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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Slightly OT but germane to regulation of CO2 is an excerpt from an inter-agency memo authored by Office Management Budget:
“The amount of acknowledged lack of understanding about the basic facts surrounding [greenhouse gases] seem to stretch the precautionary principle to providing regulation in the face of unprecedented uncertainty,”
This reported today in the Wall Street Journal as EPA Administrator Lisa Jackson appears to about face on “Cap N’ Trade.” But without $646 billion in carbon trade revenue – how will the Administration pay for programs?
http://online.wsj.com/article/SB124214922088511421.html
Is it the physical properties of oceans that alter C02 absorption or is it biological? I could be backwards, but I’m having trouble understanding how a warmer ocean (regardless of why it’s warmer now) absorbs less CO2 than a cooler ocean, especially if the absorption is through marine life. Wouldn’t warmer temps increase plant life and therefore decrease C02? Either way it will be a glorious day if it is proven that this relationship is the main mechanism for CO2 fluctuations!!
Ahem, I shall get the criticisms over: Heretic! Unbeliever, Infidel!! Ok, that said this may be a very good way of seeing what Co2 actually is in our atmosphere.I’ve held that the Co2 content is from largely Oceanic heating.-Now that things are cooling off for whatever the reason,could we be seeing some stabilization or even decrease?-Due mainly to the Oceanic absorption of Co2…
Fantastic. I love it.
It will be interesting to see comment from others.
Well at least the world’s factories are contibuting their (small) amount of an increase in a gas that is plant food and will cause plant-life to flourish.
I don’t know if we crossed a magic threshold that could be with a certain CO2 level + lots of rain or not, last year the mullberry and hackberry trees in our backyard grew some jumbo-sized leaves that were quite a bit bigger than usual, our neighbor’s young walnut tree had leaves that looked like they were hit with a jumbo ray, and there’s early signs some trees in our yard could have huge leaves this year as well.
This is why I didn’t like it when I saw a picture of these things that are designed to take CO2 out of the air, the CO2 is helping out with the rain to create good-sized plant growth that’s more than normal behind our house and around a few other spots in our neighborhood.
How much clearer do you want to have your science served!
Great job, great conclusions.
Fantastic !!!
It is great to see how your 90-10 Model serves to hang the AGW Alarmists on their own petards !!!!
I wonder about the carbon cycle. The http://www.uwsp.edu/geO/faculty/ritter/geog101/textbook/earth_system/carbon_cycle_NASA.jpg picture shows that the amount to and from the oceans is only 50% more than the amount to and from land vegetation. Both are much higher than the fossil fuel and cement industries. Is this not a large component of the puzzle that this simple model excludes?
John M Reynolds
The ice core data shows long-term rises in CO2 following temperature increases and the short-term data shows CO2 lags surface temperate rises by 6 months. Now how can CO2 be causing the increases?
Here is something relevant which I prepared some time ago:
1) Take a container of, say, 10 litres, full of natural CO2 molecules (N) only.
2) Have an intake on one side and an outlet on the other.
3) Insert 9 molecules of N and one molecule of human CO2 (H) into the intake.
4) Allow time for mixing and remove 10 randomly selected molecules from the outlet.
5) Due to the size of the initial volume the chance of removing H is infinitesimal so the contents will then have an H molecule with all the rest being N molecules.
6) Repeat many many times and eventually the proportion of H molecules in the container will rise to 10% which is commensurate with the proportion of H amongst the molecules being put in.
What will have happened up to this point is that outgoing N molecules will have been replaced by incoming H molecules until 10% have been replaced so it’s now 90% N and 10% H but the total volume has remained the same.
Then this goes to the heart of the issue:
7) Add 1 litre of N to the container which will reduce the proportion of H then continue the process as before until the 10% proportion of H is restored.
8) Now we will have a larger total volume but still 90% N and 10% H
9) Note that the increase in volume came entirely from new N. The H molecules only got there by replacing molecules of N.
10) It would be tempting to say that the 10% increase in volume was caused by the introduction of the 10% H but in fact it was not.
Thus it is unsafe to suggest that in the real world the increase in total atmospheric CO2 was caused by anthropogenic input, even if the volume of H appears to be similar to the amount of increase in the total volume.
Anthony:
Sometime in the last year, you posted an article, (by Joe D’Aleo I believe – could be wrong as I’m going by memory). I tried to find it. No luck. Do you still have it? It would be nice to read that along side the above.
Thanks in advance.
I like this article, it explores something I’ve often had doubts about.
Also “the natural sources and sinks of CO2 are about 20 times the anthropogenic source” is a fact I use with agnostics
The CO2 balloon has major leaks. Temperature doesn’t seem to respond to the monotonic increasing of atmospheric concentrations of this trace gas. Understanding whatever it is that consistantly is overwhelming CO2 should go a long way towards understanding climate. The anthro contribution to the increasing levels of CO2 is miniscule, 3-4%. It seems we are wasting a lot of time and resources on a non-problem that certainly isn’t driving our climate.
A very interesting approach.
A question from a simple mind.
Are some of the CO2- extrapolations employed by IPCC assuming a 1% annual CO2 increase?
