This interesting essay by Dr. Spencer is reposted from his blog, link here:
Global Warming Causing Carbon Dioxide Increases: A Simple Model
May 11th, 2009 by Roy W. Spencer, Ph. D.
Global warming theory assumes that the increasing carbon dioxide concentration in the atmosphere comes entirely from anthropogenic sources, and it is that CO2 increase which is causing global warming.
But it is indisputable that the amount of extra CO2 showing up at the monitoring station at Mauna Loa, Hawaii each year (first graph below) is strongly affected by sea surface temperature (SST) variations (second graph below), which are in turn mostly a function of El Nino and La Nina conditions (third graph below):
Click for larger images
Click for larger image
During a warm El Nino year, more CO2 is released by the ocean into the atmosphere (and less is taken up by the ocean from the atmosphere), while during cool La Nina years just the opposite happens. (A graph similar to the first graph also appeared in the IPCC report, so this is not new). Just how much of the Mauna Loa Variations in the first graph are due to the “Coke-fizz” effect is not clear because there is now strong evidence that biological activity also plays a major (possibly dominant) role (Behrenfeld et al., 2006).
The direction of causation is obvious since the CO2 variations lag the sea surface temperature variations by an average of six months, as shown in the following graph:
So, I keep coming back to the question: If warming of the oceans causes an increase in atmospheric CO2 on a year-to-year basis, is it possible that long-term warming of the oceans (say, due to a natural change in cloud cover) might be causing some portion of the long-term increase in atmospheric CO2?
I decided to run a simple model in which the change in atmospheric CO2 with time is a function of sea surface temperature anomaly. The model equation looks like this:
delta[CO2]/delta[t] = a*SST + b*Anthro
Which simply says that the change in atmospheric CO2 with time is proportional to some combination of the SST anomaly and the anthropogenic (manmade) CO2 source. I then ran the model in an Excel spreadsheet and adjusted an “a” and “b” coefficients until the model response looked like the observed record of yearly CO2 accumulation rate at Mauna Loa.
It didn’t take long to find a model that did a pretty good job (a = 4.6 ppm/yr per deg. C; b=0.1), as the following graph shows:
Click for larger image
The best fit (shown) assumed only 10% of the atmospheric CO2 increase is due to human emissions (b=0.1), while the other 90% is simple due to changes in sea surface temperature. The peak correlation between the modeled and observed CO2 fluctuation is now at zero month time lag, supporting the model’s realism. The model explained 50% of the variance of the Mauna Loa observations.
The best model fit assumes that the temperature anomaly at which the ocean switches between a sink and a source of CO2 for the atmosphere is -0.2 deg. C, indicated by the bold line in the SST graph, seen in the second graph in this article. In the context of longer-term changes, it would mean that the ocean became a net source of more atmospheric CO2 around 1930.
A graph of the resulting model versus observed CO2 concentration as a function of time is shown next:
If I increase the anthropogenic portion to 20%, the following graph shows somewhat less agreement:
Click for larger images
There will, of course, be vehement objections to this admittedly simple model. One will be that “we know the atmospheric CO2 increase is manmade because the C13 carbon isotope concentration in the atmosphere is decreasing, which is consistent with a fossil fuel source.” But has been discussed elsewhere, a change in ocean biological activity (or vegetation on land) has a similar signature…so the C13 change is not a unique signature of fossil fuel source.
My primary purpose in presenting all of this is simply to stimulate debate. Are we really sure that ALL of the atmospheric increase in CO2 is from humanity’s emissions? After all, the natural sources and sinks of CO2 are about 20 times the anthropogenic source, so all it would take is a small imbalance in the natural flows to rival the anthropogenic source. And it is clear that there are natural imbalances of that magnitude on a year-to-year basis, as shown in the first graph.
What could be causing long-term warming of the oceans? My first choice for a mechanism would be a slight decrease in oceanic cloud cover. There is no way to rule this out observationally because our measurements of global cloud cover over the last 50 to 100 years are nowhere near good enough.
And just how strenuous and vehement the resulting objections are to what I have presented above will be a good indication of how politicized the science of global warming has become.
