Guest Post by Willis Eschenbach
There seem to be a host of people out there who want to discuss whether humanoids are responsible for the post ~1850 rise in the amount of CO2. People seem madly passionate about this question. So I figure I’ll deal with it by employing the method I used in the 1960s to fire off dynamite shots when I was in the road-building game … light the fuse, and run like hell …
First, the data, as far as it is known. What we have to play with are several lines of evidence, some of which are solid, and some not so solid. These break into three groups: data about the atmospheric levels, data about the emissions, and data about the isotopes.
The most solid of the atmospheric data, as we have been discussing, is the Mauna Loa CO2 data. This in turn is well supported by the ice core data. Here’s what they look like for the last thousand years:
Figure 1. Mauna Loa CO2 data (orange circles), and CO2 data from 8 separate ice cores. Fuji ice core data is analyzed by two methods (wet and dry). Siple ice core data is analyzed by two different groups (Friedli et al., and Neftel et al.). You can see why Michael Mann is madly desirous of establishing the temperature hockeystick … otherwise, he has to explain the Medieval Warm Period without recourse to CO2. Photo shows the outside of the WAIS ice core drilling shed.
So here’s the battle plan:
I’m going to lay out and discuss the data and the major issues as I understand them, and tell you what I think. Then y’all can pick it all apart. Let me preface this by saying that I do think that the recent increase in CO2 levels is due to human activities.
Issue 1. The shape of the historical record.
I will start with Figure 1. As you can see, there is excellent agreement between the eight different ice cores, including the different methods and different analysts for two of the cores. There is also excellent agreement between the ice cores and the Mauna Loa data. Perhaps the agreement is coincidence. Perhaps it is conspiracy. Perhaps it is simple error. Me, I think it represents a good estimate of the historical background CO2 record.
So if you are going to believe that this is not a result of human activities, it would help to answer the question of what else might have that effect. It is not necessary to provide an alternative hypothesis if you disbelieve that humans are the cause … but it would help your case. Me, I can’t think of any obvious other explanation for that precipitous recent rise.
Issue 2. Emissions versus Atmospheric Levels and Sequestration
There are a couple of datasets that give us amounts of CO2 emissions from human activities. The first is the CDIAC emissions dataset. This gives the annual emissions (as tonnes of carbon, not CO2) separately for fossil fuel gas, liquids, and solids. It also gives the amounts for cement production and gas flaring.
The second dataset is much less accurate. It is an estimate of the emissions from changes in land use and land cover, or “LU/LC” as it is known … what is a science if it doesn’t have acronyms? The most comprehensive dataset I’ve found for this is the Houghton dataset. Here are the emissions as shown by those two datasets:
Figure 2. Anthropogenic (human-caused) emissions from fossil fuel burning and cement manufacture (blue line), land use/land cover (LU/LC) changes (white line), and the total of the two (red line).
While this is informative, and looks somewhat like the change in atmospheric CO2, we need something to compare the two directly. The magic number to do this is the number of gigatonnes (billions of tonnes, 1 * 10^9) of carbon that it takes to change the atmospheric CO2 concentration by 1 ppmv. This turns out to be 2.13 gigatonnes of carbon (C) per 1 ppmv.
Using that relationship, we can compare emissions and atmospheric CO2 directly. Figure 3 looks at the cumulative emissions since 1850, along with the atmospheric changes (converted from ppmv to gigatonnes C). When we do so, we see an interesting relationship. Not all of the emitted CO2 ends up in the atmosphere. Some is sequestered (absorbed) by the natural systems of the earth.
Figure 3. Total emissions (fossil, cement, & LU/LC), amount remaining in the atmosphere, and amount sequestered.
Here we see that not all of the carbon that is emitted (in the form of CO2) remains in the atmosphere. Some is absorbed by some combination of the ocean, the biosphere, and the land. How are we to understand this?
To do so, we need to consider a couple of often conflated measurements. One is the residence time of CO2. This is the amount of time that the average CO2 molecule stays in the atmosphere. It can be calculated in a couple of ways, and is likely about 6–8 years.