With the current rate , http://www.esrl.noaa.gov/gmd/ccgg/trends/
the annual rate of increase is in the 0.5-0.75% range, and apparently decreasing (as the total CO2 concentration is increasing).
Cassanders
In Cod we trust
I don’t think you’re actually saying 10% from an Anthropogenic source. b=.1 would represent 10% if a=.9, but since you have a=4.6 you’re actually saying that the Anthopogenic contribution is closer to 2 percent (2.13%). Increasing b to .2 means it’s a 4.17% contribution. a=4.6 would be a normalized to 97.87%. Your weighting variables are percentages only when your equation is normalized.
Anthropogenic CO2 is still rising while both temperature and global CO2 are decreasing. Why are we blamed for this again? Oh, yeah, that’s because Fat Albert said so…
Al prophesying
CO2 choking
cows farting
planets circling
Sun moving…
Oh Gosh!, barycenter!
sunspots disappearing
jet stream downing
cosmic rays falling
clouds growing
la nina dancing
Oh Gosh!, my head dizzying
Obama Administration Memo Warns of Harm to Economy if Greenhouse Gases Regulated through Clean Air Act
http://blogs.abcnews.com/politicalpunch/2009/05/obama-adminis-2.html
If the EPA goes forward with a finding of endangerment for all six greenhouse gases, the document warns, “it could be establishing a relaxed and expansive new standard for endangerment. Subsequently, EPA would be petitioned to find endangerment and regulate many other ‘pollutants’ for the sake of the precautionary principle (e.g., electromagnetic fields, perchlorates, endocrine disruptors, and noise).”
It is an interesting theory, and there certainly are mechanisms that can explain the cause and effect relationship. But the real test will be the models ability to predict CO2 rate of change going forward. The Achilles heal of the climate models is of course they seem much better at predicting the past than they are at predicting the future, since this model has a six month lag, it should only take a few years to vet the model and make sure it has staying power.
I wasn’t aware that anyone thought 100% of increases must be anthropogenic. That seems pretty illogical given the biosphere and the cyclical nature of… nature. There I go thinking logically again…
Roy, I’ve done a fair amount with this already, and I have a method to backsolve any variable so I can zero in on the parameters to match the curve (or change the model) to match it better than what you’re showing. It’s a lot more powerful than excel’s backsolver. If you want to email me a copy of your sheet I’ll show you what I mean and will email back the results…
I use it to match oscillation frequency / amplitude until I get best match with actual data (least squares), then project forward oscillations to get temperature estimates… Works with CO2. dCO2/DT is pretty drastic and very fast, leading me to think that the amount exchanged is huge (no matter what the temperature is at the moment) and the time constant is very short (i.e, the notion that residence time of CO2 is more than a few years is pure fantasy). 6 month lag peak to peak depends somewhat on the temp oscillation frequency (since if there was not an oscillation neither curve would have peaks)… Let me know if you’re interested… It should be possible to get a time constant out of the data (that too could be modeled to get the best fit TC)
Mr. Roy W. Spencer,
You have an easy to understand style of writing. Thank you for that,
A fellow Yooper
It makes sense to me but watch the AGW promoters attack Dr. Spencer with ad homs. They are getting desperate as more and more scientists and lay people are abandoning the side of the AGWers.
Well, there’s nothing new here. CO2 desorbing from oceans is one of the most classical positive feedbacks in global circulation models. End of the story.
REPLY: Which is the problem of alarmism in the first place, you never look beyond that, nobody wants to dig any deeper. “Man made CO2 is the cause, end of story”. As another psoter said: Get some integrity “Flanagan”. Look deeper instead of replaying talking points if you are capable. – Anthony Watts
Even the AGWers acknowledge that increased temperatures cause an increase in CO2 to be released from warmer oceans and thawing permafrost. So, that aspect of the argument is “settled”. It actually result in a negative feedback to their overall argument.
HOW STRONGLY DOES THE SUN INFLUENCE CLIMATE?
Since the middle of the last century, the Sun is in a phase of unusually high activity, as indicated by frequent occurrences of sunspots, gas eruptions, and radiation storms. Researchers at the Max Planck Institute for Solar System Research (MPS) in Katlenburg-Lindau (Germany) and at the University of Oulu (Finland) have come to this conclusion after they have succeeded in reconstructing the solar activity based on the sunspot frequency since 850 AD. To this end, they have combined historical sunspot records with measurements of the frequency of radioactive isotopes in ice cores from Greenland and the Antarctic. As the scientists have reported in the renowned scientific journal, Physical Review Letters, since 1940 the mean sunspot number is higher than it has ever been in the last thousand years and two and a half times higher than the long term average. The temporal variation in the solar activity displays a similarity to that of the mean temperature of the Earth. These scientific results therefore bring the influence of the Sun on the terrestrial climate, and in particular its contribution to the global warming of the 20th century, into the forefront of current interest.
http://earthobservatory.nasa.gov/Newsroom/view.php?id=25149
Sun warms oceans, oceans outgas CO2, simple, the sun becomes highly active then CO2 starts to increase. Less cloud more cloud, the sun is still the driver as it was at the end of the little ice age. 220ppm as average CO2 level is rubbish, Beck disproved that number.