Controversial new climate change results
University of Bristol Press release issued 9 November 2009
New data show that the balance between the airborne and the absorbed fraction of carbon dioxide has stayed approximately constant since 1850, despite emissions of carbon dioxide having risen from about 2 billion tons a year in 1850 to 35 billion tons a year now.
This suggests that terrestrial ecosystems and the oceans have a much greater capacity to absorb CO2 than had been previously expected.
The results run contrary to a significant body of recent research which expects that the capacity of terrestrial ecosystems and the oceans to absorb CO2 should start to diminish as CO2 emissions increase, letting greenhouse gas levels skyrocket. Dr Wolfgang Knorr at the University of Bristol found that in fact the trend in the airborne fraction since 1850 has only been 0.7 ± 1.4% per decade, which is essentially zero.
The strength of the new study, published online in Geophysical Research Letters, is that it rests solely on measurements and statistical data, including historical records extracted from Antarctic ice, and does not rely on computations with complex climate models.
This work is extremely important for climate change policy, because emission targets to be negotiated at the United Nations Climate Change Conference in Copenhagen early next month have been based on projections that have a carbon free sink of already factored in. Some researchers have cautioned against this approach, pointing at evidence that suggests the sink has already started to decrease.
So is this good news for climate negotiations in Copenhagen? “Not necessarily”, says Knorr. “Like all studies of this kind, there are uncertainties in the data, so rather than relying on Nature to provide a free service, soaking up our waste carbon, we need to ascertain why the proportion being absorbed has not changed”.
Another result of the study is that emissions from deforestation might have been overestimated by between 18 and 75 per cent. This would agree with results published last week in Nature Geoscience by a team led by Guido van der Werf from VU University Amsterdam. They re-visited deforestation data and concluded that emissions have been overestimated by at least a factor of two.
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Here is the abstract from GRL:
Several recent studies have highlighted the possibility that the oceans and terrestrial ecosystems have started losing part of their ability to sequester a large proportion of the anthropogenic CO2 emissions. This is an important claim, because so far only about 40% of those emissions have stayed in the atmosphere, which has prevented additional climate change.
This study re-examines the available atmospheric CO2 and emissions data including their uncertainties. It is shown that with those uncertainties, the trend in the airborne fraction since 1850 has been 0.7 ± 1.4% per decade, i.e. close to and not significantly different from zero. The analysis further shows that the statistical model of a constant airborne fraction agrees best with the available data if emissions from land use change are scaled down to 82% or less of their original estimates. Despite the predictions of coupled climate-carbon cycle models, no trend in the airborne fraction can be found.
Knorr, W. (2009), Is the airborne fraction of anthropogenic CO2 emissions increasing?, Geophys. Res. Lett., 36, L21710, doi:10.1029/2009GL040613.
According to Pat Michaels at World Climate Report:
Dr. Knorr carefully analyzed the record of anthropogenic CO2 emissions, atmospheric CO2 concentrations, and anthropogenic land-use changes for the past 150 years. Keeping in mind the various sources of potential errors inherent in these data, he developed several different possible solutions to fitting a trend to the airborne fraction of anthropogenic carbon dioxide emissions. In all cases, he found no significant trend (at the 95% significance level) in airborne fraction since 1850.
(Note: It is not that the total atmospheric burden of CO2 has not been increasing over time, but that of the total CO2 released into the atmosphere each year by human activities, about 45% remains in the atmosphere while the other 55% is taken up by various natural processes—and these percentages have not changed during the past 150 years)
Here is Figure 1 from the Knorr paper:
Figure 1. The annual increase in atmospheric CO2 (as determined from ice cores, thin dotted lines, and direct measurements, thin black line) has remained constantly proportional to the annual amount of CO2 released by human activities (thick black line). The proportion is about 46% (thick dotted line). (Figure source: Knorr, 2009)
The conclusion of the Knorr paper reads:
Given the importance of the [the anthropogenic CO2 airborne fraction] for the degree of future climate change, the question is how to best predict its future course. One pre-requisite is that we gain a thorough understand of why it has stayed approximately constant in the past, another that we improve our ability to detect if and when it changes. The most urgent need seems to exist for more accurate estimates of land use emissions.
