Under the Volcano, Over the Volcano

Guest Post by Willis Eschenbach

In 2006, I lived for a year in Waimea, on the Big Island of Hawaii. From my house I could see the Mauna Loa Observatory (MLO). This observatory is the home of the longest continuous series of CO2 measurements we have. The recording station was set up by Dave Keeling in 1959, and has operated continuously ever since.

Figure 1. Mauna Loa Observatory ( 19.536337°N, 155.576248°W)

Here’s a view of the observatory from Panoramio:

Every time the subject of CO2 measurements comes up, people raise all kinds of objections to the Mauna Loa measurements. So I thought I’d start a thread where we can discuss those objections, and perhaps dispose of some of them.

Here are the objections that I hear the most:

1. The Mauna Loa results don’t measure the background CO2 levels.

2. You can’t get accurate CO2 measurements from samples taken on the side of an active volcano that is outgassing CO2.

3. The measurements from Mauna Loa are not representative of the rest of the world.

4. What about the Beck data, doesn’t it contradict the MLO data?

5. Keeling chose a bad location.

Before we get into those issues, let’s start by looking at the local meteorological conditions at the site. Mauna Loa is at an elevation of 3397 metres (11,140 ft) on the side of a 4,170 metre (13,680 ft) volcano way out in the middle of the Pacific Ocean. Because it is on an island, it gets the “sea breeze” in the daytime, and the “land breeze” in the nighttime.

These winds are caused by the differential heating of the land and the sea. Land heats up much faster than the ocean. So during the day, the warmer land heats the air, which rises. This rising air is replaced by air moving in from the surrounding ocean, creating the “sea breeze”.

At night, the situation is reversed. The land is cooler than the ocean. This cools the air. The cool air runs downhill along the slopes of the island and out to sea, creating the “land breeze”. Here’s a drawing of the situation:

Figure 2. Day and night breezes at Mauna Loa.

Now that we understand what is happening at Mauna Loa, let’s look at the objections.

1. The Mauna Loa results don’t measure the background CO2 levels. As you might imagine from Fig. 2, the CO2 measurements are taken only at night. Thus, they are measuring descending air that is coming from thousands of feet aloft. This air has traveled across half of the Pacific Ocean, so it is far from any man-made CO2 sources. And as a result, it is very representative of the global background CO2 levels. That’s why Keeling chose the site.

2. You can’t get accurate CO2 measurements from samples taken on the side of an active volcano that is outgassing CO2. This seems like an insuperable objection. I mean, Mauna Loa is in fact an active volcano that is outgassing CO2. How do they avoid that?

The answer lies in the fact that the volcanic gasses are very rich in CO2. At night, they are trapped in a thin layer near the ground by a temperature inversion.

To detect the difference between volcanic and background CO2, the measurements are taken simultaneously from tall towers and from near the ground, at intervals throughout the night. Background CO2 levels will be around 380 ppmv (these days), will be steady, and will be identical at the top and bottom of the towers. Volcanic gasses, on the other hand, will be well above 380 ppmv, will be variable, and will be greater near the ground than at the top of the towers.

This allows the scientists to distinguish reliably between volcanic and background CO2 levels. Here is a description of the process:

Air samples at Mauna Loa are collected continuously from air intakes at the top of four 7-m towers and one 27-m tower. Four air samples are collected each hour for the purpose of determining the CO2 concentration. Determinations of CO2 are made by using a Siemens Ultramat 3 nondispersive infrared gas analyzer with a water vapor freeze trap. This analyzer registers the concentration of CO2 in a stream of air flowing at ~0.5 L/min. Every 30 minutes, the flow is replaced by a stream of calibrating gas or “working reference gas”. In December 1983, CO2-in-N2 calibration gases were replaced with the currently used CO2-in-air calibration gases. These calibration gases and other reference gases are compared periodically to determine the instrument sensitivity and to check for possible contamination in the air-handling system. These reference gases are themselves calibrated against specific standard gases whose CO2 concentrations are determined manometrically. Greater details about the sampling methods at Mauna Loa are given in Keeling et al. (1982) and Keeling et al. (2002).

Hourly averages of atmospheric CO2 concentration, wind speed, and wind direction are plotted as a basis for selecting data for further processing. Data are selected for periods of steady hourly data to within ~0.5 parts per million by volume (ppmv); at least six consecutive hours of steady data are required to form a daily average. Greater details about the data selection criteria used at Mauna Loa are given in Bacastow et al. (1985). Data are in terms of the Scripps “03A” calibration scale.

There is a more detailed description of the measurement and selection process here.

As a result, the Mauna Loa record does accurately measure the background CO2 levels, despite the fact that it is on an active volcano. The samples that are identified as volcanic CO2 are not thrown away, however. They are used for analyses of the volcanic emission rates, such as this one (pdf).

3. The measurements from Mauna Loa are not representative of the rest of the world. Well, yes and no. The concentration of atmospheric CO2 varies by month, and also by latitude. Here is a “carpet diagram” of the changes by time and latitude.

Figure 3. A “carpet diagram” of CO2 distributions, by time and latitude.

Note that the swings are much greater in the Northern Hemisphere. Presumably, this is from the plants in the much larger land area of the Northern Hemisphere. However, the difference between the annual average of the Northern and Southern Hemispheres is small. In addition, there are smaller daily variations around the planet. An animation of these is visible here, with day by day variations available here.

Figure 4 shows is a typical day’s variations, picked at random:

Figure 4. Snapshot of the variations in tropospheric CO2. Note that the range is small, about ±1% of the average value.

In general, the different global records match quite closely. In addition to the Mauna Loa observatory, NOAA maintains CO2 measuring stations at Barrow, Alaska; American Samoa; and the South Pole. Here is a comparison of the four records (along with two methane records):

Figure 5. Comparison of the CO2 records from the four NOAA measuring sites.