REFERENCES
Michael J. Behrenfeld et al., “Climate-Driven Trends in Contemporary Ocean Productivity,” Nature 444 (2006): 752-755.
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RW (02:35:27) :
The isotope card has been burned since it was noted that part of the algae/ plankton prefer the C13 way. There is lots and lots of them in the oceans.
Sure people emit a puny 6 Gigatones to the atmospheres 750Gigatones, not even 1%, and within the noise of the system. http://en.wikipedia.org/wiki/Carbon_cycle
With the increase in temperatures and subsequent increase in CO2 the flora has flourished up by 30%. Notice that vegetation give 650 gigatons to the atmosphere, that is it is circulating in its respiration expiration and decay 100 times more than our puny 6 gigatons. It could clean its teeth with that. 30% increase would mean that the flora generates almost 200 gigatons, to our puny burning 6 extra. still noise to the signal.
So it is not that there is no effect from anthropogenic CO2. It is that it is too small and flooded by the flora and the ocean exhalations.
Unless you are not able to understand big numbers, ( one, two thee, many) this should be evident.
Why CO2 falls after the beginning of an ice age, rises after initial warming coming out of an ice age
A Wally Broecker article, based upon analysis of sediment cores, found that after the earth cools substantially after the initiation of an ice age, the drier and windier conditions off Patagonia cause about 50 times more dust from the southernmost part of South America to blow into the southern ocean. The dust has minute amounts of iron, which in fact does fertilize the ocean, enough to draw down tens of PPM of CO2, but over a time scale of several thousand years.
While some of the increase in CO2 drawdown ends up on the seabed in the form of diatomic/planktonic detritus, most of it occurs as an increase of dissolved CO2 in the ocean itself (the detritus gets processed by bacteria before it sinks very far, releasing the CO2 back into the water).
The process of CO2 drawdown takes so long because it requires that high CO2 waters only a few hundred meters or less from the surface near Antarctica are exported to deep waters, in a vertical “elevator” process that occurs in that part of the world. From these southern ocean deep waters, deep currents gradually redistribute the CO2-rich waters around the world.
Whenever this CO2 rich water gets to surface, it releases CO2 back to the atmosphere. So in order to get the full increase in oceanic CO2, the entire ocean must be saturated with the excess CO2. At this point, there is a steady state balance of input and output of CO2.
When the earth finally warms again, the input fertilization process slows back to the “normal” we see today — e.g., little natural wind blown iron fertilization off Patagonia — but the output process continues for a few thousand years until the tens of PPM of CO2 are all back in the atmosphere.
Fertilization does work, but it took thousands of years. To attempt to get something like 40 PPM sequestered in this manner, in say 100 years, would likely create hypoxic and anoxic dead zones because it would take place in one place, the southern ocean, where surface waters are exported to depth and there is a relative lack of iron. So I’ve become reluctantly convinced that iron fertilization isn’t the solution to too much atmospheric CO2 (yes, I agree, we don’t know how much is too much; if I didn’t agree, I wouldn’t be reading this blog). Whether we should fertilize the ocean is not the main topic of this post, however.
Thus one point of this post is to point out why CO2 levels rose and fell with the ice ages, and why there was a substantial lag of about 800 years before the CO2 dropped enough for us to measure it (going into the ice age) and rose by that much (going out). This doesn’t negate a cooling and warming role, as a positive feedback in each direction, but I don’t think Broecker or anyone else has tried to model how much of an additional feedback the changes in CO2 levels, subsequent to going into or out of an ice age, actually occurred.
The other point is to say that on the short time scales of decades that Roy Spencer analyzes, more CO2 gets into the ocean because with more in the atmosphere, the partial pressures of CO2 in air vs. CO2 in water cause something like half of the CO2 in the air to be dissolved in the oceans, even with slight increases in SSTs. I’m a bit surprised Spencer didn’t know that, he clearly knows his own field very well.