Another possible approach is to add more data through the combination of many detailed regional studies such as the ones by Schuster and Watson (2007) and Le Quéré et al. (2007), or using process based models combined with data assimilation approaches (Rayner et al., 2005). If process models are used, however, they need to be carefully constructed in order to answer the question of why the AF has remained constant and not shown more pronounced decadal-scale fluctuations or a stronger secular trend.
Michaels adds:
In other words, like we have repeated over and over, if the models can’t replicate the past (for the right reasons), they can’t be relied on for producing accurate future projections. And as things now stand, the earth is responding to anthropogenic CO2 emissions in a different (and perhaps better) manner than we thought that it would.
Yet here we are, on the brink of economy crippling legislation to tackle a problem we don’t fully understand and the science is most certainly not settled on.
UPDATE: A professional email list I’m on is circulating the paper, read it here: Knorr 2009_CO2_sequestration
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Savethesharks –
Interesting circular reasoning. Your response to “how do you empirically test AGW” is “show empirical evidence.” Your response to “what would prove global warming” is “proof.”
My point is simple: It is definitionally impossible to empirically prove a future event. Empirical proof means a real-world result that confirms a hypothesis. So in the case of AGW, the basic hypothesis is that continuing to put CO2 into the atmosphere will cause several degrees of warming. Empirical proof of the AGW hypothesis would mean waiting 50-100 years and seeing how much the temperature has increased. Of course, by that time, it would be too late to do anything about it. So the best we can do is make predictions using models based on our best understanding of how the world works. (Although I’m shortchanging the evidence we DO have: here is an unanswerable proof:
http://www.skepticalscience.com/empirical-evidence-for-global-warming.htm)
Of course, as I’ve said before, all climate skeptic arguments rely on models too, since any alarmist predictions of “economic doom” is based on economic models. These models are based on human behavior, which is much harder to predict than chemistry and physics. Hell, economic models don’t even account for technological change, which is why past analyses of environmental legislation have always overestimated the costs, according to the socialist magazine BusinessWeek: http://www.businessweek.com/investing/green_business/archives/2009/09/one_potential_b.html
So it’s pretty clear that the economic costs of cap-and-trade are much more uncertain than the science of global warming. But don’t ask me, ask the company with the most to lose from global warming:
http://akwag.blogspot.com/2009/11/dont-believe-in-global-warming-ask.html
WAG (21:34:13) :
So it’s pretty clear that the economic costs of cap-and-trade are much more uncertain than the science of global warming.
These models are based on human behavior, which is much harder to predict than chemistry and physics.
You were saying?
WAG,
PROOF is not difficult. Show a credible link between the recorded rise of CO2 and warming.
Not something modeled, not something based on faulty thermometers with horrid siting. Something CREDIBLE.
See, you’re missing the obvious fact that none of what “your side” has demonstrated is the least bit credible.
That really would convince a lot of “skeptics”, but it will never happen. There is no credible evidence to be shown, it does not exist.
See how easy that is?
WAG: “My point is simple: It is definitionally impossible to empirically prove a future event. Empirical proof means a real-world result that confirms a hypothesis.”
As evidenced in the above quote and otherwise: Circular reasoning is definitely YOUR expertise, my friend, so, I understand why you would want to project it on someone else.
Nice try.
If it is “impossible to empirically prove a future event,”…then why not show forth the evidence of the catastrophic, out-of-control global warming, as ALREADY manifested??
Natural climate variations…including recoveries from the LIA…can not be included into the mix.
Where is your evidence? Hard, scientifically proven evidence based upon real-time observations??
Where is it? Show it? Prove it??
Sorry bud, but the burden of proof is on you….or are you going to avoid the logic here too?
Cue chirping crickets.
Chris
Norfolk, VA, USA
CodeTech: “See, you’re missing the obvious fact that none of what “your side” has demonstrated is the least bit credible That really would convince a lot of “skeptics”, but it will never happen. There is no credible evidence to be shown, it does not exist.”
The gritty, grimy, but in the end, CRYSTAL CLEAR truth of the matter.