As you can see, there is very little difference between the CO2 measurements at the four stations – two in the Northern Hemisphere, two in the Southern, two tropical, and two polar.

4. What about the Beck data, doesn’t it contradict the MLO data? In 2007, Ernst-Georg Beck published a paper called “180 Years Of Atmospheric CO2 Gas Analysis by Chemical Methods” (pdf).  In it, he showed a variety of results from earlier analyses of the atmospheric CO2. In general, these were larger than either the ice core or the MLO data. So why don’t I believe them?

I do believe them … with a caveat. I think that the Beck data is accurate, but that it is not measuring the background CO2. CO2 measurements need to be done very carefully, in selected locations, to avoid contamination from a host of natural CO2 sources. These sources include industry, automobiles, fires, soil, plants, the list is long. To illustrate the problems, I have graphed the Beck data from his Figure 13, against the Law Dome ice core data and the MLO data.

Figure 6. CO2 data from a variety of sources. White crosses are MLO data. Three separate ice core records are shown. Photo is of Mauna Loa dusted with snow (yes, it snows in Hawaii.) PHOTO SOURCE

There are several things to note about this graph. First, there is good agreement between the Law Dome ice core data and the MLO data over the ~ two decade overlap. Second, there is good agreement between the three separate Law Dome ice core datasets. Third, both the ice cores and the MLO data do not vary much from year to year.

Now look at the various datasets cited by Beck. Many of them vary quite widely from one year to the next. The different datasets show very different values for either the same year or for nearby years. And they differ greatly from both the ice core and the MLO data.

Because of this, I conclude that the Beck data, while valuable for showing ground level CO2 variations at individual locations, do not reflect the background CO2 level of the planet. As such, they cannot be compared to the MLO data, to the ice core data, or to each other.

5. Keeling chose a bad location. I would say that Keeling picked a very good location. It not only allows us to measure the background CO2 in a very accurate manner, it provides invaluable information about the amount of CO2 coming from the volcano.

My conclusion? Most of the records in the field of climate science are short, spotty, and not very accurate. We have little global historical information on ocean temperatures, on land temperatures, on relative humidity, on atmospheric temperatures, on hurricane occurrence and strength, or on a host of other variables. By contrast, the Mauna Loa CO2 records are complete since 1959, are very accurate, and are verified by measurements in several other locations.

I’m about as skeptical as anyone I know. But I think that the Mauna Loa CO2 measurements are arguably the best dataset in the field of climate science. I wouldn’t waste time fighting to disprove them, there are lots of other datasets that deserve closer scrutiny.

[UPDATE] A reader below has added another question, viz:

6. What about Jaworoski’s claim that the ice core data has had its age “adjusted”?

Jaworoski argues that the age of the air in the ice cores has been “adjusted” to make it align with the modern data. He says, for example, that the Siple ice core data has been moved forwards exactly 83 years to make them match the Mauna Loa data.

Dating the ice core data is problematic. We can date the ice itself pretty accurately, through counting layers (like tree rings) and through studying various substances such as volcanic dust that is trapped in the ice. However, dating the air is harder.

The difficulty is that the air is not trapped in the ice immediately. The pores in the “firn”, the snow that falls annually on top of the ice are open. Air can flow in and out.

As more and more snow falls over the years, at some point the pores close off and the air is trapped. So how long does it take for the pores in the firn to seal off?

Unfortunately, as in so many areas of climate science, the answer is … “depends”. It depends inter alia on how much snow falls every year, how much of that snow sublimates (changes from a solid to a gas) every year, and even the shape and size of the individual snowflakes.

The end result of all of this is that we end up with two ages for any given thin slice of an ice core. These are the “ice age” (how old the ice itself is), and the “air age” (how old the air trapped in the ice is). The ice is always older than the air.

The main variable in that is thought to be the annual snowfall. Unfortunately, while we know the current rate of annual snowfall, we don’t know the historical rate, particularly tens of thousands of years ago. So we use the concentration of an isotope of oxygen called “d18O” to estimate the historical snowfall rate, and thence the firn closing rate, and from that the air age.

Sounds a bit sketchy? Well … it is, particularly as we go way back. However, for recent data, it is much more accurate.

So to bring this back to real data, in the ice core data I showed in Fig. 5, the air is calculated to be 30 years younger than the ice for cores DEO8 and DEO8-2, and 58 years younger for the DSS core. Is this correct? I don’t know, but I do know that there are sound scientific reasons for the “adjustment” that Jaworowski objects to .

Finally, the existence of a thirty to sixty year difference in air and ice age doesn’t make much difference in the pre-industrial levels of CO2. This is because prior to about 1800, the level is basically flat, so an error in the air age dating doesn’t change the CO2 values in any significant manner.

FURTHER INFORMATION:

MLO Home Page

MLO Data Links

Greenhouse Gas & Carbon Cycle Research Programs

Trends in Atmospheric Carbon Dioxide

MLO Webcams

How we measure background CO2 levels on Mauna Loa

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Rhoda R

Thank you, Mr. Eschenbach, that answered many questions that I had about those CO2 measurements.

crosspatch

If it matters, I have no objection to the Mauna Loa CO2 observations. The thing is that I don’t think anyone has shown that increased CO2 has any detrimental impact on anything. So what if it is rising? Pine trees apparently love it. There is no evidence that it has had any significant climate impact to date as most of the temperature variation to day seems to be natural cyclical activity that goes on all the time.
The CO2 measurements are “interesting” but I wouldn’t worry all that much about them at this point. The additional CO2 is probably doing more good than harm.

