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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JFA in Montreal (06:40:33)
“Those new flash ads bring my browser to a very slow pace, forces me to view them, can’t scroll, can’t switch windows.
They are detestable.”
I found what *seems to be a solution to multi-minute hangs: I discovered that I can relieve the (seemingly-permanent-at-times) hangs by grabbing-&-dragging the scroll-knob (right margin). (Attempting to scroll via mouse-wheel seems to fail.)
RE: Phil. (09:25:32) :
**His model has flaws anyway, for example the SST term should at least have a dependence on [CO2] as well.**
Where does that come from? An AGW model?
SST does not depend on CO2. CO2 is more likely to be related to an increase in SST.
Gilbert:
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.
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.
The certainty that some people have here about the mass balance is belied by the sheer guesswork involved. When you look at the calculations you realize you can make up any story you like because you can fit a bus in the error bars.
I’ve seen estimates of anthropogenic emissions from 7 Gt to 27 Gt all from seemingly reputable sources. Whether 7 or 27 though the assumed lost-in-sink percentage of that is always assumed to be 50%. If that seems ludicrous it’s because it is. The 50% is clearly just a dogma that doesn’t depend on any actual numbers.
It’s widely acknowledged though that our emissions are roughly about 3% of the total CO2 flux. New scientist shows a graphic of the carbon exchange:
http://www.newscientist.com/data/images/ns/cms/dn11638/dn11638-4_738.jpg
ie 440 Gt going in and out from land and 260 Gt going in and out from sea. Humans cause 26 Gt from fossil fuels and 6 Gt from land use. Well that +6 is wrong for a start because the earth is known to be greening. Likely it should be -6. And of course the fossil fuel part may be as low as 7 Gt. But anyway, just look at the sheer size of the fluxes compared to our tiny contribution.
So in order for for us to affect things, bearing in mind the huge likelihood of greater than 3% error in any of the flux numbers, we have to prove that the increase in the air is from man due to us disturbing the balance of nature. I find the argument surreal at this point: The system can’t cope with an extra 3%? There is no real evidence of this except that CO2 is increasing and so are temperatures. Which is, of course a silly circular argument because the temperature might cause the CO2 rise. The other evidence rests on iffy isotope ratio ideas. The carbon 14 argument was abandoned even by the IPCC and the carbon 13 argument was exposed as wrong-headed by Spencer. We also have the ice-cores telling us one thing about past CO2 but other geological evidence (ignored by the IPCC) telling us the opposite.
So all that are left are those iffy hand calculations with massive error bars and the a priori assumption that the increase is not natural. So no, it’s not obvious that the ocean is a net sink. Not unless you are either totally innumerate or just plain want to believe it.
JamesG (15:41:54) :
Thanks JamesG for that great explanation. I suspected that the 50% argument was a wild guess and likely bogus.
Nick Stokes,
One of many articles and studies acknowledging the huge increase in biomass over the last 20 years:
http://earthobservatory.nasa.gov/Features/GlobalGarden/
You also might want to spend a little time on the CO2Science site for all the PEER REVIEWED papers that you appear to be missing.
RW,
and exactly who was measuring the ratio of C13 in the oceans about 200 years ago??
HAHAHAHAHAHAHAHAHA
Oh yeah, paleo studies. Done by Mann and friends??
Let’s take this seriously for a moment. 200 years ago there is a SHARP DROP. Now, would you please explain to all of us, who was burning all the coal and petroleum that you would have us believe caused this sharp drop 200 years ago??
Please try to open your mind a tad and read some of the better submissions above that realistically bring into question the C13/Anthropogenic connection.
Carl Wolk,
you might want to look up the current CO2 data in cities. There are huge diurnal variations that exceed 500ppm peak in many of them.
What needs to be understood is that CO2 is NOT well mixed in the atmosphere. Around sources the measurements will regularly be much higher than the isolated measuring stations now in vogue. In fact, ALL those stations have strict standards that throw out measurements that are outside certain standards. This is to prevent mistakes in procedure or things like Volcano eruptions (see Mauna Loa), or odd wind patterns that bring CO2 saturated air from an inconvenient location (downtown anywhere) or a warming body of upwelling water or…, to the pristine measurement site.