Chris
Norfolk, VA, USA
WAG says: Of course, as I’ve said before, all climate skeptic arguments rely on models too, since any alarmist predictions of “economic doom” is based on economic models. These models are based on human behavior, which is much harder to predict than chemistry and physics. Hell, economic models don’t even account for technological change, which is why past analyses of environmental legislation have always overestimated the costs, according to the socialist magazine.”
Huh????
Does not compute. Dude….you are jumping logic mid-sentence.
All climate skeptic arguments rely on models too, since WHA???
What is the question here?
You are off your rocker on this post.
Chris
Norfolk, VA, USA
John Finn (03:30:29) :
The ‘mystery’ , here, is why the oceans and biosphere decide to absorb more CO2 just because more is available.
Because co2 has been at a historically very low level for a long time and the trees can’t get enough of it. The planet has vast capacity to become more verdant, and therefore damper. Win Win.
WAG wrote,
“It is definitionally impossible to empirically prove a future event. Empirical proof means a real-world result that confirms a hypothesis. So in the case of AGW, the basic hypothesis is that continuing to put CO2 into the atmosphere will cause several degrees of warming. Empirical proof of the AGW hypothesis would mean waiting 50-100 years and seeing how much the temperature has increased.”
You are perfectly correct there. We cannot empirically confirm a model’s prediction of an event 100 years in the future until that 100 years has passed. We can, however, test the model which makes that prediction in other ways. We can, for example, see whether predictions the model has made in the past for the present have been confirmed. We can also run the model with the starting parameters for some known past time, and see whether the predictions they make track the empirical record. We can also examine the many assumptions upon which the model relies for generating its predictions, and see whether *they* can be verified empirically.
The GCMs available, upon which the IPCC relies for its predictions, have not done well on such tests. They have not, for example, correctly predicted the climate over the last 20 years. When hindcast, they do not predict the MWP or the LIE, which the empirical evidence appears to confirm. The increased frequency and intensity of unusual weather events predicted by the models has not been confirmed either. The correlation between the atmospheric CO2 trend and the temperature trend over the last 100 years is weak. The effects of warming on cloud formation and distribution, which can greatly affect climate sensitivity to CO2, is admitted by the IPCC to be poorly understood. The various assumptions made concerning IR radiative losses, the role and efficiency of various CO2 sinks, the validity of proxies for past temperatures, and numerous others, are challenged by new work on an almost daily basis.
So we don’t have to wait 100 years to evaluate the models. We can evaluate them on the basis of the empirical evidence we have now, and on their performance to date.
“The Oceans are absorbing more CO2, nobody disputes that,”
This is the nub of the problem; they really should dispute it because it doesn’t matter which numbers you stick into Henry’s law, a warming ocean should be a source of CO2, not a sink. The idea that it is a sink comes merely from simplistic and error-filled IPCC arithmetic:
They calculate the amount we emit (which by the way is about 3% of the biosphere flux) then they add an amount from supposed deforestation (the opposite of physical reality in a greening, warming world) then they subtract a calculated amount for tree absorption. They then compare the result with what is measured in the atmosphere and the remainder, called “the missing sink” is assumed to go into the warming sea. This seaborne fraction is then stuck into more models to calculate – not measure – rising pH levels in the sea. This isn’t science it is just bad arithmetic and worse logic.
The whole numerical exercise is invalidated by the massive error bars and the percentage of man’s input versus natures flux. But besides that, the postulated deforestation is far less than natural reforestation so that figure should subtract, not add. They have consistently underestimated the amount absorbed by vegetation and overestimated the residence time of CO2 which makes the official IPCC numbers used practically meaningless.
If you do the arithmetic properly then you don’t get any “missing sink” at all – which would agree with chemistry and physics, unlike the IPCC conclusions. Yet it’s true – few dispute that the “missing” CO2 goes in the sea. Why? Is it general massive stupidity?
Re the bathtub analogy,
Personally I find such analogies useful, as they it allows certain types of consequential reasoning chains to be created, like this:
If the water pressure at the plug-hole varies in response to water depth, then a new, higher equilibrium level may emerge.
As Henry’s law is to do with the partial pressure of the gas above the liquid, then an increase in atmosperic CO2 ought to result in a new higher equilibrium.
