Guest Post by David Middleton
Fingerprints are admissible evidence in criminal trials because of their uniqueness. The probability of two human beings having identical fingerprints is very low.
Measurements of δ13C depletion have often been cited as anthropogenic “fingerprints,” proving human culpability for the rise in atmospheric CO2 over the last 200 years or so…
While δ13C depletion certainly could be evidence of the Suess Effect, it is not a unique solution; therefore, not a “fingerprint.”
Examples of geologically recent δ13C depletion not of anthropogenic origin…
δ13C depletions were associated with warming events ~5,000 years ago in India, ~9,100 years ago in Poland and ~150,000 years ago in the Indian Ocean. It appears to me that δ13C depletion has been a fairly common occurrence during periods of “global warming.” It also appears that δ13C increases have occurred during periods of global cooling…
The red curve in Figure 5 is the Flinders Reef δ13C that was cited as “Human Fingerprint #1” in Skeptical Science’s The Scientific Guide to Global Warming Skepticism. The rate of δ13C depletion is quite similar to that of the lacustrine deposit on the Yucatan. The Flinders Reef data do not extend back before the Little Ice Age; so there is no way to tell if the modern depletion is an anomaly, if the δ13C was anomalously elevated during the 18th and 19th centuries and the depletion is simply a return to the norm or if δ13C is cyclical.
Is it possible that Skeptical Science’s “Human Fingerprint #1” is not due to the Suess Effect? Could it be related to the warm-up from the Little Ice Age?
References
Cook, J. et al., 2010. The Scientific Guide to Global Warming Skepticism. Skeptical Science.
Banakar V., 2005. δ13C Depleted Oceans Before the Termination 2: More Nutrient-Rich Deep-Water Formation or Light-Carbon Transfer? Indian Journal of Marine Sciences. Vol. 34(3). September 2005. pp. 249-258.
Enzel, Y. et al. High-Resolution Holocene Environmental Changes in the Thar Desert, Northwestern India. Science 284, 125 (1999); DOI: 10.1126/science.284.5411.125.
Apolinarska, K. δ18O and δ13C Isotope Investigation of the Late Glacial and Early Holocene Biogenic Carbonates from the Lake Lednica Sediments, Western Poland. Acta Geologica Polonica, Vol. 59 (2009), No. 1, pp. 111–121.
Hodell, D.A., et al., 2005. Climate change on the Yucatan Peninsula during the Little Ice Age. Quaternary Research, Vol. 63, pp. 109-121. doi:10.1016/j.yqres.2004.11.004
Pelejero, C., et al. 2005. Flinders Reef Coral Boron Isotope Data and pH Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2005-069. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
AFAICS the fundamental difference between Bart (B) and Ferdinand/Gavin (FG) is that FG assume natural carbon sources N remain constant, whereas Bart assumes N varies.
FG: dM/dt = A + N – kM
B: dM/dt = c(A+N) – kM with approximations C=1/2
So before 1750 (A=0, M=M0)
FG) N=k*M0 –> k=N/M0
B) N/2=k*M0 –> k=N/(2M0)
now:
FG) kM = A/2 + N (k depends on A for constant N)
B) kM = N/2 ( k depends on N)
For FG the net increase in CO2 is only due to A and sinks increase linearly with net partial pressure.
For B the net increase in CO2 is due to A – PLUS an increase in N . The sink increases ONLY in response to the natural increase in N, because (he argues) they are coupled together.
What I learned was:
– There is always an equilibrium value for CO2 concentrations in any period on Earth. When volcanic activity was much higher a major source of CO2 was from the Earth’s crust and equilibrium levels were > 1000 ppm. Currently volcanic sources are about 1% of anthropogenic sources – although that could increase at any time. Without human emissions the equilibrium content of CO2 in the atmosphere would be ~ 290 ppm.
– The Net e-folding time for CO2 is ~52.5 years. This means that if humans stabilize emissions at roughly current values of 8Gt per year, and continue to emit 8 Gt/year forever then….
the final CO2 content of the atmosphere will be 500 ppm. Is this so terrible ?