The other measure, often confused with the first, is the half-life, or alternately the e-folding time of CO2. Suppose we put a pulse of CO2 into an atmospheric system which is at some kind of equilibrium. The pulse will slowly decay, and after a certain time, the system will return to equilibrium. This is called “exponential decay”, since a certain percentage of the excess is removed each year. The strength of the exponential decay is usually measured as the amount of time it takes for the pulse to decay to half its original value (half-life) or to 1/e (0.37) of its original value (e-folding time). The length of this decay (half-life or e-folding time) is much more difficult to calculate than the residence time. The IPCC says it is somewhere between 90 and 200 years. I say it is much less, as does Jacobson.
Now, how can we determine if it is actually the case that we are looking at exponential decay of the added CO2? One way is to compare it to what a calculated exponential decay would look like. Here’s the result, using an e-folding time of 31 years:
Figure 4. Total cumulative emissions (fossil, cement, & LU/LC), cumulative amount remaining in the atmosphere, and cumulative amount sequestered. Calculated sequestered amount (yellow line) and calculated airborne amount (black) are shown as well.
As you can see, the assumption of exponential decay fits the observed data quite well, supporting the idea that the excess atmospheric carbon is indeed from human activities.
Issue 3. 12C and 13C carbon isotopes
Carbon has a couple of natural isotopes, 12C and 13C. 12C is lighter than 13C. Plants preferentially use the lighter isotope (12C). As a result, plant derived materials (including fossil fuels) have a lower amount of 13C with respect to 12C (a lower 13C/12C ratio).
It is claimed (I have not looked very deeply into this) that since about 1850 the amount of 12C in the atmosphere has been increasing. There are several lines of evidence for this: 13C/12C ratios in tree rings, 13C/12C ratios in the ocean, and 13C/12C ratios in sponges. Together, they suggest that the cause of the post 1850 CO2 rise is fossil fuel burning.
However, there are problems with this. For example, here is a Nature article called “Problems in interpreting tree-ring δ 13C records”. The abstract says (emphasis mine):
THE stable carbon isotopic (13C/12C) record of twentieth-century tree rings has been examined1-3 for evidence of the effects of the input of isotopically lighter fossil fuel CO2 (δ 13C~-25‰ relative to the primary PDB standard4), since the onset of major fossil fuel combustion during the mid-nineteenth century, on the 13C/12C ratio of atmospheric CO2(δ 13C~-7‰), which is assimilated by trees by photosynthesis. The decline in δ13C up to 1930 observed in several series of tree-ring measurements has exceeded that anticipated from the input of fossil fuel CO2 to the atmosphere, leading to suggestions of an additional input ‰) during the late nineteenth/early twentieth century. Stuiver has suggested that a lowering of atmospheric δ 13C of 0.7‰, from 1860 to 1930 over and above that due to fossil fuel CO2 can be attributed to a net biospheric CO2 (δ 13C~-25‰) release comparable, in fact, to the total fossil fuel CO2 flux from 1850 to 1970. If information about the role of the biosphere as a source of or a sink for CO2 in the recent past can be derived from tree-ring 13C/12C data it could prove useful in evaluating the response of the whole dynamic carbon cycle to increasing input of fossil fuel CO2 and thus in predicting potential climatic change through the greenhouse effect of resultant atmospheric CO2 concentrations. I report here the trend (Fig. 1a) in whole wood δ 13C from 1883 to 1968 for tree rings of an American elm, grown in a non-forest environment at sea level in Falmouth, Cape Cod, Massachusetts (41°34’N, 70°38’W) on the northeastern coast of the US. Examination of the δ 13C trends in the light of various potential influences demonstrates the difficulty of attributing fluctuations in 13C/12C ratios to a unique cause and suggests that comparison of pre-1850 ratios with temperature records could aid resolution of perturbatory parameters in the twentieth century.
This isotopic line of argument seems like the weakest one to me. The total flux of carbon through the atmosphere is about 211 gigtonnes plus the human contribution. This means that the human contribution to the atmospheric flux ranged from ~2.7% in 1978 to 4% in 2008. During that time, the average of the 11 NOAA measuring stations value for the 13C/12C ratio decreased by -0.7 per mil.
Now, the atmosphere has ~ -7 per mil 13C/12C. Given that, for the amount of CO2 added to the atmosphere to cause a 0.7 mil drop, the added CO2 would need to have had a 13C/12C of around -60 per mil.