Steven mosher

Thanx Willis.
since so many people see skeptics as anti science it would be instructive to point out the science that is accepted by skeptics. So many people waste their time with silly misinformed arguments

Don E

What about CO2 measurements from ice core samples and the like? I have heard it argued that because ice is not a closed system, those historical measurements are far from accurate. The CO2 level in the past could have been much higher (or lower).

pat

Mauna Loa is sporadically active. I never see out gassing unless it is active, less than once every 30 years or so. In that case, as the largest volcano on Earth, and largest active in the solar system, we all know when the shit has hit the fan and adjustments to the CO2 count can be made. Like shutting down the measures and getting out of Hilo.
It is, however down wind of a very active volcano, Kilauea Iki.
I suspect that much of the CO2 we now measure is because of oceanic out gassing, caused by global warmth. Whether this is really true is unknown and will not be known unless we see an unexplained decease in the same.

fredJ

Your post clarified some of my own misconceptions and I thank you for that.
However, the Mauna Loa data shows seasonal CO2 variation. Why would that be so? Is it due to tempeature variation? Could it be due to sea temperature changes? Is there a temperature record for the sampling points and is there a corresponding ocean temperature record for the surrounding area?

Chris L

Thank you Willis.
I was one who was once highly skeptical of the choice of this monotoring site.
Not just because of it being on “a volcano,” but rather an area of high volcanic activity also situated in the middle of warm waters.
That’s what so much of this is about. Knowing what data and observations we can be confident of, and building from that.

dr.bill

Very clear and informative presentation, Willis. I shall have to modify my previous thoughts on such matters.
/dr.bill

Having these objections about CO2 and MLO come up over and over again in various comment threads, the doubt they express sort of seeps into the whole thinking on this issue. Great to have them put to rest. Thanks Willis.
It would be interesting to contrast the sophisticated instrumentation, rigour of method, calibrations and accuracy of this set of measurements with some of the temperature measurements. For example we hear various things about the satellite measurements suffering instrument drift requiring correction. Are there weak points in some of these global measurements? And where are they?
There is a lovely Chinese proverb that says “Only he that has travelled the road knows where the holes are deep”. There is such a lot of time wasted by armchair travellers speculating about the location and size of ‘holes’ in climate data. We need to sure where the real holes are and ensure they are marked with a big ‘danger’ sign. Perhaps then the climate change road map can be shown to be so full of holes that it is not safe to travel.

Just a minor point. From my misspent (or I feel very well spent, but others differ) youth on tropical beaches, the breeze tends to go out until midday and then inland until some time in the night. I recall this well as we tended to wallow in the sea at the time the breeze stopped as the heat was too much.
We assumed from this that the land heats up during the day, and when it reaches the sea temperature the breeze stopped. It then reversed as the land became hotter than the sea. The reverse surely occurred at night, although we were not so aware as it was cooler (and we were probably less ‘observant’ for a number of reasons).
I am sure the same would happen here, so the explanation showing air flow down, and out to sea, in the evening is a tad simplistic and this would not occur until some time in the night. I suspect this is taken into account, however.
And I was told I would never learn anything bumming around on tropical beaches heh?

Nylo

Regarding the yearly variation in CO2 levels, a long time ago I noticed an interesting phenomenon. If you look at the Mauna Loa record, you will easily see that the yearly increment of CO2 is increasing, i.e. we are putting CO2 into the atmosphere more quickly now than in the 60’s. Everybody knows that, and the typical answer is “of course, we are emitting more”.
But we have increased our emissions roughly the same for all the months of the year, the industry doesn´t stop in the summer. We emmit about the same all year. However, if you look really carefully at the Mauna Loa data, you will see that the yearly increase has not happened in the same ammount for all the months of the year. Actually, only in (NH) winter do we see a difference compared to the 60’s. In the yearly oscillation, you will see that, on average, the reduction of atmospheric CO2 in the (NH) summer is the same that was happening in the 60’s, despite the fact that we emmit much more CO2 now in the summer than we did then. One would expect an everytime smaller reduction in CO2 levels according to our increasing emissions. However, it is only the winter increase that is getting bigger.
Many months ago I told this to Gavin Smith, as proof that the biosphere, the plants in the NH, are keeping up with our emissions. We emit more AND the plants are also able to absorb more, leading to the same summer reduction. But they can only do it in the growing seasons. However, Gavin told me that this was wrong, and the main reason was the bigger CO2 absorption in the southern oceans, especially in their winter (NH summer) when they are colder.
I couldn’t refute him, I really didn’t know which effect was more important. But now thanks to Willis I know that I WAS RIGHT. Because if the dominant effect was the absorption and release of CO2 by the souhtern oceans, then the yearly variations of CO2 should be bigger in the SH than in the NH. And in Willis’ graphs it is clearly understood that that’s not the case.
Thanks a lot, Willis.

Bart

Are the four records you show genuinely independent and unadulterated, or have they been adjusted in any way?

Tenuc

Thanks Willis, looks like the current measurements for CO2 levels are valid. However, I think the historic pre-industrial levels from the ice core data, quoted at 290ppmv, are open to argument as adjustments may have been made to ‘align’ them with the post 1959 Mauna Loa Observatory measurements (shades of the Briffa Tree Ring Data controversy perhaps?).
The following link to a statement by Prof. Zbigniew Jaworowski, (Chairman of Scientific Council of Central Laboratory for Radiological Protection, Warsaw, Poland) written for the hearing before the US Senate Committee on Commerce, Science, and Transportation has a good explanation of this potential issue, “Climate Change: Incorrect information on pre-industrial CO2 – March 2004”
http://www.warwickhughes.com/icecore/
I would be interested in your thoughts on this please.

John Finn

This will make an excellent link. Too often the ‘sceptic’ side gets distracted by muddled arguments about CO2 concentrations. The Beck measurements come up repeatedly. We need to accept that CO2 levels are increasing and that fossil fuel burning is almost certainly responsible for most of those increases.