Fitting the observed temperature rises to SB response to CO2 forcing gives DT = 2.5 Ln(C/C0) and a final temperature rise of 1.5 deg.C ! The climate could turn out to be actually better for mankind and the natural world !
Another ice is a far more serious threat !
Perhaps there is some confusion because I did not define the following terms clearly (amended here):
A = anthropogenic input flux
N = natural input flux
These are the time derivatives of concentration, not the concentration itself. M is the time integral of terms in A, N, and M itself.
The “k” term is a constant. It does not change. It quantifies the expansion of the sinks as M increases, i.e., it is a sensitivity term. In the real world, it may vary somewhat, but you should assume it is constant.
Ferdinand, your fundamental argument is that M := 1/2 * integral(A). Keep that in mind when looking at the conclusions you are driven to with your math. E.g.,
N = kM – (1-b)*A
means
M = (N + (1-b)*A)/k
A is on the order of something like a couple of ppmv/year equivalent/ If “k” is “large”, then it cannot possibly account for the measured concentration. That is the point I have been driving at all along.
IF “k” is “small”, then the equation works out to approximately
M = c*integral(A + N)
with c = 1/2 and N = 0, this gives the solution you want. But, it is not the only solution which is allowed by the observations.That is the point I have been driving at all along.
Bart says:
April 4, 2012 at 9:27 am
“Pitiful. Absolutely pitiful.”
My apologies for intemperate remarks. My anger is not at your making mistakes – I am very patient with my students when they are trying to learn, and making mistakes is a very good way to learn.
My anger is that you guys seem not to know even half of the actual arguments which have gone into the present state of the science over a span of decades, and yet you have set yourself up as authorities to proclaim how “skeptics can retain credibility”.
That really is unforgivable hubris.
Bart writes “From that point of view, a crystal radio receiver could never work, because every rectified half wave would have the same area.”
You have missed Ferdinand’s point. As you have used an analogy, so will I. If I have jar containing 30 sweets, and every day I take 20 sweets out and eat them, but also buy a packet of 20 sweets and put them in the jar, then there has been a turnover of 20 sweets, but it hasn’t affected the number of sweets in the jar at the end of the day.
Likewise the oceans emit about 90GtC/year of carbon into the atmosphere each year (IIRC) but take in about 92GtC/year. So the oceans cause a turnover of about 90GtC/year, which has no effect on the amount of CO2 in the atmosphere, and a net flux of about 2GtC/year, which means the oceans also take about 2GtC/year out of the atmospheric reservoir.
You can disagree with the figures if you like, however Ferdinand’s point about an exchange flux not affecting atmospheric CO2 levels stands.
Also you may think think your model obeys mass balance, you have not gone through the mass balance argument step by step. For a very good reason, which is that you know that if you did go through it step by step you would not be able to identify a flaw, hence your unwillingness to give direct answers to direct questions.
clivebest wrote: “AFAICS the fundamental difference between Bart (B) and Ferdinand/Gavin (FG) is that FG assume natural carbon sources N remain constant, whereas Bart assumes N varies.”
This is not correct, as I have stated several times the mass balance argument makes no assumption that anything is constant. The model of Essenhigh that I adapted to show the difference between residence time and adjustment time does, however it is the mass balance argument that demonstrates that the rise is anthropogenic. The one box model just shows that the observations are consistent with a simple model of the carbon cycle based on mainstream science.
clivebest wrote “The Net e-folding time for CO2 is ~52.5 years. This means that if humans stabilize emissions at roughly current values of 8Gt per year, and continue to emit 8 Gt/year forever then….the final CO2 content of the atmosphere will be 500 ppm. Is this so terrible ?”
This is not correct. It is the difference in partial pressure between the atmosphere and surface ocean that drives the oceanic sink. If the atmospheric concentration stabilises, then as the surface ocean takes up more CO2, the partial pressure difference falls as they come back into equilibrium and the sink would shrink. While we keep anthropogenic emission at current rates the atmospheric concentration will continue to rise. If the sinks can’t deal with our emissions now, why should they be able to cope with the same levels in the future when they are heading towards saturation (thankfully they are not there yet)?