But fossil fuels in the current mix have a 13C/12C ration of ~ -28 per mil, only about half of that requried to make such a change. So it is clear that the fossil fuel burning is not the sole cause of the change in the atmospheric 13C/12C ratio. Note that this is the same finding as in the Nature article.
In addition, from an examination of the year-by-year changes it is obvious that there are other large scale effects on the global 13C/12C ratio. From 1984 to 1986, it increased by 0.03 per mil. From ’86 to ’89, it decreased by -0.2. And from ’89 to ’92, it didn’t change at all. Why?
However, at least the sign of the change in atmospheric 13C/12C ratio (decreasing) is in agreement with with theory that at least part of it is from anthropogenic CO2 production from fossil fuel burning.
CONCLUSION
As I said, I think that the preponderance of evidence shows that humans are the main cause of the increase in atmospheric CO2. It is unlikely that the change in CO2 is from the overall temperature increase. During the ice age to interglacial transitions, on average a change of 7°C led to a doubling of CO2. We have seen about a tenth of that change (0.7°C) since 1850, so we’d expect a CO2 change from temperature alone of only about 20 ppmv.
Given all of the issues discussed above, I say humans are responsible for the change in atmospheric CO2 … but obviously, for lots of people, YMMV. Also, please be aware that I don’t think that the change in CO2 will make any meaningful difference to the temperature, for reasons that I explain here.
So having taken a look at the data, we have finally arrived at …
RULES FOR THE DISCUSSION OF ATTRIBUTION OF THE CO2 RISE
1. Numbers trump assertions. If you don’t provide numbers, you won’t get much traction.
2. Ad hominems are meaningless. Saying that some scientist is funded by big oil, or is a member of Greenpeace, or is a geologist rather than an atmospheric physicist, is meaningless. What is important is whether what they say is true or not. Focus on the claims and their veracity, not on the sources of the claims. Sources mean nothing.
3. Appeals to authority are equally meaningless. Who cares what the 12-member Board of the National Academy of Sciences says? Science isn’t run by a vote … thank goodness.
4. Make your cites specific. “The IPCC says …” is useless. “Chapter 7 of the IPCC AR4 says …” is useless. Cite us chapter and verse, specify page and paragraph. I don’t want to have to dig through an entire paper or an IPCC chapter to guess at which one line you are talking about.
5. QUOTE WHAT YOU DISAGREE WITH!!! I can’t stress this enough. Far too often, people attack something that another person hasn’t said. Quote their words, the exact words you think are mistaken, so we can all see if you have understood what they are saying.
6. NO PERSONAL ATTACKS!!! Repeat after me. No personal attacks. No “only a fool would believe …”. No “Are you crazy?”. No speculation about a person’s motives. No “deniers”, no “warmists”, no “econazis”, none of the above. Play nice.
OK, countdown to mayhem in 3, 2, 1 … I’m outta here.
Alternatively perhaps precipitation has increased and is washing the CO_2 out of the atmosphere at an increased rate.
Rules for Discussion: A masterstroke! It would change this whole field if adherence to this could be guaranteed. How about enshrining that somewhere on the main WUWT page or making it an editorial policy, or something? It should be nailed up by moderators at the beginning of climate debates everywhere — and STRICTLY enforced.
As for your article, Willis, I find little that is controversial in it, but I would have liked to see more discussion of the empirical evidence for the high proportion of human emissions in the CO2 resident in the atmosphere today. From what I read of isotope studies, emissions comprise a small fraction. This, of course, does not mean that they have not CAUSED the rise in CO2, as the gas is continually being consumed, absorbed and re-emitted by the seas, plant life and geological system, none of which care which CO2 molecules they are absorbing. With the flux in and our of the natural system more-or-less in balance, the addition of human emissions should have the effect of increasing the total but it will be distributed into the various sinks and replaced with naturally occurring CO2, thus it should comprise a smaller proportion of the whole than one would think. I imagine one could use the emission numbers versus the empirical values of resident emitted CO2 to infer something about actual (as opposed to theoretical) absorption rates. I wonder if this has been done.
P Berkin,
Here’s another CO2 chart to keep you from worrying. And another.
