by plants and using the middleman of dinosaurs or such.
It woudl be really funny, as sophomores tend to be, but for the folks that seem to believe their foolishness. As in France heading on the track to eliminate half their zero-CO2 producing nuke plants in order to meet the EU target to reduce CO2 emissions. All to save the planet. If everyone follows the Greens, Earth will become exactly like the Moon or any of a number of lifeless asteroids.
My quote was used in the Daily Mail.
Not used in the Guardian but used in the Mail? You're a non-person you are, mate.
Entropic Man, the issue is CAGW, not AGW. The original CAGW theory was that global warming was caused by man made CO2 and was so severe and inevitable that it would overwhelm all other warming/cooling, natural or not - otherwise CAGW couldn't be predicted to be "catastrophic".
The historical record shows that people like you insisted (and you still support this) that "we" had to do something pretty damned fast about CAGW, now renamed "Climate Change" (which you still believe occurs because of catastrophic man made global warming).
Yet the global temperature has been trend stationary for well over a decade (as you admit). Consequently the CAGW theory as defined is false, and AGW appears only as a minor component of the many influences on global temperature.
In the meantime the politicians are wasting vast amounts of money filched from taxpayers like me to "tackle" something which is so insignificant it can be overwhelmed by other extant factors. I am not in favour of people like you who encourage politicians to waste money so recklessly on false premises. Effectively you, and others like you, are responsible for defrauding the taxpayer.
EM:
"Lacking a scientifically better alternative, as a working hypothesis I accept that final step."
Good point made, EM: this is the/your decision point. With a working hypothesis, you go forward. As a skeptic, however, I look at the consequences of going forward, using, ironically enough, the same Precautionary Principle that I suspect you also support. The consequences of socio-political-economic life of our fossil-fuel, energy-intensive civilization are so alarming with a demonized CO2 AT THIS TIME, that I am forced to step back from action based on the by-ignorance recognition that this hypothesis is correct.
Using a working hypothesis for further investigation is simply good science, engineering and social management. Putting the WH as a reason to act as if the WH is a proven, nailed-down fact, which it is not (and is the reason our entire argument on CAGW is model, not observation driven!) is not good in any area due to the significant negative consequences that nobody, not even the alarmists, deny.
Actually Rothman's numbers match the theory pretty well.
You will be familiar with the basic formula for calculating direct forcing with extra CO2; deltaf=5.35ln(C/Co)
Plug in Rothmans maximum and minimum CO2 concentrations and the calculation becomes 5.35ln(7000/200)=19.02W/M2.
At the IPCC's 3.8W/C that is a temperature change of 5.00C.
Assume a climate sensitivity of 2.0, well within the error bars of Nic Lewis' recent estimate. That gives an expected rise with feedbacks of 10C.
Rothman's range of 200ppm to 7000ppm for CO2 with a temperature range of 10C matches the physics well.
Budgie
I am not sure how you define catastrophic.
Dale County, Florida is 4 ft above current sea level. Sea level on the Florida coast has risen 1cm/ year since 2008 . Each high string tide pushes seawater up through the sewers into the streets. In the not-so different future the county will become uninhabitable. Does this count as a catastrophe?
Bangladesh is a larger version of the same problem. What proportion of its population have to evacuate before it becomes a catastrophe?
I do accept a 12 year pause in the land/ocean global temperature record. Unfortunately other measures such as ice melt, ocean heat content and sea level rise show that warming, expressed as accumulating extra energy, continues as fast as before. This indicates that the pause is a blip and not a long term change in trend.
Your final paragraph is about politicians is outside my competence.
Doug Proctor
Observation
My car engine is making a funny noise.
Hypothesis
The timing belt is worn.
Do you
1) Pay the upfront cost of fitting a new belt.
2) Wait till it breaks and pay the much higher cost of a new engine.
I am advocating the AGW equivalent of option 1). You are advocating 2)
The difference between us may be in our estimates of the short term and long term costs. I see lower short term coats and larger long term costs than you do.
The real problem is in the lag. If the science is correct, current conditions reflect the CO2 content 30 years ago. The effect of current CO2 levels will appear in 2044. Humanity as individuals and as a civilisation tend to value short term savings over long term costs, especially if the latter is uncertain.
If you are correct, you have maintained living standards with no long term cost. If I am correct you have maintained living standards now at the expense of considerable damage over time. That is the bet, and lacking certainty it is a bet between two different possible outcomes.
A child will choose one sweet now over two sweets in 20 minutes time, and in some ways we never grow up. :-)
I would check the timing belt, then you would know if it needed replacing.
Steve Jones
On my car, by the time you have uncoverd the timing belt you have already done 90% of the work. May as well change it.
My intended point was that uncertain outcomes should be met pessimistically rather than optimistically.
Entropic you know about as much about the mechanics of car engines as you do about the mechanics of the planetary atmospheric system.EM ever wondered why you keep getting stitched up by your local car mechanic.Bet they love you at your local garage "oh here comes muggins in his Eco Friendly Prius with his credit card what does he think hes got wrong with it this time".
Got a noise under the bonnet at least look under the bonnet if you know where the release catch is or perhaps better still get down on your hands and knees and look under the car and see what it is you ve been dragging along for the last 3 miles .Maybe perhaps make sure all the doors and the boot and the sun roof and all the windows are all shut properly try the common sense simple things first.
Perfectly illustrates Climate Change dogma prepared to waste lots of money on something too vast and too complicated to understand and you,re obviously a very clever man but you re too proud, too blinkered and just too smug to admit too.