Grumbler

Willis, another valuable essay. Keep up the good work.
However I disagree with your conclusion of suitable placement.
My internal alarm goes off once I hear that it’s really ok becuase the scientists use readings [and probably algorithms and computers] to distinguish the volcanic CO2 from the atmospheric CO2 readings.
“……This allows the scientists to distinguish reliably between volcanic and background CO2 levels.”
Isn’t a tenet of sceptical argument that it’s often the ‘adjustments’ that are the problem.
Further I’d like to know how the sensors in the towers read the CO2. I’m concerned about freezing as opposed to drying. If the air has been sufficiently filtered is it possible for super cooled water vapour to remain in the sample as the water has nothing to freeze on to? How is the CO2 seperated from other IR absorbers in the sample like methane ? I can’t believe the towers are as sophisticated as the lab where these things are hopefully done.
Anyway as I say very stimulating and much appreciated.
cheers David

DennisA

Willis ,
You say that MLO is complete since 1959. Wasn’t there a period when there were funding difficulties and perhaps the record had to be retro-fitted in the sixties?
Isn’t the homogenisation of Law Dome with MLO a little suspect? Aren’t we again looking at apples and kiwi fruit, CO2 trapped in ice cores compared with aerial measurement seems as illogical as mixing tree ring data and direct instrumental measurement for temperature records.
Do you dismiss Jaworowski and his criticism of Law Dome and ice cores in general, relating to CO2 measurement?
In your figure 5 chart it looks as if the “consensus” is achieved by all of them assessing the same data, that of Law Dome, in the same way that we get “consensus” in IPCC.
If Jaworowski is right then the consensus is wrong and more credence can be given to Beck.
Of course if it were not for the claims that CO2 is driving temperature upwards in contradiction of the cooling from the 40’s to the 80’s, when CO2 was increasing and a lack of warming currently, in the face of increasing CO2, then it would all be irrelevant.

Chris1958

A very welcome contribution which will help avoid needless distractions from the fundamental questions 🙂

John Finn

Willis
Just one question. Do you have any comments on the reliability of ice core data and, in particular, the issue of ‘diffusion’.

JohnH

Now can you ever imagine a post like this at RealClimate on say a paper By Steve McIntyre.
Just makes you think.

erin

Thankyou for the information. does the above data mean ice-core data gives accurate historical records?

Willis Eschenbach

Rhoda R says:
June 4, 2010 at 11:38 pm

Thank you, Mr. Eschenbach, that answered many questions that I had about those CO2 measurements.

More than welcome, Rhoda. Always more to learn, for all of us, myself included. That’s why I hang out here at WUWT …

Thanks once again, Willis, and Anthony too. I had thought, from time to time, about the CO2 readings from the Moana Loa observatory in my usual sceptical but unstructured way – you have very neatly enunciated my doubts and laid them to rest. It is good to have you and WUWT as a source of stuff one can trust, unlike so much ‘out there’ that is contaminated by vested interests.
OT, but Leo Hickman of The Guardian seems to regard anyone who attended the recent Chicago conference as tainted by association with ‘the lunatic fringe’ (his term, not mine) which denies the link between smoking tobacco and cancer, HIV and AIDS, etc.
I thought The Guardian had a new policy of playing nice with sceptics who are rational and polite, but I am unsurprised that the same newspaper carries no word of the ‘peer reveiwed and published’ (which they claim is their criteria for publishing) the paper debunking the alarmist nonsense about Tuvalu being in danger of being swamped by rising oceans.

anna v

Well, Willis,
would you accept the same reasoning for temperature measurements?
I.e. go to the top of a mountain at night and call that the global temperature?
I think that there is no meaning in global CO2 as there is no meaning in global temperature.
You quote:

The answer lies in the fact that the volcanic gasses are very rich in CO2. At night, they are trapped in a thin layer near the ground by a temperature inversion.
To detect the difference between volcanic and background CO2, the measurements are taken simultaneously from tall towers and from near the ground, at intervals throughout the night. Background CO2 levels will be around 380 ppmv (these days), will be steady, and will be identical at the top and bottom of the towers. Volcanic gasses, on the other hand, will be well above 380 ppmv, will be variable, and will be greater near the ground than at the top of the towers.

!!!!
And what prevents run of the mill CO2 molecules to generally to lie low?
Does each molecule carry a passport that says: I am from the volcano, I am from the top atmosphere?
Think of the oil spill. Would you defend measuring the chemistry of clear water next to the oil spill ? And we are talking of a gas that is supposed to be a good mixer?

dr.bill

John Finn: June 5, 2010 at 1:30 am
This will make an excellent link. Too often the ‘sceptic’ side gets distracted by muddled arguments about CO2 concentrations. The Beck measurements come up repeatedly. We need to accept that CO2 levels are increasing and that fossil fuel burning is almost certainly responsible for most of those increases.