I left out forest fire suppression as a reason for bump in CO2 in recent years. As was discovered a few decades ago forest fire suppression actually has the opposite effect of what Smokey the Bear wanted – preservation of our forests. Suppressing forest fires allows combustables to accumlate near ground level setting the stage for truly massive fires that can’t be controlled and are so hot that it destroys old growth trees which would have otherwise survived the lesser more frequent fires. When those old growth trees go up in smoke you get a century’s worth of CO2 locked up in the wood released into the atmosphere.
While land use changes and forest fire suppression are still anthropogenic in origin its not the fossil fuel bogeyman that everyone is focused on and wants to control and it’s not the US that is the big offender. The political drive behind this whole CAGW hoax is ained at two things
1) Taking over control of fossil fuel use and thus taking over the factor that literally fuels the economic growth of industrialized nations. It’s a power play.
2) Putting a damper on the US economic and military superpower status. Anything that can’t be blamed on the US is of no interest to the rest of the world or even US domestic self-loathers. Thus we hear next to nothing about the effects of black carbon (soot) produced by dirty diesel engines, slash & burn agriculture, heating of homes with wood and even dung, lack of particulate filters on coal burning power plants, and other assorted soot sources. You see, starting with the Clean Air Act of 1963 the US has dramatically reduced the amount of soot it pumps into the atmosphere. No other country in the world has come close to matching that effort. Moreover we regulate our logging industry such that their harvest methods either don’t denude the land or require planting of young trees to replace the old ones removed and we pretty much no longer use wood as source of fuel and instead much of becomes lumber used in contruction of durable structures where the carbon in the wood remains locked in the wood for a hundred years after harvest. On top of that we now use control burns that don’t destroy old growth forest but rather serve to remove fuel before it accumulates into disastrously hot fires that kill big trees.
Willis,
You have to go and publish that book.
Note: There is no need to write it, as I think you have most of it written already.
40 shades
The worst kind of worry is worrying about what to worry about.
Once one reaches that point it’s too late to really worry about anything.
Unless you’re worried about not worrying enough.
But then there’s a risk of worrying about worrying too much and it becomes a worry about being lost in a circle of worry.
With AGW, worry has become the devil’s elixir.
Willis
I will echo the comment Steve Hempell made on the rocket science site. In my case I like the math included at that site, but the downloads are long, and I long since gave my analysis programs such as MATLAB away. So I’m limited to EXCEL and VB.
Looking at your initial 1000 year plot, one can make a case for man’s increase in CO2, “eyeballing” the apparent rise since the inception of the “industrial revolution” ~1750.
I’m in the process of completing a book, most of which is irrelevant to this discussion, except for the section discussing mass migration of people from 500 B.C. to 500 A.D., and what effects weather/climate had to do with it. Which has led to trying to better understand temperatures prior to the 1850 point. In looking at the temperature records, there seems to be very little data, if any, outside of central and western Europe.
One of my thoughts were, if the industrial age started in Europe, emitting all that soot and CO2, might one see a rise there first?
The following are averaged temperature anomaly charts reflecting the earliest records from Central England, DeBilt and http://www.rimfrost.no/
sources:
http://www.imagenerd.com/show.php?_img=lt-temp-1650-2008-1-Rxrdy.gif
http://www.imagenerd.com/show.php?_img=lt-temp-1750-2008-4-EyvXd.gif
http://www.imagenerd.com/show.php?_img=lt-temp-1800-2008-14-9ZSv8.gif
http://www.imagenerd.com/show.php?_img=lt-temp-1850-2008-27a-UtBGD.gif
http://www.imagenerd.com/show.php?_img=lt-temp-1900-2008-50a-PhLn0.gif
I used a Fourier convolution, or spectral lo-pass filter, with a cut off at a 40 year period. From my rought view, I don’t see anything happening until more global temps are started to be included from 1900 on, and any warming showing up only after about 1975.
I liked the Fourier as it included the end points, if used correctly, and allows correlation of other physical inputs which have periodic, or almost periodic secular cycles.
Any thoughts?
Britannic no-see-um says:
June 7, 2010 at 3:49 am
How trivial or significant is the direct additional respiratory and food production CO2 emission produced by increases in human longevity and population density since medieval times?
____________________________________________________________________________
The termites beat us hands down.