Mike Bryant (00:26:42) : That AIRS animation makes it absolutely inconceivable that man can have anything to do with such massive swings.
http://airs.jpl.nasa.gov/story_archive/CO2_Increase_Sep2002-Jul2008/
I reached a different conclusion. I thought it looked quite possible that we have a SYMBIOTIC process here: NH cities produce CO2 in the winter months, alongside the CO2 from winter forests, which is then guzzled by happy taiga and other temperate vegetation in the summer months. We know the biosphere has increased, and that the Sahel is greener.
However, Spencer’s evidence of a tiny proportion of human contribution to CO2 increase is important. What most people forget is the sheer size of the annual flux, the huge quantity of CO2 in the oceans, the temperature-dependent solubility of CO2, and the biosphere’s ability to grow, to take in any extra CO2, both as plants and as marine shells.
Carl Wolk (14:48:56) :
I am not an “AGW troll.” I find it disconcerting that if I doubt one argument proposed by one skeptical scientist, I am assumed to agree with AGW theory. I am what you would call a “skeptic,” but I think he is wrong on this issue. “Skeptics” have begun (especially on this blog) to leap onto any theory that would contradict AGW theory; this is not skepticism.
——
First, my apology. My troll statement was not aimed at you, but to all the warmers generally on this thread.
As for the alternate theories on this blog, I agree. It isn’t necessary to show what the source of climate change is. Only necessary to demonstrate that AGW isn’t it.
——
For Spencer’s proposed mechanism to make sense, we have to reject ice-core data in light of the medieval warm period. Instead we turn to Beck’s reconstruction. I find it odd that the chemical measurements show such rapid, and changing CO2 content, yet as soon as Mauna Loa begins to take measurements the slope turns very flat and does not change from a general linear rise. Are there any modern CO2 chemical measurements that we could use to compare against Mauna Loa data?
So really, this debate is focused on the wrong place. Spencer’s proposition is impossible if we accept ice-core data. It might be correct if we accept Beck’s chemical data.
——
I tend to reject the ice core data used by Callandar because it does not appear to be representative. There are also legitimate questions about the accuracy of ice cores. I think that the historical data from chemical analysis may only be useful to demonstrate the deficiencies in Callandars CO2 construction. At best we may only be able to say that we don’t know what the historical values really were, and consequently the claims that the current levels are higher than ever, are without merit. And I’m also suspicious of the Mauna Loa data.
As long as the government money is going into AGW research, it’s going to be difficult to do the kind if studies that will show what the reality is.
Also, while it appears counter intuitive, it is entirely possible for the co2 content in the atmosphere and the c02 content in the oceans to rise at the same time. The oceans are constantly absorbing and releasing CO2, and only a minor change in ocean temperature would change the balance.
While Dr. Spencers analysis may be a bit iffy, it did generate a lot of questions and it may actually be correct in a somewhat simplistic manner
I would suspect that we agree more than we disagree.
anna v (05:28:07) :
RW (02:35:27) :
The isotope card has been burned since it was noted that part of the algae/ plankton prefer the C13 way. There is lots and lots of them in the oceans.
Sure people emit a puny 6 Gigatones to the atmospheres 750Gigatones, not even 1%, and within the noise of the system. http://en.wikipedia.org/wiki/Carbon_cycle
With the increase in temperatures and subsequent increase in CO2 the flora has flourished up by 30%. Notice that vegetation give 650 gigatons to the atmosphere, that is it is circulating in its respiration expiration and decay 100 times more than our puny 6 gigatons. It could clean its teeth with that. 30% increase would mean that the flora generates almost 200 gigatons, to our puny burning 6 extra. still noise to the signal.
Anna, you have misread the diagram, the black numbers are the amount stored and the purple numbers are the fluxes.
The warming trend (or any temperature trend for that matter) is a statistical number, not the data. For every spike and fall in the noise, weather events coincide that are directly tied to natural processes. Give me any spike or fall and I will send you scurrying to archived weather reports (jet stream data, oceanic conditions, weather fronts, etc) where you will find the explanation quite clear and easy to understand. If this can be done for EVERY spike and fall (which some say is weather), and it can, how can you jump to the conclusion that the statistical trend line (which some say is climate) that is created from these weather events is caused by something else (CO2, Sun, the goddess in the cave)? That is a leap even Evil Knievel would not have attempted. Folks, the weather noise creates the very artificial trend line, therefore the trend line is not climate. Furthermore, the trend line is too removed from cause and affect to be useful in ascribing any cause to such a noisy data set.