Basically, those chemical measurements taken back then could not be duplicated now because the current levels would probably be much higher!!!!!! Why the warmers hyperventilate over them is pretty pitiful. It also shows how ugly they are when you consider that they are maligning some great scientists with their claims of poor practices and shoddy work just to try and shore up THEIR shoddy, misleading work.
Now, they can argue forever whether it is anthropogenic or natural, BUT, there is a heck of a lot more CO2 flux than is presented in their toy models.
Phil,
why should SST have a dependence on CO2??
Are you heating or cooling large amounts of CO2 and pumping it into the bottom of the ocean and letting it percolate up????
Amazing what odd little nuggets one finds.
In the paper above “earth observatory” the authors report that plant growth in the tropics was stimulated by “less cloud over and higher solar radiation”.
If so I imagine the oceans in the tropics also warmed from the same effect.
Kindest Regards
JamesG says:
Oh dear…What you probably have seen are estimates of 7 Gt carbon and estimates of 27 Gt of CO2. To convert between one and the other you have to multiply or divide by (44/12) since C has an atomic weight of 12 and CO2 has a molecular weight of 44. Your statement serves as a good example of how people here lead themselves astray and then mistakenly assume it is the scientists rather than themselves that are being dogmatic or incorrect.
The point is that there is a lot of carbon that cycles between the oceans, atmosphere, and biosphere…But, as the ice core record shows, these fluxes roughly balance. (When they don’t, as when we are going in and out of glacial cycles, the rate of change of CO2 levels in the atmosphere is still much smaller than it has been over the last century.) We are rapidly liberating a store of carbon that has been locked away from the atmosphere, oceans, and biosphere for tens to hundreds of millions of years.
In addition to the accounting (which is not as iffy as you thought once you realize the distinction between Gt of C and Gt of CO2), there is direct evidence that the ocean waters are becoming more saturated with carbonic acid as CO2 dissolves into them.
By the way, here is a summary of what is generally understood by scientists in regards to CO2, along with references into the literature: http://www.radix.net/~bobg/faqs/scq.CO2rise.html
kuhnkat (17:45:30) “It also shows how ugly they are when you consider that they are maligning some great scientists with their claims of poor practices and shoddy work just to try and shore up THEIR shoddy, misleading work.
I have seen many examples of such administrative practice first-hand. It is not science – it is politics — disgraceful politics.
JamesG,
There’s not much doubt about the amount of C burnt. carbon fuels are costly, and tracked by an army of accountants. The figures come from bodies like the EIA. You’re 27Gt is almost certainly data on CO2 produced, not C burnt. 7.5Gt C makes 27.5 Gt CO2. Burning is increasing rapidly, because of industrialisation in Asia. The latest EIA figure is 29195 Gt CO2 for 2006 (=7962 Gt C). There’s about another 5% from cement production.
The loss isn’t “assumed to be 50%”. Again, the Gt CO2 in the atmosphere is quite well known, so no assumption is needed. The IPCC AR4 has a FAQ on this topic (Chap 7), and they say 55%.
Joel Shore,
I would like to congratulate you on your new calm and straightforward comments. I am sure I am not the only one to notice the “new” you. There is still no convincing evidence of the CO2=heating hypothesis, of course, let alone any reason to believe that there are catastrophes related to it. You are starting to sound like a scientist instead of an agenda-driven firebrand.
Thanks for your effort, it is appreciated,
Mike
RE: Joel Shore (19:31:24) :
**By the way, here is a summary of what is generally understood by scientists in regards to CO2, along with references into the literature: http://www.radix.net/~bobg/faqs/scq.CO2rise.html**
The person who summarized that is not an expert in the field by his own admission.
He essentially just noted the AGW point of view.
I would give more credence to Spencer, Pielke, CO2Science, etc.
Gerald Machnee (14:45:04) :
RE: Phil. (09:25:32) :
**His model has flaws anyway, for example the SST term should at least have a dependence on [CO2] as well.**
Where does that come from? An AGW model?
Routine Physical chemistry, related to Henry’s Law, rather than:
dCO2/dT ≃ 4.6*SST+0.1*Anthro (which in the form Spencer used it has arithmetic errors anyway) the first term should be of the form a(SST,[CO2]).
oms (08:44:10) :
yet we observe that sea level is roughly the same everywhere. Hard to believe that all this water can flow around the world so quickly!