“According to the journal Science (Nov. 5, 1982), termites alone emit ten times more carbon dioxide than all the factories and automobiles in the world. Natural wetlands emit more greenhouse gases than all human activities combined. (If greenhouse warming is such a problem, why are we trying to save all the wetlands?)”
Termites emit ten times more CO2 than humans. Should we cap-and-tax them?
“The 0.03% CO2 content of the atmosphere is minimal and has less impact and is lower in volume than, for example, methane given off by termites (who outweigh humans by 30x). ” http://globalwarminghoax.wordpress.com/2006/08/01/global-warming-is-a-hoax-invented-in-1988/#comment-9266
Correct me if I’m wrong, but doesn’t thawing permafrost release the same Carbon isotope as fossil fuel (12C)? Could thawing permafrost as part of a natural warming cycle account for part of the CO2 increase?
“Nick Stokes says:
June 7, 2010 at 2:52 am
Willis,
A good explanation of many things, especially the e-folding time. But I don’t agree with your calculation of the 31 year period. I think you have calculated as if each added ton of CO2 then decays exponentially back to the 1850 equilibrium level. But the sea has changed. It is no longer in equilibrium with 280 ppm CO2. Of course it has its own diffusion timescale, and lags behind the air in pCO2. You could think of the decay as being back to some level at each stage intermediate between 1850 and present.
If you apply that process to the emission curve, you’ll match the airborne fraction with a slower decay (longer time constant) where the decay has less far to go.”
No, Nick. Exponential decay towards an increasing equilibrium level would need a smaller time constant for the observed rate of sequestration, not a larger one.
Richard S Courtney says:
June 7, 2010 at 3:58 am
That is what I call using your little grey cells.
Come on Willis! That pre historic CO2 proxy is low pass filtered!
From Segalstad;
http://folk.uio.no/tomvs/esef/esef3.htm
And;
http://folk.uio.no/tomvs/esef/esef5.htm
stevengoddard says:
June 7, 2010 at 6:09 am
Claims that cement manufacture introduce significant CO2 are the work of people who don’t understand science. Sadly that includes the US Government. When the cement is mixed with water, it absorbs the CO2 back from the atmosphere. Without CO2 the cement would never harden.
http://en.wikipedia.org/wiki/Portland_cement
“Carbon dioxide is slowly absorbed to convert the portlandite (Ca(OH)2) into insoluble calcium carbonate. “
GeoFlynx-
The cement industry is thought to contribute about 5% of human Co2 emissions. Co2 is released in the manufacture of cement by the calcination of lime and the combustion of fuels in a kiln process. Portland and other hydraulic cements will continue to react with Co2 in the air and further “cure”. The reaction with atmospheric Co2 continues after initial hardening and is very slow often continuing for hundreds or thousands of years. In no way does this continued uptake of Co2 equal the amount of Co2 required in the cement’s manufacture. Hydraulic cements will harden quite well without absorbing Co2 from the atmosphere. Cements of this type are well suited to applications underground and underwater.
If CO2 is the primary driver of temperature changes today, what would the CO2 content be in the atmosphere historically under a reverse prediction of the IPCC temp-CO2 connection?
Note: I recognize that this argument has a limited application, as it is of a “if a then b, if b not necessarily a” type. However, is it not reasonable that for at least the post 1850 period this argument could be applied? Warmists say that most of the post-industrial warming is AG-CO2 related. Certainly the date of AGW showing up is variable, depending on how much change is desired for alarm purposes. 1850 is used as one reference point, though 1945 and 1975 are also used. The warmist argument also holds that recent changes in astrophysical input are not significant to this warming. A reversal of the prediction would show when solar influences MUST have become significant. CO2 as a significant forcing cannot be JUST in the current era. Or it will show that CO2 measurements by ice core are unreliable … which goes against the warmist view of how global temperatures are moderated even recently.
James Sexton:
“Hmm, perhaps for many, but for others it would seem including religiosity would be appropriate.”
Again, I agree, but my suggestion was for those people searching for a term, which does not imply further connotation. Reality sometimes has to move over for politeness! Besides, faith and belief are terms which can be thrown back at us. That is all I have to say. GK
Willis:
I’m very impressed by your work.