[Phil. I’m growing weary of your attacking Dr. Spencer and others from the shadows without having the courage (as he does) to put your name to your words. So until you do, no more posts (about Spencer) from you. You are a scholar, and this sort of behaviour wouldn’t be tolerated in your own institution, in a professional critique of the work of other colleagues, or even in letters to administration, so I’m not going to give you a free ride to critique anonymously here. Science and scholars should be held to a higher standard. You say “Dr. Spencer’s math is wrong”, prove it and put your name and institution on it. I’ll even offer a guest post position for you. Otherwise don’t post again. – Anthony Watts]
UPDATE: Phil, your claim of anonymous review doesn’t hold water, because it is not written in private to a reviewer, your comments are published for the world to see. In peer review, the public does not see the critiques, only the reviewer. The decision and offer stands. You are welcome to have your own guest post here at WUWT, refuting Dr. Spencer, provided you have the courage to put your name on your work. – Anthony Watts
BTW Phil. I should add that I have no issue with you refuting others who post under partial names or handles here, my concern is only that Dr. Spencer be treated fairly. If you are going to claim falsification of his essay, and do it publicly here, you need to put your name on it. It would be no different if you wrote a rebuttal letter to a journal. If you didn’t sign your name to it, they would not publish it. – Anthony Watts
While I don’t like Phil. worth a darn(he’s called me bad names) I think he should be allowed to continue to post. My objection to him is along the lines of his telling the truth, and nothing but the truth, but not the whole truth. You can rely on the specifics of what he says, but you cannot fundamentally rely on what he says because he will simply refrain from mentioning anything that goes against his point of view. Thus, he is fundamentally untrustworthy. I understand your point, Anthony, and agree with it, but still find much value in Phil.’s input. Glad I don’t have to decide.
============================================
REPLY: He’s welcome to post on other threads. My issue applies only to his claims about Spencer. We are so often beat up over the issue of peer review, and yet here is somebody who is part of a major academic institute of higher learning, fully willing to circumvent the traditional peer review process, and to do so publicly rather than privately, while claiming falsification from a position of anonymity. That won’t wash here. – Anthony
Ah, Anthony, I see wisdom in your 8:21:30 post.
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wattsupwiththat (08:21:30) :
It would be no different if you wrote a rebuttal letter to a journal. If you didn’t sign your name to it, they would not publish it. – Anthony Watts
I have a comment about the review process. I agree that the reviewer [if she/he so chooses] should be anonymous during the review process. After [and if] a paper has been accepted, the reviewers and their review should be made public. Some journals at least thank the reviewer publicly. But the whole exchange should be public [in the electronic supplement that almost all journals provide], so that one can see how thorough the review was, and by whom. This also helps the reviewer to get credit for the [unpaid] service provided, which can be a substantial amount of work in itself.
“My objection to him is along the lines of his telling the truth, and nothing but the truth, but not the whole truth.”
I wonder if AGW apologists don’t consider the Good greater than one good, the Truth. Its like a difference between believing mankind basically good and ameliorable versus iniquitous and finite.
Phil. (06:43:38) :
Anna, you have misread the diagram, the black numbers are the amount stored and the purple numbers are the fluxes.
Possible.
Well,vegetation, 610, atmosphere 720 and anthropogenic 5.5 are all in black on my laptop screen. Are you saying that the 5.5 ( if it is purple) should be compared to what? 60 +60 +92? Not as small a percentage but still quite small.
RE: RW (02:35:27) :
***“There is still no convincing evidence of the CO2=heating hypothesis, of course”
..except that the very existence of a greenhouse effect proves it beyond doubt, of course.***
The greenhouse effect keeps our temperature fairly steady or balanced on the earth. The question is: “does adding CO2 and other greenhouse gases change the temperature and by how much?”