Gavin,
That simply can’t be right. The earth maintained CO2 levels of over 1000 ppmv for millions of years during the dinosaur era, presumably because volcanic sources of CO2 were many times greater than today’s anthropogenic sources. The atmosphere stabilized then as it will do in the future if man can remove the second derivative ( an increase of the increase).
Every year man adds a pulse of N0= 8 Gt of CO2. This then decays away with a lifetime Tau. The accumulation of fossil CO2 in the atmosphere for year n is simply given by.
CO2( n) = N0( 1 +sum(i=1,n-1) (exp(-n/Tau)))
If we assume that n is very large then we can treat this sum as an infinite series and the atmosphere will eventually saturate at a certain value of anthropogenic CO2 concentration.
Multiplying both sides by exp(1/Tau) we can derive that the sum in the limit as n-> infinity :
CO2(n) = N0/(1-1/exp(1/Tau))
For tau = 53 years we get CO2(infinity) = 1.7*(pre-industrial values) or about 500 ppmv.
The Mauna Loa data is rising approximately linearly because we are accelerating emissions. All we have to do is stabilize them at some reasonable value. Even if we just burned all fossil fuels it would still eventually stabilize. The danger facing western civilization right now is economic suicide through climate change hysteria.
clivebest says:
April 4, 2012 at 9:53 am
“For B the net increase in CO2 is due to A – PLUS an increase in N . The sink increases ONLY in response to the natural increase in N, because (he argues) they are coupled together.”
No, I am not arguing that at all. The sinks do not discriminate. But, if the sinks are strongly activated, they will bleed out the anthropogenic component before it can build up. Therefore, in that case, the natural input has to be the driver. Since the natural component cannot be quantified by current knowledge, there is no limit on how large it can be, so there is no way to eliminate the possibility.
gavincawley says:
April 4, 2012 at 10:59 am
“You have missed Ferdinand’s point.”
If I have a bucket into which I am alternately pouring in a liter of water, then emptying it out, then my average volume of water is 1/2 liter. If I now alternatingly put in 2 liters and empty it out, my average volume is 1 liter. The exchange volume matters.
“Likewise the oceans emit about 90GtC/year of carbon into the atmosphere each year (IIRC) but take in about 92GtC/year.”
You do not KNOW this. These are estimates which are calculated under the constraint that your model for the entire system is correct. You have to impose such constraints to get an answer, because you have too many unknowns for the equations. But, it is circular logic. It proves nothing.
“…if you did go through it step by step you would not be able to identify a flaw…”
I have already identified the flaw. I have repeated it over and over and over. It just sails right over your head. The flaw is this: you are assuming that the atmosphere acts as a pure accumulator (no ultimate sinks) and that the natural balance is perfectly steady. There is no evidence available which confirms either of these assumptions.
Look, this is very simple. The response to both N and A is precisely the same. If the constant “k” is large (sinks are very active), then the atmospheric concentration will closely track (c/k)*(N+A). In this case, A is not large enough to account for the measured concentration, so N has to be the driver. In the case where “k” is small, the concentration will track c*integral(N+A). If “c” is close to 1/2, then the accumulation has to be driven by A. If “c” is substantially less than 1/2, then N is playing a significant role, too.
clivebest says:
April 4, 2012 at 9:53 am
AFAICS the fundamental difference between Bart (B) and Ferdinand/Gavin (FG) is that FG assume natural carbon sources N remain constant, whereas Bart assumes N varies.
Not at all, the only assumption in the mass balance equation that F, G & I use is the that the rate of change of atmospheric CO2 is given by the sum of Anthropogenic flux (A) and all other source fluxes (N) minus the sum of all sink fluxes (S):
d[CO2]/dt = A + N – S
These variables are free to vary as much as they like, and they have varied over time, however d[CO2]/dt≈A/2 over the last 50 years, therefore (N-S) has consistently been negative (i.e. a net sink). This is a proper mass balance, despite being asked Bart has avoided saying what’s wrong with this equation, other than to say it’s not complicated enough, which he solves by removing half of the source flux and making the sink terms a linear function of CO2! Bart is trying to produce a much more complicated model involving magically losing about half of the source flux, introducing variables he never defines and admittedly uses incorrect values for others, which doesn’t answer the question being asked anyway.