But to all the people playing “average temperature”, and in the spirit of trying to do GOOD ENGINEERING WORK… “average temperature” is a FICTION and MEANINGLESS. Here is why: Go to any online psychometric calculator. Put in 105 F and 15% R.H. (Heh, heh, I use the old English units, if you are fixated on Metric, get a calculator!) That’s Phoenix on a typical June day.
Then put in 85 F and 70% RH. That’s MN on many spring/summer days.
What’s the ENERGY CONTENT per cubic foot of air? 33 BTU for the PHX sample and 38 BTU for the MN sample.
So the LOWER TEMPERATURE has the higher amount of energy.
Thus, without knowledge of HUMIDITY we have NO CLUE as to atmospheric energy balances. “Average temperature” discussions, EVEN IF THE PROXIES ARE VALID (something I strongly doubt…take the O18 proxy, geologist use it to trace coastal outfalls from tropic areas, where tropic thunderstorms enrich it. That’s it, period…INVALID as a temperature proxy. KING’S NEW CLOTHES argument, just because it’s been repeated long enough and loud enough does not mean it is true!) the problem is, in terms of atmospheric energy, they are MEANINGLESS.
Max
“”Smokey says:
June 7, 2010 at 9:09 am
Interesting CO2/Temp chart.
Smokey says:
June 7, 2010 at 9:18 am
P Berkin,
Here’s another CO2 chart to keep you from worrying. And another.””
Thanks Smokey, it’s nice to have a reality check.
Measurements like ‘tons’ etc, are meant to fool.
Percentages are all that matter, and out of that very small percentage,
how much is ‘man made’ and how much of that can we really do about it?
I’ve currently interested in the work of Dr Christine Jones, retired soil scientist. She recently made the following statement.
“This year Australia will emit just over 600 million tonnes of carbon. We can sequester 685 million tonnes of carbon by increasing soil carbon by half a per cent on only two per cent of the farms. If we increased it on all of the farms, we could sequester the whole world’s emissions of carbon.”
http://www.abc.net.au/landline/content/2008/s2490568.htm
Perhaps our agriculture methods are having more effect on CO2 levels than we realise.
Interesting piece Willis. Your conclusions on post-1850 CO2 trends seem fair, but I don’t think that the pre-1850 CO2 data that you show in Figure 1 tell the whole story. Back in 1996 I did an analysis of the available CO2 proxy data, most of which were from ice cores, and the results differed form what you show. The relevant figure from this paper is shown in my blog (http://suddenoaklifeorg.wordpress.com) here:
http://suddenoaklifeorg.wordpress.com/2010/01/10/the-potential-role-of-peatland-dynamics-in-ice-age-initiation/
Note that I found a slight but significant downward trend in CO2 concentrations during the few thousand years leading up to 1850. So I’m curious why the difference in these data sets?
P. Berkin says:
June 7, 2010 at 9:04 am
I was starting to worry a bit . . . then I re-drew the top graph with the y-axis going from 0 – 1,000,000 and I stopped worrying.
I am not a climate scientist, by the way.
However YOU ALREADY KNOW THE TRICK : By making “convenient graphs” you’ll scare housewives and politicians will praise you, and, what is more important in these days, you’ll eat tomorrow and you won’t lose your house the day after tomorrow.
Nice work Willis. It’s notable to find the number of responses that are not on point. perhaps you should add a 7th rule about being germane, or about admitting when one is wrong. Anyway, I should catalogue the various ways in which people avoided simple agreement with your hypothesis. Also I want to reserve special criticism for those people who still do not understand what the TRICK is. The trick has been covered in detail many times, but I will do it one more time. the TRICK consists of this
1. truncation of a proxy series. {not always required}
2. Splicing a temperature series onto that.
3. smoothing the result.
4. failing to indicate that this is what you did by NOT distinguishing the data sources.
The KEY ELEMENTS are these
1. performing a mathematical operation on the two datasets that regards them as measures of the same thing. The smooth.
2. presenting the result AS IF it were data from from one source.
Folks Willis has not performed the trick. I give him a F on climate science trickery.
Anyway, to respond simply. I agree with you willis. There is more C02 in the atmosphere today than in 1850. The best explanation for that is man’s activities.
I’ve seen nothing in the way of argument that would lead me to seriously question either of those.