That is gravity that is keeping the levels constant. The consistency moves very very slowly and stays locally. Floods in Italy do not muddy the seas in Greece. There is no universal force, as gravity for water, around the globe for CO2. And AIRS data show that there is no direct mixing
http://airs.jpl.nasa.gov/story_archive/CO2_Increase_Sep2002-Jul2008/
Steve Keohane (09:33:00) :
In the western hemisphere, it looks like Alaska and Canada are the big emmiters. This makes no sense to me, as things are just beginning to thaw from winter, from non-industrial, low-density habitation areas. The only thing I can imagine is a loss of snow and ice releasing CO2 from under the same. I suppose all the underwater and underground species have been respirating all winter, and that might be released.
Part of it is the surface heating of the waters too, snow and ice will have CO2 absorbed in them too released with the melt suddenly. Considering that ground measurements give much larger CO2 concentrations, that will be a factor too. Is there a biologist in the house? Do burgeoning flora emmitt more CO2?
All of the tundra ponds are emitters of CO2 and methane, because of the amount of organic matter that that drains into them. However, I doubt that the amount would be comparable to human sources in inhabited regions and the peaks should be in summer, when temperatures are higher. Unlike oceans, inorganic carbon in lakes is mainly controlled by dissolved organic carbon from the water shed rather than atmospheric sources.
Concerning human CO2 emissions, the numbers are precise, within plus or minus 2% of the total. A book on “The carbon cycle” is available on Google books. You can see detailed listings of all of the various sources. I don’t have the author handy, but found it by searching (in google scholar) under “ratio of fossil fuel consumption and atmospheric CO2 increase”
anna v (20:59:58) :
Then it’s interesting that the equalizing cause for sea level (pressure gradient) also affects gases in a mixture. Without the floods in Italy muddying the seas in Greece…
The role assigned to CO2 in the CAGW morality play is laughable. It’s as if the Royal Shakespeare Company had asked Adam Sandler to play the title role in King Lear.
anna v,
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/
Mike
anna v (21:18:25) “Considering that ground measurements give much larger CO2 concentrations, that will be a factor too. Is there a biologist in the house? Do burgeoning flora emmitt more CO2?”
That would be soil organisms. I can’t give you any numbers (without researching them) – but I won’t hesitate to say the respiration peak should occur in summer (at high latitudes).
“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.
Robert Kral, from ages ago:
“the world has been both much warmer and much colder than it is now, before the emergence of humans and after. Since everything that we’re observing now is clearly within the bounds of natural variability, why is it necessary to invoke human causation? In fact, why is it not specious to do so before carefully eliminating all possible natural causes?”
This argument is a little bit like saying that if you were found dead in the middle of a road, and a car with a dent in its bonnet is stopped right by you, but you were less than 122 years old at the time of your death, then it would be reasonable to say that because your age was not outside the bounds of natural variability, there was no need to invoke human causation in your death. CO2 is a greenhouse gas, and its concentrations are rising sharply. Even if temperatures on Earth had varied in the past between absolute zero and 50,000K, that would not change these two facts, and it would not change the fact that increasing greenhouse gas concentrations are currently driving up temperatures.
For those who still seek to argue that all the CO2 is from ‘natural’ sources: please consider Occam’s Razor. 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
No reasonable person looks at these facts and concludes anything other than fossil fuel burning is the cause of the rise in atmospheric CO2. You are instead trying to claim that all the fossil fuel CO2 is simply vanishing, that oceanic CO2 is somehow changing its isotopic composition of its own volition, and that this miraculously changed CO2 began appearing in the atmosphere just when fossil fuel use began to rise, but was completely unrelated.
Given that oceanic CO2 content is rising, you also need to believe in another, as yet unspecified source which is more than replenishing oceanic CO2 losses to the atmosphere, but is again somehow completely unrelated to the vast amount of CO2 released by fossil fuel burning. These arguments are physically impossible. You hardly need to be a scientist to see that. 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.
Kuhnkat,
OK, I did look on CO2Science. They featured this paper on global terrestrial carbon uptake in the 80’s and 90’s. They cited NEP values, which measure addition to global biomass, but not allowing for loss by burning or agricultural use. In other words an upper bound on C accumulation in the biosphere.
They gave the 90’s NEP figure at 1.36 Gt/yr. A rise from the 80’s, but as said, it is reduced by fire etc. Still, it isn’t going to absorb our 8+ Gt/yr fossil fuel emission.