Regarding his constant ‘k’, it is variously:
The “k” term is a constant. It does not change. It quantifies the expansion of the sinks as M increases, i.e., it is a sensitivity term……
If “k” is “large”, then it cannot possibly account for the measured concentration. That is the point I have been driving at all along.
IF “k” is “small”, then the equation works out to approximately
M = c*integral(A + N)
with c = 1/2 and N = 0, this gives the solution you want….
But we are also told:
the term involving “k” represents ultimate sequestration in the ocean…
Under the assumption that “a” is much greater than “k”,
………
Which is to say that the differential equation is approximately
Mdot := 0.5*(N + A) – k*M
So are these different variables or not? According to the latter definition k*M goes into the ocean permanently and 0.5(N + A) goes into the ocean temporarily but never comes back out!
Bart, take a deep breath and sort it out because this is a real mish-mash.
And preferably stop generally insulting and abusing anyone who doesn’t agree with you!
“Pitiful. Absolutely pitiful”, “WHICH IS WHAT I EFFING SAID SEVERAL POSTS AGO!!!!! But, apparently, I have to spoonfeed it to these youngsters”, “The “mass balance argument” is, there is no way to sugarcoat this, stupid”, “Again, sorry, it has to be said… Stupid”
Bart wrote: “If I have a bucket into which I am alternately pouring in a liter of water, then emptying it out, then my average volume of water is 1/2 liter. If I now alternatingly put in 2 liters and empty it out, my average volume is 1 liter. The exchange volume matters.”
That is an inappropriate example. The average volume of water in the bucket is only 1/2 becase you are putting one liter in as a discrete action and then taking one liter out as a discrete action. However the carbon cycle is continuous, not discrete. If you put one liter in and took one liter out, but by alternating putting one tea spoonfull in and one spoonful out then the average amount of water in the bucket would be half a teaspoon full, but the volume of the exchange would be the same. At the end of the exercise the level of water in the bucket would be exactly the same as it was at the start. This is because an exchange doesn’t affect the volume of the reservoir. To do that you need a difference between the amount in and amount out, and it is this difference that matters, not the volume.
“I have already identified the flaw. I have repeated it over and over and over.”
No you have not identified a flaw as you refused to go through the step by step analysis and instead went off at a tangent based on an issue that is not actually part of the mass balance argument. If you really want to prove me wrong, then the easiest way is to go through the six steps one by one, saying where you agree and where you dont. By continually avoiding this you are just demonstrating that you know as well as everybody else that you will not be able to identify the flaw.
clivebest David Archer has written a primer on the carbon cycle that explains in great detail how the carbon cycle will respond, it is a lot more complex than the very simple models being discussed on this thread (which is why I gave the caveat in my paper that such simple models are of little use for quantative rather tha qualatative analyses, and gave some details of the shortcomings of such models). It is well worth a read.
However, I have already pointed out the flaw in your argument, which is that as the oceans take up carbon the partial pressure difference between oceans and atmosphere will be reduced and so will the flux of carbon into the oceans. Thus CO2 concentrations cannot stabilise unless we reduce anthropogenic emissions to the point where they match the capacity of the natural sinks. However the growth of the natural sinks is a result of increasing CO2, so if levels stabilise they will no longer expand, but will instead shrink.
gavincawley says:
April 4, 2012 at 12:32 pm
“The average volume of water in the bucket is only 1/2 becase you are putting one liter in as a discrete action and then taking one liter out as a discrete action. However the carbon cycle is continuous, not discrete.”
We were speaking specifically of vegetation, and eras of growth and decay.
But, you do bring up a point about why I made the crystal radio receiver analogy. The continuous action of varying rates of growth and decay across the entire spectrum of vegetation would tend to low pass filter the cycling, and the average difference becomes a steady difference. Just like in a crystal radio, where the signal is rectified, then smoothed through a low pass filter. The average of the rectified signal is then what comes out of your speaker.