Given that Henry’s law indicates around 1: 50 ratio for the equilibrium between free vs dissolved C02 in water, then a CO2 rise of say 2 ppm/yr should indicate that a 100ppm equivalent has been dissolved in the oceans.
So, we could conjecture the need to have an actual initial CO2 emission into the atmosphere of 102 ppm/yr, if we measure a 2ppm/yr increase.
So, how does this 102 ppm/yr compare with the equivalent yearly Anthropic emissions?
carrot eater (17:30:23) :
Bart, your little model is ill-posed from the first line. You have a first-order term for carbon leaving the atmosphere, and a zero-order term for carbon naturally coming into the atmosphere. Why? There isn’t any physical meaning to any of that.
I’ll use made up numbers, but let me try to explain the basic dynamics:
Say there is only ocean and atmosphere. In any given year, 100 units of CO2 go from ocean to air, and 100 units of CO2 go from air back to ocean. On net, the amount of carbon in either place is unchanged.
Now, man starts putting 4 units/year of CO2 into the air directly. Now, 102 units of CO2 go from air to ocean, and 100 units of CO2 go from ocean to air. The amount of CO2 in both ocean and air go up by 2 units/year each. In the terms of the Knorr paper, AF = 50%. Yes, it’s insanely simplified, but I don’t know how else to overcome this difficulty people are having with the transfers.
Bart, if you want your model to actually be able to predict these transfers, you’ll pretty much end up writing a pretty complicated gridded global model.
This is a good description of the process for those (and there seems to be a lot) who are having difficulty getting their head round the issue.
If I could just make a little amendment we might be able to help clear up another misconception about average CO2 residence time. In his example, Carrot eater states that “the amount of carbon in either place is unchanged” . If we now let the unchanged amount be 500 units then it should be reasonably clear to see that each molecule of CO2 has an average residence time of ~5 years. Many people seem to think that this apparently short time means that CO2 levels will drop very quickly if Anthro-CO2 emissions are reduced. They won’t because the residence time is governed primarily by the absorption and natural emission rates.
Carrot eater is, no doubt, a dyed in the wool warmer ( nobody’s perfect 🙂 ), but it might be worth inviting him or her to do a simple, short post explaining the numbers behind the carbon cycle. There are a lot of percentages being bandied about and most (~93.46%) of them are clearly borne out of confusion.
tallbloke (00:10:09) :
John Finn (03:30:29) :
Because co2 has been at a historically very low level for a long time and the trees can’t get enough of it. The planet has vast capacity to become more verdant, and therefore damper. Win Win.
Then why didn’t the trees absorb ALL the anthropogenic emissions when emissions were lower.
At the end of the day human emissions are responsible for the atmospheric CO2 increases – particularly over the last 50 years. The fact that concentrations are not rising as much as expected just means that the 2 x pre-industrial CO2 level might not be reached until ~2100 rather than ~2060 or whatever.
CodeTech (22:37:00) :
PROOF is not difficult. Show a credible link between the recorded rise of CO2 and warming.
Not something modeled, not something based on faulty thermometers with horrid siting. Something CREDIBLE.
That really would convince a lot of “skeptics”, but it will never happen. There is no credible evidence to be shown, it does not exist.
A truly amazing set of statements
We will not believe AGW without absolute proof.
We know that there is no true record of temperature to present day
You cannot use models
We need provide no proof of GW without the A
Where does that leave humanity.
AGW CANNOT be proven – you have dismissed all evidence.
We must wait to see what happens in 50-100 years.
We will then take action if necessary.
BUT it takes decades to change the climate.
You have postulated that GW is not AGW, but you have no PROOF –
you have no proof of cycles (the temperature record is faulty).
You cannot prove LIA/MWP/RWP etc as this relies on hearsay and temperature records.
You do not know the effect on ALL of ecology of increased CO2.
Unless proof that GW is not AGW, or AGW is true, or there is no GW, we are setting sail on a course with unknown destination.
Is this wise with the world at stake?
Which is the safe option? Is wealth more important than humanity?
Your statements say AGW cannot be proven. So surely it should be up to the sceptics to provide proof that AGW is not happening? Isn’t there too much at stake to tell warmists you must prove AGW whilst saying that this is impossible and we will not believe it anyway?
hmmm, interesting!