1) NOBODY has to date MEASURED the amount or percentage that CO2 increases or has increased the global temperature. The “beyond all doubt” is a saying, but not a proof. One way to look at it is that if CO2 is the main factor in temperature increase, then the global temperature must increase EVERY year with the increase varying in amount due to natural causes. The temperature has not increased every year, so CO2 cannot be the dominant factor. The second question that should be addressed is Steve McIntyre’s one that IPCC has not addressed: 2) Where is the detailed engineering quality calculation of the effect that doubling the CO2 will have on the earth’s temperature?
You can check David Archibald’s paper as one reference of how the effect of greenhouse gasses decrease logarithmically.
***For those who still seek to argue that all the CO2 is from ‘natural’ sources: please consider Occam’s Razor. ***
The “skeptic” scientists are not saying that ALL the CO2 is from natural sources. Please check this.
***We have these simple observations: 1. fossil fuel burning has released a vast amount of CO2 in the atmosphere; 2. fossil fuel CO2 has a lower 13C content than both atmospheric and oceanic CO2; 3. atmospheric CO2 concentrations began to rise when fossil fuel burning began to rise; 4. the 13C content of atmospheric CO2 began to drop when fossil fuel burning began to rise. You can see some nice figures here***
Check the latest studies – The 13C is not only from fossil fuels. The increase in CO2 in the atmosphere is not all due to fossil fuels
***No reasonable person looks at these facts and concludes anything other than fossil fuel burning is the cause of the rise in atmospheric CO2. ***
What you are saying is that any reasonable person will conclude that fossil fuel burning is the only cause of the increase in CO2.
That is getting to be a tired old AGW alarmist line. Was fossil fuel burning the cause of the 1000+ ppm ages ago as well?
***I have no idea what Roy Spencer’s motivation is, for publicising such nonsense, but the advancement of science is definitely not what he’s trying for here.***
Sorry, but your criticisms are unfounded. Dr. Spencer has done a lot of good work.
He also stated that this paper was for discussion purposes.
On another thread
http://wattsupwiththat.com/2009/05/10/solar-scientist-ken-tapping-no-sign-of-the-new-cycle-yet/#more-7754
anna v has been trying to convince me that the rise in co2 is being pushed by temperature with 2 different mechanisms
one with a response of 6months and a longer 800year deep ocean driven response.
I pointed out that the fast response would have been active in the entry/exit from ice age and therefore there should be a simultaneous (within the accuracy of the icecore record) change in CO2 with temperature as is she suggests now happening. But according to most [anti agw] the ice record shows this 800 year lag.
Anna then suggests that the fast response is a transient driven by change in temperature.
This in my view is not valid as the last 10 years have been cooling and the CO2 should therefore be dropping – the co2 record changes are detectable monthly.
Can anyone shed a light on the reason why the fast response CO2 increase is invisible in the ice core records please.
Bill,
My understqanding is that the ice cores are not exactly like tree rings where each individual year can be isolated uniquely. So my guess is that the faster changes are being integrated by the nature of the resolution of the ice layers. The process Roy is asserting is beyond ice core resolution (I believe)
Pehaps somone “in the business” can elaborate on that.
George
“”” RE: RW (02:35:27) :
***“There is still no convincing evidence of the CO2=heating hypothesis, of course”
..except that the very existence of a greenhouse effect proves it beyond doubt, of course.*** “””
Well RW you are a great problem solver. For a start the “greenhouse effect” isn’t really a greenhouse effect at all; green houses work via a different mechanism.
But more importantly; before you get to pointing fingers at CO2; you have to get past all the “greenhouse warming” that has already been done by the main atmospheric GHG component which is water vapor.
There’s very little warming energy left for CO2 to play with after water vapor gets through with the energy spectrum.
So NO ! the very existence of the greenhouse effect does not prove the existence of a CO2-warming link; doesn’t even hint at it, let alone prove it beyond a reasonable doubt.
And yes I do believe that CO2 molecules can and do absorb long wave infra red radiation; that does not equate to raising the global temperature.