A final way to look at it: take the reductio. Are you telling me there would be no difference in CO2 concentration if the Earth were a dead planet, with no vegetation at all, compared to what it is now?
“If you put one liter in and took one liter out, but by alternating putting one tea spoonfull in and one spoonful out then the average amount of water in the bucket would be half a teaspoon full, but the volume of the exchange would be the same.”
Take a breath. Try again. Think it through.
“If you really want to prove me wrong…”
I have already proven you wrong. I have laid it out for you on a silver platter with bone china and crystal goblets. If you do not understand now, I do not see much hope that you ever will.
Bart says:
April 4, 2012 at 10:03 am
M := 1/2 * integral(A)
That M is about halve the integral of A over time is what is observed, but nobody insists that it must be that (not even the IPCC), M may be negative or zero or higher than integral(A) over time, as the real M := integral(A) + integral(N) – integral(kM)
where M = difference with the historical Mo for the current temperature.
and k = ~210/4 = ~52.5 (the current M / observed sink rate).
and integral(kM) > integral(N) at least over the past 50+ years, including kM > N in every individual year (a nice but not necessary condition).
That means that integral(N) is simple throughput – turnover through the atmosphere, where the difference between integral(kM) and integral(N) is the observed sink capacity of nature as a whole, whatever the height of integral(N) or its variation. The only constraint is that the measured increase over the full period is less than integral(A), even if in one or more years N > kM.
The equation M = c*integral(A + N) has no single solution, because both c and N are undefined, while the above equations have a single solution for the increase in the atmosphere as result of integral(A) and the known difference between integral(N) and integral(kM), whatever these two terms individually may be. If k didn’t change too much over time, it is even possible to calculate integral(N), which probably is near zero (as it was in pre-industrial times).
BTW, the CO2 storage in reservoirs and the fluxes between them can be compared to a capacitor in a radio circuit. Your radiowave passes the capacitor without problems, but doesn’t leave any change in storage on the capacitor at the end of any full wave…
Bart wrote “I have already proven you wrong. I have laid it out for you on a silver platter with bone china and crystal goblets.”
no, you have attacked the straw man of an argument I did not make, not the mass balance argument. You can tell this by the fact that we only got as far as step #1 in the argument I am actually making.
“If you do not understand now, I do not see much hope that you ever will.”
Well perhaps going through my argument step by step and point out my error when I make it. That will make it much easier for me to understand where I am going wrong. Unfortunately you seem to be extremly unwilling to do the one simple thing that would resolve the issue very quickly,
Perhaps in the short term. However, in the longer term an equilibrium must be attained so long as fluxes remain sufficiently stable over many decay lifetimes – and CO2 becomes distributed throughout the ocean depths leading to long term sequestration. Otherwise how the hell did life and liquid oceans survive for the last 3 billion years ? I have the feeling that this is an argument that cannot be resolved by resorting to more complex models.
Clivebest wrote “However, in the longer term an equilibrium must be attained so long as fluxes remain sufficiently stable over many decay lifetimes”
However I have pointed out that the fluxes will not remain stable as the net oceanic sink will dissapear as the partial pressure of the surface waters equilibriates with the atmosphere. At that point the adjustment time will grow as the uptake into the thermocline is no longer the bottleneck.
I have the feeling that this is an argument that cannot be resolved by resorting to more complex models”
Yes, exactly, such as CEOCARB or the type of model that Archer describes in his primer (and research articles). As I said, such simple models as those discussed on this thread are only really useful for qualitative analysis of the most basic behaviour of the carbon cycle and we need to bear their limitations in mind.
The mass balance argument however is not a model, and it is useful for quantative analysis of the observations.
gavincawley says:
April 4, 2012 at 12:45 pm
“…it is a lot more complex than the very simple models being discussed on this thread…”
Under very general conditions, the system can always be linearized such that the atmospheric concentration is governed by an equation of the form
dM/dt := c*(N+A) – k*M
Please note that all of the terms in the above equation are anomalies from the state at which the linearization was performed. This equation will hold approximately within a local neighborhood of the current state and time.