JamesG (01:47:08) :
http://img527.imageshack.us/img527/6153/co2manysitesch4.jpg
Take the 1st cycle shown for Barrow:
Min=358.5ppm
Max=375.5ppm
difference = 17ppm
This is similar over the whole record (I have not mathematically checked this)
This represents the absorption of CO2 by flora and fawna.
It does not seem to be linked to sea temperature
At the current growth rate:
http://img687.imageshack.us/img687/8276/growthrateco2year.jpg
this is equivalent to about 9 years of increase.
Since this breathing of CO2 has remained at at similar amplitude over the data record (i’ll check this later) There does not seem to have been an increase in flora/fauna absoption unless this is happening in the tropics (no seasons).
Why is the greening of the near-arctic not absorbing more CO2?
Bart (16:15:14) :
I have a much simpler model, which covers at least the previous 800,000 years (from ice cores) up to the most recent data:
C(new) = C(old) + 0.55*d(emissions) +4*dT
Where the short term dT factor of 4 ppmv/K must be increased to 8 ppmv/K for (very) long time periods. The factor 0.55 for the emissions is a matter of physics: at one side we have the “baseline” CO2 levels, dictated by the temperature level and a disturbance by adding some extra CO2 to the dynamic equilibrium. The disturbance is removed at a rate of about 38 years (half life time) or 55 years (e-folding time), see the work of Peter Dietze, who has figured it out:
http://www.john-daly.com/carbon.htm
With a constant addition of about 7 GtC/year, a new equilibrium would be reached at about 420 ppmv (+130 ppmv over the 290 ppmv equilibrium at current temperatures). But as we emit with increasing amounts, there is little hint of a new equilibrium and CO2 goes up near linearly.
Bart,
Here is the first line of your model.
Cdot = -C/tau + u + delta_u
Just looking at it, one can see already that it will give unphysical results, mainly due to the first term. I’m trying to spare you the trouble of trying to then understand those unphysical results.
The u term is what you’re calling the natural inflow term. You would have this include exchanges from the oceans, soils, vegetation, volcanoes, and whatever else. Because you don’t want to actually write a huge model that physically describes all those things, you’ll cheat and say you already know it’s roughly constant over time, so you put it in as a constant. OK, fine for now, though it will limit the usefulness of the exercise. For one, the natural flows will change slightly as man adds more carbon to the picture, but let’s neglect that for now.
Then you have a delta_u term for man-made contributions. You say it increases linearly over time; as a first approximation, fine. But if that’s what you want it to do, you should do what you say and actually write it as a term that’s linear with time:
man term = (some slope)*t.
I see you wanted to say this term was roughly equal to 0.03 * u, which might be roughly true for now, but if you actually solve your differential equation, you’ll end up with a constant man-made inflow, not one that’s linear with time.
But my biggest problem is with your -C/tau term: this, presumably, is to describe exchanges back to the oceans, soil, vegetation, rocks, and whatever else. If you were being consistent, you should have just made this a constant, just like your natural inflow term u. Instead, you tried to half-way describe the physics of the transfer in there, by saying the outflow was proportional to C, and ended up with something unphysical.
If you still don’t see the issue, then consider your model in the absence of man:
dC/dt = -C/tau + u
You can see that in the absence of man, the amount of carbon in your atmosphere changes over time. That alone should tell you there’s a problem.
For the fun of it, that solves to
C = (Co – u*tau)(exp(-t/tau)) + u*tau. C starts at Co, and then exponentially decays to u*tau. This decay has no physical meaning; it’s just an artifact of how you set up the model, with a constant natural inflow and a non-constant natural outflow.
bill (03:39:23) :
“Why is the greening of the near-arctic not absorbing more CO2?”
Because of the lower temperatures lead slow growth.
JamesG:
“it doesn’t matter which numbers you stick into Henry’s law, a warming ocean should be a source of CO2, not a sink. ”
There are all sorts of issues with this statement. Mainly, you’re ignoring that the partial pressure of CO2 in the air above is increasing at the same time. You’re also treating the ocean as one well-mixed fully saturated body, and then we’ve got the multiple chemical equilibria in the ocean, and biological interactions. You’ll see it isn’t easy to predict a priori whether the oceans will be a net source or sink. You should think things through before you accuse an entire field of being unable to do chemistry or physics.