The perfect linearity of the pre-eighteenth century curve is a surprise. Against that background, the more recent trend stands out like a sore thumb. I am not greatly concerned with that, however, because you cannot jump from there to argue that it warms the world if you cannot explain the mechanism. The IPCC starts out with the Svante Arrhenius formulation but this does not give as much warming as they want so they fudge it by adding positive feedback from water vapor. This is how they get their alarming forecasts. But now we have two reasons to doubt them: Willis has come out with a “Thermostat Hypothesis” whereby tropical clouds and thunderstorms actively regulate the temperature of the earth. And now Ferenc Miscolczi (E&E, vol. 21, no. 4, 2010) has a theory according to which water vapor feedback is not positive as IPCC would have it but strongly negative which prevents any temperature excursions caused by excess greenhouse gas concentrations. He also points out that for all practical purposes the oceans are an essentially infinite source of water vapor. Which means that AGW simply cannot happen. And fretting about an increase in the partial pressure of atmospheric CO2 is nothing more than an unnecessary distraction designed to make us fear that coming warming it is supposed to bring.
“The termites beat us hands down.
“According to the journal Science (Nov. 5, 1982), termites alone emit ten times more carbon dioxide than all the factories and automobiles in the world. ” Ha! That’s where all the extra CO2 is coming from — the termites in the south having a field day since air condidtioning made living there viable.
Actually, I have a bit of a problem: All this CO2 rising seems to be post 1950 but the industrial age started in the early 1800’s. Parts of England, France, Poland and Germany were covered in soot from the coke and steel production by the 1870’s and the US was ramping up to speed in Pennsylvania but the increases shown n the charts don’t reflect this. Since the 1960’s on, manufacturing has become cleaner with scrubbers, etc – even with China and India. The biggest change that can see to human fuel useage that follows the CO2 usage charts is the automobile.
toho says:
June 7, 2010 at 9:43 am
“No, Nick. Exponential decay towards an increasing equilibrium level would need a smaller time constant for the observed rate of sequestration, not a larger one.”
Yup. that is exactly right. Depending on what level of CO2 from land use change you believe (Willis is taking a high value), the decay constant ranges from about 31 years to about 43 years (if you believe a much lower land use contribution, as several recent studies suggest). In any case, the IPCC projections of CO2 decay rates are way to low.
Overall, a reasonable posting.
A few thoughts:
“Now, how can we determine if it is actually the case that we are looking at exponential decay of the added CO2? One way is to compare it to what a calculated exponential decay would look like.”
This presumes there is only one sink, and that it is infinite, as another commenter noted. There are multiple sinks, of limited capacity, acting on different timescales. What Willis has captured is most likely the upper 700m of the ocean, a fast acting sink, as is well known by the already apparent rise in carbon content of this volume. If a sink is fast acting, it is likely to reach an equilibrium point quickly; so, expecting the same rate of decay into the future is problematic.
under “Issue 3. 12C and 13C carbon isotopes”
I think Willis is making the mistake of thinking of CO2 absorption by the ocean as a one-way trip. A decent analogy is to imagine a host of tennis players knocking green balls to each other; the balls are CO2 molecules and the net is the boundary between water and air. The court is littered with balls. If you dump a bunch of orange balls onto one side, they don’t simply ‘decay’ to the other side; in a little while, an equilibrium is reached where there are orange and green balls on both sides.
@Slioch:
“the reaction whereby CO2 is most readily absorbed is NOT by simple reaction with water”
I would expect that CO2 would have to be absorbed by the water before it could react with the other chemicals in the water. How much gas is absorbed in water is largely a function of temperature and relative concentrations; no chemical reaction is required there. What you have shown is better labeled as how an increase in CO2 content leads to a decrease in pH, rather than as how CO2 is absorbed.
Ian H,
“I find it interesting that the sequestration rate seems to be getting larger – it is trending above the exponential line. ”
That’s about the opposite of how I see the graph. Looking at the end points and the rate of change of the slopes, calculated airborne is less than actual airborne, and calculated absorbed is higher than actual absorbed. I suspect Willis had to tweak the decay rate vary carefully in order to be able to overlap the curves without the differences between the rates of change (and the rates of change of the rates of change) (derivative and second derivative for those familiar with calculus) being readily apparent.
“Richard S Courtney says:
June 7, 2010 at 2:43 am”
Many thanks for your detailed schema!