That last sentence is a non sequitur, John.
/dr.bill

Tony

Good summary, Willis.
However, if this single data series from a single evolving methodology is all that is underpinning the CO2/Climate change hypothesis … then it certainly cannot support the weight of AGW theorising and speculation, let alone the Carbon Tax concept.
The Mauna Loa graph is after all, an ‘average’ struck from incredibly noisy datapoints that have huge variations. And, the parallel with the problem of trying to establish an ‘average’ global temperature series, is striking.
And so, I have concerns about the processes, and the history of the processes.
a) Re the various changes and ‘improvements’ that have been made (such as changing the material of the pressure vessels, the cleaning of the cell windows, etc.,) and whether retrospective reanalyses/corrections and restatement of the time-graph were made. Is there a ‘history of the history’ so to speak?
b) Has the statistical methodology been published?
c) Has the record of all the raw data been made available, and has anyone done a completely independent analysis?
d) You mentioned the idea that only the night-time samples are used because that air will be downwelling. But, does that not mean that this air was yesterday’s upwelling? And given the local wind-vector data, could a proportion of the downwelling sample have emanated from local population-centres (… that have grown over time)
e) For example, in the case of a very low average airspeed, the site itself seems to have grown substantially since the ‘fifties, with huge amounts of concrete, generators, airconditioners, road traffic, cooking, permanent staff (all CO2 producers?). Has there been an attempt at a correlation with a graph of the history of local CO2 emissions?
Such a claimed instrumental sensitivity ought to show such growth in an analysis of the daytime data record. Does it?
f) The seasonal variations that are claimed to be observed in the data history, is remarkable, and is ascribed to photosynthesis. Do these ‘waves’ in terms of shape and rates of change, correspond with the actual seasonal photosysthesis cycle of northern hemisphere land plants. At what latitude? Or, is the data showing only the effect of oceanic photosynthesis? Or dare I say it, only the local pacific ocean insolation and surface temperature changes?
Then, there is the Beck data. As you say, these records show CO2 concentrations on a local, low-altitude basis. They were made at a time when the industrial revolution was in full swing. I haven’t checked, but I vaguely remember that some of these series spanned WWI, where Anthropic CO2 emissions must have peaked dramatically, and slumped just as dramatically in 1919/20 . Does this show-up?
But more seriously, if an ‘average’ can be teased out of the fuzz of the actual Mauna Loa data, why can’t it be teased out of the presumably equally fuzzy Beck data using the SAME statistical techniques ?
I know that this raises a possibly silly thought, but as the increase in background CO2
is claimed to affect the climate, surely a local increase in CO2 on a local level ought to affect local weather? By that I mean that as climate maps to weather in terms of area and time, as measured by average temperature and influenced by average CO2 concentrations , then why cannot local average temperature records and local average CO2 concetrations be used to study the linkage. After all, whilst the data would be very ‘noisy’.. the same statistical techniques used by Scripps for CO2 and Climatologists for temperature, ought to yield comparable results.
A related question is the comparison of the Scripps CO2 measurement technique versus the earlier chemical technique, in terms of fundamental accuracy and resolution . Assuming that the two techniques can be correlated … it would be obvious to have seen the two techniques being used together, and results co-recorded. As I have not heard of chemical records from Mauna Loa, I assume they are not. Could you or any readers comment?
This raises a further question. I understand that over the past decade or so, several instances of alternative methods of measuring atmospheric CO2 have been developed. What has happened to these instruments? Do they work? I’d have thought that such systems would have been trialled at the Mauna Loa site? Why not? Can anybody shed light on this mystery?

Dear Willis,
I agree, the near ground data listed in my first paper do not reflect background data. Meanwhile I have found additional data which reflect CO2 background at that times. ( e.g. 1890 measured on islands at Baltic Sea or 1935 measured as a vertical profile over Helsinki)
Near ground concentrations are connected to the CO2 background (or MBL) over the vertical profiles. (please see our latest paper on http://www.realCO2.de: http://www.biokurs.de/treibhaus/CO2_versus_windspeed-review-1-FM.pdf). We can calculate annual background averages from near ground data.
You will find a graph of historical CO2 background based on that methods and updated historical station list on http://www.realCO2.de (http://www.biomind.de/realCO2/stations.htm.)
I have also prepared a new paper on the reconstruction of the CO2 background which is in peer review.
best regards
Ernst Beck

Geoff Sherrington

Willis,
(1) Has the 27m high tower been at ML from the start ca. 1973?
(2) What is the relationship between the concentrations of CO2 at ML, some 3,400m or more asl, and the CO2 concentrations where the greenhouse physics are invoked? It was my impression that terrain hugging CO2 at variable but often higher concentrations mattered most to global models of IR absorption/emission.
(3) Re methane, Tom Quirk has provided an official graph from Cape Grim at the N-W tip of Tasminia, which is mostly exposed to west winds that have crossed large ocean distances.
http://www.quadrant.org.au/img/content/May%202010/Quirk%203.jpg
The Cape Grim graph seems to sit somewhere between Barrow and ML and does not give the impression often mentioned of methane as a “globally well-mixed gas”. The annual wiggles at Cape Grim peak in the NH Autumn, but it seems improbable that their consistency is compatible with travel half way round the globe and over the Equator barrier. Yet people have described the shape of the Cape Grim methane curve as partly from plugging leaks in Russian gas pipelines (the plateau part) and partly methane release from melting marshland such as Arctic tundra. The appearance of the fine structure suggests none of these, as does the lack of plateaux at barrow and ML . It seems to be more local. See e.g. Karl, D M, Beversdorf, L., Bjorkman, K M, Church, M J, Martinez, A., and DeLong, E F. (2008) Aerobic production of methane in the sea. Nature Geoscience Vol. 1. July 2008, 473 – 478 (with HT to Steve Short).
If events local to the stations barrow, ML and CG, to which we can add the South Pole, are dominant, then it opens up scope for discussion of mechanisms, for CO2 as well as methane.

Thank you Willis for your excellent posts here on WUWT.
CO2 is also sampled in Vestmannaeyjar (Westman Islands) which are just south of the volcano Eyjafjallajökull. Eyjafjallajökull actually means:
Eyja = Islands (here the reference is Vestmanna-eyjar)
fjalla = mountains
jökull = glacier
So Eyjafjallajökull actually means “the glacier on the the mountains near the islands”.
Well, Vestmannaeyjar is also a volcano which erupted in the year 1973
http://www.nat.is/travelguideeng/volc_westman_islands.htm
NOAA: Monthly atmospheric CO2 record from Storhofdi, Vestmannaeyjar, Iceland:
http://cdiac.ornl.gov/trends/co2/cmdl-flask/ice.html
And some fun to you all from us here in the north:

Regards
Ágúst

Allen63

Nice description of the siting and the nominal advantages of the site.
I remain skeptical of ice core CO2 level reconstructions for multiple reasons.
I remain very skeptical that global CO2 increases imperil the Earth. I remain skeptical that humans cause the major increase. I doubt that the human contribution will continue to accelerate (assuming it is significant) simply due to economically driven (not artificially by cap & trade economics) changes in energy sources over the next century.