Ferdinand Engelbeen:
In your little model, you have a term “+4*dT”, where dT looks like the change in temperature. I’m guessing you invoked that term to cover the change in atmospheric CO2 levels coming in and out of the ice ages. That’s fine; it’s a statistically fit term, but fine (I’m not at all fine with the non-constant constant, 4 or 8, but that’s for another day). Your 0.55 I’m guessing corresponds to Knorr’s 0.46, the airborne fraction? I’ll assume you’ve taken care of unit conversions as needed.
My question: do you keep that thermal term during the interglacial, meaning, now? You shouldn’t, because that term is for a process that isn’t currently occurring. The thermal term is saying that the land and ocean are net sources, not sinks. But from your comments, I can tell you accept that the ocean is still a sink. So this is an inconsistency.
John Finn (02:44:37) :
tallbloke (00:10:09) :
co2 has been at a historically very low level for a long time and the trees can’t get enough of it. The planet has vast capacity to become more verdant, and therefore damper. Win Win.
Then why didn’t the trees absorb ALL the anthropogenic emissions when emissions were lower.
Because it takes time for trees to get fatter and generate bigger appetites.
http://www.telegraph.co.uk/earth/environment/climatechange/5109251/Trees-are-growing-faster-and-could-buy-time-to-halt-global-warming.html
At the end of the day human emissions are responsible for the atmospheric CO2 increases – particularly over the last 50 years.
Only if you assume all else is equal. Which it clearly is not.
Looking at the Mauna Loa graphs, I have doubt over accepting that a signal of apparent annual fluctuation of atmospheric CO2 is due to vegetation behaviour in the northern hemisphere.
I can understand that greenery eaily takes up CO2 in the growing season, but I can’t see how the greenery then gives up C02 just as easily, in the autum and winter.
Maybe the fluctuations are partly due to our old friend Henry’s law and the arctic ocean. IF ice does not take up CO2, but the cold sea-surface does, then we could see a huge difference in CO2 absorbtion as the artic ocean thaws and ices over.
WAG: ” Empirical proof of the AGW hypothesis would mean waiting 50-100 years and seeing how much the temperature has increased. Of course, by that time, it would be too late to do anything about it.”
I find this remark typical of AGW alarmists. It’s as if we’ve reached our technological pinnacle and nothing will be learned in the next 100 years. Obviously, this demonstrates less than optimum critical thinking abilities. The truth is we should be able to handle the problems far more easily in 100 years than we can today if we need to. WAG, if you don’t understand this look at technology 100 years in the past.
The real issue here is this typical of most AGW supporters. Are they really this limited in their abilities to think ahead?
“Climate change study shows Earth is still absorbing carbon dioxide”
http://www.telegraph.co.uk/earth/earthnews/6538300/Climate-change-study-shows-Earth-is-still-absorbing-carbon-dioxide.html
It’s in the Telegraph
Here’s a relevant example to my previous post.
What if man had found a rather large asteroid in space early in the 20th century. Using the technology of the time we could predict that the asteroid would impact the Earth in 100 years. The impact would occur in the middle of the North Atlantic creating massive tsunamis that would flood all coastal areas less than 100 feet in elevation.
One approach to this problem would have been to evacuate all coastal areas and use them for specific purposes but no one could live there. This would have been extremely costly to society at the time. We could also have undertaken building massive sea walls along all the coastal regions. Do these approaches sound a little bit like many of the AGW solutions where we MUST act now? Of course, we now know we could have sent space craft developed 40-50 years later and redirected the asteroid at minor costs to society. Not only that but the calculations at that time may have been off by just enough so that the asteroid would have missed Earth altogether and advances in technology could have determined that in due time. Many times a wait and see attitude is far superior to knee-jerk reactions based on limited knowledge.
This example demonstrates that acting now on imprecise knowledge is probably not a good idea for something that won’t be a problem for many decades. The “it will be too late” argument is really very poor.