“However, I have already pointed out the flaw in your argument, which is that as the oceans take up carbon the partial pressure difference between oceans and atmosphere will be reduced and so will the flux of carbon into the oceans.”
Again, the flaw in your argument here is that you are assuming that there are no significant permanent (or, “semi-permanent”) ocean sinks. There are many, and more are being discovered every day.
“Thus CO2 concentrations cannot stabilise unless we reduce anthropogenic emissions to the point where they match the capacity of the natural sinks.”
The sinks do not have any known capacity limit. Dissolution in the ocean is not really a “sink”, per se, as it does not remove the carbon from the system on either a permanent or long-term basis.
“However the growth of the natural sinks is a result of increasing CO2, so if levels stabilise they will no longer expand, but will instead shrink.”
No, the increased uptake of the sinks is a result of increasing CO2. If anthropogenic input stabilizes, then the portion of the rise attributable to them will stabilize. That portion may be roughly 50%, or it may be very small. We simply do not have enough information beyond our personal biases to determine it.
gavincawley says:
April 4, 2012 at 1:17 pm
I’m not going through your playschool argument with you.
Further to what Ferdinand has just said, the one box model of the carbon cyle used in my paper produces a constant airborne fraction of IIRC about 0.58 as a consequence of exponential growth in anthropogenic emissions (which is a reasonable approximation to what we have actually seen); it isn’t an assumption that is built into the model. The reason that it is 0.58 rather than 0.45 is that the model is based on a differential equation that is only a first order local approximation of reality at best, but produces results in good qualatative agreement with reality.
FerdiEgb says:
April 4, 2012 at 1:17 pm
“… as the real M := integral(A) + integral(N) – integral(kM)…”
That is really infuriating. It shows complete lack of understanding, and willful insistence on plowing ahead with your own otherworldly reality regardless. I’m not going to dignify your post with any further comment.
gavincawley says:
April 4, 2012 at 12:45 pm
David Archer has written a primer on the carbon cycle that explains in great detail how the carbon cycle will respond, it is a lot more complex than the very simple models being discussed on this thread
This is the only point where I differ with you in your essay. Archer sees different constraints, some true, some questionable. The constraint in uptake for the ocean surface is certainly true for the Revelle factor, as can be seen in the increase of DIC (dissolved inorganic carbon) which is only 10% of the increase of CO2 in the atmosphere. Thus even if the equilibrium between the atmosphere and the ocean’s mixed layer is very fast (order of ~1.5 years), that reservoir can only take in 10% of the increase. The deep ocean exchange is quite different: the main intake is in the polar waters, mainly in the NE Atlantic where the CO2 partial pressure difference pCO2(atm) – pCO2(aq) is about 250 microatm (400-150 microatm), as the waters there are extremely cold. This pressure difference pushes a lot more CO2 directly in the deep oceans, which are at some 5 degr.C. The deep ocean waters contain some 37,000 GtC as DIC, but are far from saturated. Thus any extra CO2 coming in via the THC will simply mix up with the rest of the carbon mass, depending how readily that mixes and comes up some 800-1000 years later into the warm equatorial Pacific. There a lot of CO2 is released, due to the high temperature.
Archer now uses the same 10% rule for the deep oceans as for the ocean surface, but that isn’t true, as the deep oceans still are far from saturated and any considerations of the Revelle factor only holds for the air-ocean surface interchange (which at polar waters only increases), not for deep ocean waters. Thus if we assume that the ~370 GtC that humans have emitted ultimately all end in the deep oceans, that would increase the deep oceans carbon content with ~1%. At the ultimate steady state with the atmosphere, that would also give a 1% rise in the atmosphere above the pre-industrial CO2 level, or 3 ppmv.
The reasoning also holds a fortiory for the biosphere: there is no limit in the storage capacity of the biosphere, as the millions of years old gigantic coal beds show. This too is a relative fast and increasing (semi) permanent storage. Thus there is no reason to think that some 30% of the increase in the atmosphere remains there near forever…
Bart wrote “I’m not going through your playschool argument with you.”