Richard S Courtney

Willis:
Thankyou for your clear explanation. I agree with much of it, but I have two objections.
Firstly, you say;
“As you might imagine from Fig. 2, the CO2 measurements are taken only at night. Thus, they are measuring descending air that is coming from thousands of feet aloft. This air has traveled across half of the Pacific Ocean, so it is far from any man-made CO2 sources. And as a result, it is very representative of the global background CO2 levels. That’s why Keeling chose the site.”
But the assertion of being “very representative of the global background CO2 levels” is denied by your own explanation.
CO2 is released by the Mauna Loa and the adjacent Kilauea volcanoes. According to your Fig. 2, this volcanic CO2 is
(a) driven aloft by the sea breeze by day, and
(b) driven back down by the land breeze at night.
Hence, it is a gross and improbable assumption that these volcanic emissions do not significantly affect the measurement results because “the CO2 measurements are taken only at night”. And the assumption is especially implausible when there is a slight wind in the direction from Kilauea towards Mauna Loa.
You attempt to overcome this objection by saying:
“To detect the difference between volcanic and background CO2, the measurements are taken simultaneously from tall towers and from near the ground, at intervals throughout the night. Background CO2 levels will be around 380 ppmv (these days), will be steady, and will be identical at the top and bottom of the towers. Volcanic gasses, on the other hand, will be well above 380 ppmv, will be variable, and will be greater near the ground than at the top of the towers.”
Sorry, but I do not buy that. Indeed, false confidence is provided by the comparison of the measurements of the sampled air and the measurements obtained at the towers. The air coming down at night contains CO2 carried aloft during the previous day, but this CO2 is diluted by its spatial spread over the time of its rise and fall. No such dilution can occur to the air at the bottom of the towers. Hence, I disagree with you when you say:
“This allows the scientists to distinguish reliably between volcanic and background CO2 levels.”
“Reliably” ?! No chance!
Secondly, you say of Beck’s data:
“I think that the Beck data is accurate, but that it is not measuring the background CO2.”
Perhaps, but I assert that the “background” level of CO2 is an irrelevance for three reasons.
The first of these three reasons is theoretical but the other two are practical.
Beck’s data indicates that the “background” level of CO2 does not exist anywhere:
i.e. the “background” level is mythical.
Indeed, this mythical nature of the “background” level it is why Keeling searched for a place where he may be able to discern this “background” level (and he chose Mauna Loa).
But the fact that the “background” level is mythical has practical importance.
The sequestration rates of CO2 are dependent on partial pressure. High local atmospheric concentrations induce high local sequestration. And consideration of seasonal variations in atmospheric CO2 at a variety of locations indicates that most locally released CO2 (from any source, natural or anthropogenic) is sequestered locally
(ref. Rorsch A, Courtney RS & Thoenes D, ‘The Interaction of Climate Change and the Carbon Dioxide Cycle’ E&E v16no2 (2005) ).
So, the mythical “background” concentration of atmospheric CO2 concentration has no relevance to flows of CO2 in and out of the atmosphere at any location.
Then, the radiative greenhouse effect of CO2 has a logarithmic relation to atmospheric CO2 concentration. And this is true at every location.
So, using the mythical “background” concentration of atmospheric CO2 concentration provides incorrect estimation of global radiative forcing from atmospheric CO2.
Please note that I present these disagreements with your article in a sense of scientific debate, and I respect your work.
Richard

Joel Heinrich

Somehow You guys really must despise the WMO, right? There are quite a lot of CO2 measurement stations worldwide not near a volcano all showing the same. Here is a map of the locations:
http://gaw.kishou.go.jp/wdcgg/products/summary/sum34/09_map_co2.pdf
You can get the data for all locations at the site:
http://gaw.kishou.go.jp/wdcgg/wdcgg.html
REPLY: Somehow you must really despise reading an article’s title and content for full comprehension, right? It is about the Mauna Loa observatory, on a volcano, in Hawaii. Not the ROW per se. Thanks for the links but sheesh, what a leap to bass ackwards conclusions. – A

RobJM

While the CO2 is going up, the cause can not be humans.
Atmospheric CO2 is only a small proportion (1/5oth) of the CO2 in the system, 98% is in the oceans.
Because CO2 is rapidly exchanged with the oceans (10% per year)due to precipitation stripping CO2 from the atmosphere, the atmospheric CO2 moves quickly toward equilibrium with the rest of the system.
Net result is 98% of the CO2 we emit is absorb into the oceans within the space of a couple of decades and the fossil fuel available to us is no where near enough to double the CO2 in the entire system.
The cause of the CO2 increase is increasing ocean temp,(increased degassing or decreased absorption) with humans only contributing about 5% of the increase.
This is why the IPCC lies about the residence time of CO2 in the atmosphere and claims its thousands of years, if the residence time is short all the CO2 will be absorbed by the oceans.

wayne

Willis, you should have included some different aspects.
For those of you that like to get a wide spectrum of view you should listen to a long time scientist, Dr. Freeman Dyson, whether he is exactly right or wrong. I tend to agree with a few of his views and question others.
To him co2 is totally vegetation ruled and as Willis’s 3d of co2 distribution over the latitude bands, this curve also closely fits the area of plant life if you take it one latitude band at a time. The nort hemispere has twice the land area. Look again at the 3d chart with vegetation in mind.
Freeman Dyson on Global Warming — Bogus Climate Models

2 parts.