Lucy Skywalker (12:41:52) :
Thank you very much – just when I thought I had an understanding of this issue!
bill (09:51:23)
THis may not answer your question, but the scale of temperature into and out of the glaciations is on the order of 10-12 deg. C. We haven’t had that amount of change yet, thus would not see CO2 response for that extreme a temperature shift. I know all the focus is on greenhouse effects and atmospheric composition, but it seems to me that the ocean temperature drives the atmospheric temperature due to the difference in mass. The greenhouse effect just slows the heat loss for the planet. IMO, the greenhouse effect is probably maxed out, and can’t become more of an isulator to allow temperature to climb more than another couple of degrees ever. I think we can be a lot cooler but not a lot warmer. The miniscule changes we have seen in the past century are lost in the noise level. By the time we start dropping 2-3 deg we’ll have a completely different world within a generation.
http://i40.tinypic.com/2pquhee.jpg
George E. Smith (10:14:38) :
My understqanding is that the ice cores are not exactly like tree rings where each individual year can be isolated uniquely. So my guess is that the faster changes are being integrated by the nature of the resolution of the ice layers. The process Roy is asserting is beyond ice core resolution (I believe)
No – the entry into / out of an ice age should create a visible shift in the CO2 concentration easily within the measurement limits of ice cores
There should be a near instantaneous change in co2 when the temperature changes maintained at least for the time the temperature is changing or as I would expect a permanent step change until the temp returns to normal.
There is NONE – why?
George E. Smith says:
George: Yes, those calculations have to be done but they already have been. And, it is such settled science that even Roy Spencer and Richard Lindzen accept the value for the radiative forcing of ~3.8 W/m^2 (give or take ~10%). [Where they part company with most of the rest of the scientific community is on the issue of how feedbacks operate to go from the forcing to the temperature change.]
Steve Keohane says:
Actually, the global temperature change was about half that. The numbers that you quote, presumably from the ice core graphs that you’ve seen, represent the temperature changes in the polar regions which evidence suggests are roughly double the globally-averaged temperature changes.
There is no evidence that I know of that this is the case. In fact, the dependence of temperature on concentration is expected to be approximately logarithmic…which is why people talk about how much change is produced by a doubling of concentration. (For a logarithmic function, the amount of change due to each doubling is a constant.)
Furthermore, going back millions of years, there are past climates that were considerably warmer than our current climate.
George E. Smith (10:14:38) :
My understqanding is that the ice cores are not exactly like tree rings where each individual year can be isolated uniquely.
Pretty much they are, yes. Except near the bottom of the cores where the pressure has compressed the rings too much. For that part, a model of the compression with depth is used to get the age.
http://www.sciencelearn.org.nz/contexts/icy_ecosystems/sci_media/images/ice_core_showing_annual_rings
Further to George E. Smith (10:23:33) & Leif Svalgaard (12:16:17) who have responded to bill (09:51:23):
I’ve been following the interesting exchange between anna v & bill in the other WUWT thread. An exercise I think would help bill here:
Time-integrate monthly dCO2/dt at varying bandwidth (i.e. 1mo, 2mo, 3mo, 4mo, …). Note particularly what happens at multiples of 12. Consider related insight in conjunction with George’s & Leif’s comments.
Also, in reviewing anna v’s arguments, be careful when inferring-from-context whether she is referring to CO2 or dCO2/dt.
A final suggestion would be to question your own assertions about time-invariant best-lags. To gain related intuition, you might want to try some windowed time-integrated cross-correlation analyses.
I also recommend similar time-integration exercises for Pamela Gray due to the nature of comments appearing at Pamela Gray (06:44:40).
A related reference:
T.F.H. Allen & T.W. Hoekstra (1992). Toward a unified ecology. Columbia University Press, New York.
This book draws attention to the nature of very serious research errors stemming from inattentiveness to the influence of spatiotemporal heterogeneity on parameter estimates across spatiotemporal scale. A study that fails to investigate the influence of summary scale on parameter estimates in the presence of spatiotemporal heterogeneity is at-best incomplete and at-worst severely misleading.
“What could be causing long-term warming of the oceans? My first choice for a mechanism would be a slight decrease in oceanic cloud cover. There is no way to rule this out observationally because our measurements of global cloud cover over the last 50 to 100 years are nowhere near good enough.”
Indeed Albedo is to climate science, in what an egg is to theology.