Entropic if you,ve ever had to change a spark plug or a set of HT leads, a distributor cap ,an oil filter without making a mess or an alternator, simple stuff like a front tyre ,a battery or an off side head lamp you don't start dropping off gear boxes and clutches and taking crank shafts apart or pay a mechanic £400 just because you thought you heard a funny noise.
Entropic no bloody wonder the UK will be having power cuts this winter because we got idiots like you in charge of our energy policy who too probably don't know the difference between a fan belt and a timing belt and what a fan belt is connected too.
Mechanical metal bearings they wear first and where the funny noises usually come from.
Entropic do you think that maintaining an offshore 500 foot high wind turbine is all free electricity and only needs a bit of WD40 on the gearbox.Entropic do you honestly fancy yourself as the Fred Dibmah of renewable energy.Even silly old Fred used fossil fuel for his old vintage traction engine exhibits.
And for your information Entropic you only change the Timing Belt after 15 or sometimes every 25 /40 thousand miles as recommended in the owners hand book because its 4 hours of labour to jack the engine up change the worn Timing Belt and then tune the car afterwards or else otherwise you've blown the engine to bits.
Observation
My car engine is making a funny noise.
Hypothesis
The timing belt is worn.
Do you
1) Pay the upfront cost of fitting a new belt.
2) Wait till it breaks and pay the much higher cost of a new engine.
or
3) Find out if the timing belt is the problem.
Whenever I have the patience to write up a reply Mike, which isn't very often. You and a few others here normally do the yeoman's work answering troll circular logic.
Now the thermodynamic misery is comparing car noise to 'worn timing belts' and the idiotic CAGW precautionary principle where they want to waste our money for their fears.
Now, after many years and many cars whose engines have timing belts I do confess curiosity to Thermo-man's theoretical problem.
I've never heard timing belts making 'funny noises'. Long before timing belts 'make noise' engines have difficulty running. So the EM makes up another endlessly circular logic conundrum where EM knows the correct solution but absolutely no-one else has a clue because their engine diagnosis methods follow engineering standards.
I've even spent considerable time during the early 70's maintaining a Triumph Herald, which if any engine should have made timing belt noise that Herald's little overworked forty horsepower four cylinder should have. I never did understand why Triumph gutted the lovely Spitfire engine before sticking it in the Herald.
So EM; What do noisy timing belts sound like? Is it a whirr? Or maybe a schhiss?
ATheoK
You get an increase in white noise and vibration as the belt degrades, followed by complete silence and a ruined engine. It happened to me on a motorway in 2004.
Don't get hung up on timing belts. My point is that by delaying a decision on AGW you lose the opportunity to correct the problem before it becomes serious.
Timing belts have scheduled maintenance checks during a vehicles major service milestones. They rarely fail prematurely.
Perhaps you are referring to a serpentine belt failure? Serpentine belts are easy to check and more likely to cause noise that a driver can hear.
Conflating issues and consequences is a hallmark trait of CAGWsters.
Proper observation (definitive fact finding) performed at regular intervals would ensure that neither a serpentine belt nor a timing belt would've failed. Cost for 'maintenance' is minimal while cost for engine trauma recovery is severe.
Precautionary actions required for definitive facts that are easily verified by anyone interested can then be discussed communally or individually. Unverified or impossible to verify information never requires communal action or costs; individuals are always free to act alone.
CAGW is built on faith not facts.
EM "Actually Rothman's numbers match the theory pretty well."
Really?
We are been told that [CO2] doubling, fromm preindustrial (280-560ppm), could result in a global temperature increase of 4-6C- and possibly higher.
Rothman shows that a [CO2] increase of over 30X had NO discernable effect on global temperatures.
That said I believe that the time resolution of the study was too crude to show some of the more subtle effects.
However, assuming [CO2] has an effect then 10C temperature range and a 30X [CO2] range suggests 0.3C/doubling.
Don Keiller
0.3C/doubling is too low. A 30x iincrease in CO2 is five doublings.
An increase of 10C is therefore 2C/doubling, right on Otto et al's estimate for climate sensitivity and within the IPCC AR4 range.
Note that the IPCC senaitivity range has been between 1.5C and 4.5C/doubling.with only minor variation since AR1. Rothman's numbers at 2C/doubling agree. I am rather puzzled. Where were you told to expect 6C/doubling, or get 0.3C/doubling?
Entropic Man said: "Budgie, I am not sure how you define catastrophic."
Obviously you didn't read what I wrote. I defined "catastrophic" in my comment in the same way it was defined by CAGW supporters like you: "The original CAGW theory was that global warming was caused by man made CO2 and was so severe and inevitable that it would overwhelm all other warming/cooling, natural or not - otherwise CAGW couldn't be predicted to be "catastrophic"."
Whether the pause is "a blip" or not is irrelevant, and unproven. The "pause" certainly shows that the global temperature rise predicted by people like you to be locked to the rise in CO2, has not occurred for over a decade. Other factors can therefore overwhelm AGW, so AGW is not inevitably catastrophic, and is merely one factor affecting global temperature.
It is precisely the global warming catastrophe predicted by people like you that has driven the political reaction of spending many £billions recklessly and needlessly to supposedly "tackle" a catastrophe that does not exist. You cannot wash your hands of that responsibility, as you attempt to do. You could, however, ameliorate the damage people like you have done, by persuading politicians to reverse their policies.