Joel Heinrich

Here’s a picture comparing Mauna Loa to two German stations at the Black Forest (Schauinsland 1200m asl) and the Alps (Zugspitze 2962m asl):

Daniel H

Thanks for the excellent explanation of the Mauna Loa CO2 measurement process. It made sense to me except for the claim you made in point one where you state:

As you might imagine from Fig. 2, the CO2 measurements are taken only at night. Thus, they are measuring descending air that is coming from thousands of feet aloft.

The claim is directly contradicted in point number two, when you quote the measurement process that is described on the CDIAC web site:

Air samples at Mauna Loa are collected continuously from air intakes at the top of four 7-m towers and one 27-m tower. Four air samples are collected each hour for the purpose of determining the CO2 concentration.

This indicates that CO2 measurements are taken continuously and are not limited only to night time observation hours as you claimed. This is further supported by the link you provided to NOAA’s ESRL web page, How we measure background CO2 levels on Mauna Loa, which states the following under the sub-section, Data selection for background air:

No data are thrown away. Hourly means are calculated wherever possible, and how we use that data is indicated by the selection flags. Raw data are the voltages recorded for the air measurements as well as for the reference gas mixtures used for calibration and for the target gas.
On average over the entire record there are 13.6 retained hours per day with background CO2 mole fractions. The distribution is wide, as shown in Figure 3. Only those days with more than one remaining background hour have been plotted. There were zero days with 24 hours of background data after we introduced the target gas strategy, reducing the maximum number of background hours per day for almost all days to 23. Before we used the target gas we used 2 sets of reference gas mixtures, called working standards and station standards, as described in the references below. The number of days with 0 or 1 background hour comprises 6.5% of the total.

I’m hoping you can provide clarification on this issue.
On a completely different note, figure 4 is remarkable because it shows that atmospheric methane concentrations have recently begun to level off. Are there any plausible explanations that account for this interesting trend in CH4?

Telboy

Well said, Rhoda R – I fully agree.