Going through an argument step-by-step is not a playground argument, it is how science actually operates. The reason for going through the argument step by step is that it means you cannot substitute a straw man argument in place of the argument I am actualy making. The reason you will not engage in that exercise is that you know tha on that basis you will fail to identify an error and will be proven wrong.
Ferdinand, I would agree that things get more difficult as you get into the more advanced issue and things become more uncertain and I am comfortable with there being disagreement. My primary interest is to try and put an end to the argument that the rise in atmospheric CO2 is natural; this sort of argument is enormously damaging to the “skeptic camp” and does neither side of the discussion any good. It would be nice if the advanced issues could be discussed once the very basics are more widely accepted.
Phil. says:
April 4, 2012 at 12:22 pm
“k” can be “small” with respect to “a” without being “small” with respect to evolution of the system within time intervals of interest.
I made the variable “c” and said it could be near 1/2, because 1/2 is the line of those who attribute the rise to humankind. I agree completely that it is probably much less, and that would KO the anthropogenic attribution argument.
For the rest… just read more carefully.
“And preferably stop generally insulting and abusing anyone who doesn’t agree with you!”
I’ve been holding back. It isn’t the disagreement, particularly, that I find annoying. It is disagreement for reasons which aren’t even remotely valid by people who have set themselves up as experts.
gavincawley says:
April 4, 2012 at 2:01 pm
“The reason you will not engage in that exercise is that you know tha on that basis you will fail to identify an error and will be proven wrong.”
No. It is because I know the error in your reasoning, and going through it with you will do me no good. You are trivially wrong.
It will not do you any good, either, because you appear not to know when you are making implicit assumptions and, when I point them out to you, you deny them.
This system is trivially Controllable through N. It is elementary that you can therefore always find a natural forcing which will produce the output you want. The size of N (or, rather, the deviation from historical norms) needed is what counts. If it is “small” compared to A, then it is not significantly driving the rise. If it is large, however, then it is. How large or small it will be depends completely on the parameters, which I have reduced to “c” and “k” in the model I have profferred. If the sinks are active, then the rise is not most significantly anthropogenically driven. If the diffusion of CO2 into the oceans is not approximately 1/2 of the net atmospheric transfer, then the rise is not most significantly anthropogenically driven. If the sinks are weakly active and the diffusion is about equal, then the rise is anthropogenic.
Those are the twin pillars upon which anthropogenic attribution is founded: weak sinks, and even atmospheric/ocean distribution. That edifice was not constructed by me on that foundation, but by the authors of papers stretching back decades who recognized the requirements for anthropogenic attribution. There is a mound of modeling assumptions which have gone into that construct, from buffering action of the oceans to discounting of unknown processes. It is a shaky foundation. Whether it stands far into the future, we will just have to wait to see.
“My primary interest is to try and put an end to the argument that the rise in atmospheric CO2 is natural; this sort of argument is enormously damaging to the “skeptic camp” and does neither side of the discussion any good.”
I have not been arguing that it is natural. I have been saying that there is not enough information to clinch the argument. Given popular perceptions, maybe it harms the skeptic camp. Than again, maybe it doesn’t. Since it isn’t a front burner issue right now, given the very obvious shortcomings in the rest of the AGW conjecture after a decade of stagnation in the temperature metric, I doubt it is hurting anything right now.
I am much more put off by those who deny the basic greenhouse physics through misguided appeals to the 2nd law or whatever. But, again, the basic stagnation and incipient downturn in temperatures will carry the day, and I am not overly concerned about it.
Bart wote “No. It is because I know the error in your reasoning, and going through it with you will do me no good. You are trivially wrong.”
Sorry, I am happy to have a civil discussion of the science, but you have made it abundantly clear that you will not engage with the actual argument, just the straw man of your own devising and can’t conduct a discussion in a reasonable polite manner. There is little point in continuing, but I will just point out again that this is exactly the sort of behaviour that Prof. Singer says gives the skeptics a bad name (it is one of the obviously incorrect arguments that he mentions in his article).