Richard S Courtney

John Finn:
At June 5, 2010 at 1:30 am you assert:
“We need to accept that CO2 levels are increasing and that fossil fuel burning is almost certainly responsible for most of those increases.”
No!!
Please note how trivial the anthropogenic emission is to the total CO2 flowing around the carbon cycle.
According to NASA estimates, the carbon in the air is less than 2% of the carbon flowing between parts of the carbon cycle. And the recent increase to the carbon in the atmosphere is less than a third of that less than 2%.
And NASA provides an estimate that the carbon in the ground as fossil fuels is 5,000 GtC and humans are transferring it to the carbon cycle at a rate of ~7 GtC per year.
In other words, the annual flow of carbon into the atmosphere from the burning of fossil fuels is less than 0.02% of the carbon flowing around the carbon cycle.
It is not obvious that so small an addition to the carbon cycle is certain to disrupt the system because no other activity in nature is so constant that it only varies by less than +/- 0.02% per year.
In one of our papers
(ref. Rorsch A, Courtney RS & Thoenes D, ‘The Interaction of Climate Change and the Carbon Dioxide Cycle’ E&E v16no2 (2005) )
we considered the most important processes in the carbon cycle to be:
SHORT-TERM PROCESSES
1. Consumption of CO2 by photosynthesis that takes place in green plants on land. CO2 from the air and water from the soil are coupled to form carbohydrates. Oxygen is liberated. This process takes place mostly in spring and summer. A rough distinction can be made:
1a. The formation of leaves that are short lived (less than a year).
1b. The formation of tree branches and trunks, that are long lived (decades).
2. Production of CO2 by the metabolism of animals, and by the decomposition of vegetable matter by micro-organisms including those in the intestines of animals, whereby oxygen is consumed and water and CO2 (and some carbon monoxide and methane that will eventually be oxidised to CO2) are liberated. Again distinctions can be made:
2a. The decomposition of leaves, that takes place in autumn and continues well into the next winter, spring and summer.
2b. The decomposition of branches, trunks, etc. that typically has a delay of some decades after their formation.
2c. The metabolism of animals that goes on throughout the year.
3. Consumption of CO2 by absorption in cold ocean waters. Part of this is consumed by marine vegetation through photosynthesis.
4. Production of CO2 by desorption from warm ocean waters. Part of this may be the result of decomposition of organic debris.
5. Circulation of ocean waters from warm to cold zones, and vice versa, thus promoting processes 3 and 4.
LONGER-TERM PROCESSES
6. Formation of peat from dead leaves and branches (eventually leading to lignite and coal).
7. Erosion of silicate rocks, whereby carbonates are formed and silica is liberated.
8. Precipitation of calcium carbonate in the ocean, that sinks to the bottom, together with formation of corals and shells.
NATURAL PROCESSES THAT ADD CO2 TO THE SYSTEM
9. Production of CO2 from volcanoes (by eruption and gas leakage).
10. Natural forest fires, coal seam fires and peat fires.
ANTHROPOGENIC PROCESSES THAT ADD CO2 TO THE SYSTEM
11. Production of CO2 by burning of vegetation (“biomass”).
12. Production of CO2 by burning of fossil fuels (and by lime kilns).
Several of these processes are rate dependant and several of them interact.
At higher air temperatures, the rates of processes 1, 2, 4 and 5 will increase and the rate of process 3 will decrease. Process 1 is strongly dependent on temperature, so its rate will vary strongly (maybe by a factor of 10) throughout the changing seasons.
The rates of processes 1, 3 and 4 are dependent on the CO2 concentration in the atmosphere. The rates of processes 1 and 3 will increase with higher CO2 concentration, but the rate of process 4 will decrease.
The rate of process 1 has a complicated dependence on the atmospheric CO2 concentration. At higher concentrations at first there will be an increase that will probably be less than linear (with an “order” <1). But after some time, when more vegetation (more biomass) has been formed, the capacity for photosynthesis will have increased, resulting in a progressive increase of the consumption rate.
Processes 1 to 5 are obviously coupled by mass balances.
Our paper assessed the steady-state situation to be an oversimplification because there are two factors that will never be “steady”:
I. The removal of CO2 from the system, or its addition to the system.
II. External factors that are not constant and may influence the process rates, such as varying solar activity.
Modeling this system is a difficult because so little is known concerning the rate equations. However, some things can be stated from the empirical data.
At present the yearly increase of the anthropogenic emissions is approximately 0.1 GtC/year. The natural fluctuation of the excess consumption (i.e. consumption processes 1 and 3 minus production processes 2 and 4) is at least 6 ppmv (which corresponds to 12 GtC) in 4 months. This is more than 100 times the yearly increase of human production, which strongly suggests that the dynamics of the natural processes here listed 1-5 can cope easily with the human production of CO2.
A serious disruption of the system may be expected when the rate of increase of the anthropogenic emissions becomes larger than the natural variations of CO2. But the above data indicates this is not possible.
The accumulation rate of CO2 in the atmosphere (1.5 ppmv/year which corresponds to 3 GtC/year) is equal to almost half the human emission (6.5 GtC/year). However, this does not mean that half the human emission accumulates in the atmosphere, as is often stated. There are several other and much larger CO2 flows in and out of the atmosphere. The total CO2 flow into the atmosphere is at least 156.5 GtC/year with 150 GtC/year of this being from natural origin and 6.5 GtC/year from human origin. So, on the average, 3/156.5 = 2% of all emissions accumulate.
The above qualitative considerations suggest the carbon cycle cannot be very sensitive to relatively small disturbances such as the present anthropogenic emissions of CO2. However, the system could be quite sensitive to temperature. So, our paper considered how the carbon cycle would be disturbed if – for some reason – the temperature of the atmosphere were to rise, as it almost certainly did between 1880 and 1940 (there was an estimated average rise of 0.5 °C in average surface temperature.
Please note that the figures I use above are very conservative estimates that tend to exaggerate any effect of the anthropogenic emission.
Our paper then used atribution studies to model the system response. Those attribution studies used three different basic models to emulate the causes of the rise of CO2 concentration in the atmosphere in the twentieth century. They each assumed
(a) a significant effect of the anthropogenic emission
and
(b) no discernible effect of the anthropogenic emission.
Thus we assessed six models.
These numerical exercises are a caution to estimates of future changes to the atmospheric CO2 concentration. The three basic models used in these exercises each emulate different physical processes and each agrees with the observed recent rise of atmospheric CO2 concentration. They each demonstrate that the observed recent rise of atmospheric CO2 concentration may be solely a consequence of the anthropogenic emission or may be solely a result of, for example, desorption from the oceans induced by the temperature rise that preceded it. Furthermore, extrapolation using these models gives very different predictions of future atmospheric CO2 concentration whatever the cause of the recent rise in atmospheric CO2 concentration.
Each of the models in our paper matches the available empirical data without use of any ‘fiddle-factor’ such as the ‘5-year smoothing’ the UN Intergovernmental Panel on Climate Change (IPCC) uses to get its model to agree with the empirical data. Please note this:
the ‘budget’ model uses unjustifiable smoothing of the empirical data to get the model to fit the data, but each of our models fits the empirical data that is not adjusted in any way.
So, if one of the six models of our paper is adopted then there is a 5:1 probability that the choice is wrong. And other models are probably also possible. And the six models each give a different indication of future atmospheric CO2 concentration for the same future anthropogenic emission of carbon dioxide.
Data that fits all the possible causes is not evidence for the true cause.
Data that only fits the true cause would be evidence of the true cause.
But the above findings demonstrate that there is no data that only fits either an anthropogenic or a natural cause of the recent rise in atmospheric CO2 concentration. Hence, the only factual statements that can be made on the true cause of the recent rise in atmospheric CO2 concentration are
(a) the recent rise in atmospheric CO2 concentration may have an anthropogenic cause, or a natural cause, or some combination of anthropogenic and natural causes,
but
(b) there is no evidence that the recent rise in atmospheric CO2 concentration has a mostly anthropogenic cause or a mostly natural cause.
Hence, using the available data it cannot be known what if any effect altering the anthropogenic emission of CO2 will have on the future atmospheric CO2 concentration. This finding agrees with the statement in Chapter 2 from Working Group 3 in the IPCC’s Third Assessment Report (2001) that says; “no systematic analysis has published on the relationship between mitigation and baseline scenarios”.
Richard

Slioch

Willis
I have at times been critical of some aspects of your articles, but the above is well written and informative and should put to rest any lingering doubts about increases in atmospheric CO2 levels amongst WUWT readers.
I would merely add that the annual “wriggle” in CO2 levels picked up in the Mauna Loa data (caused by annual dying and regrowth of northern hemisphere temperate vegetation) is also strongly indicative that the MLO data is a) globally representative and b) not distorted by local CO2 emissions.
pat says:
June 5, 2010 at 12:16 am
says, “I suspect that much of the CO2 we now measure is because of oceanic out gassing, caused by global warmth. ”
There has been more than enough CO2 emitted from human burning of fossil fuels to account for all the increase in atmospheric CO2 in recent centuries.
The figures for the atmosphere from 1850-2000 are as follows:
1. Total human caused emissions of CO2: = 1620 billion tons CO2
2. Increase in atmospheric CO2: 640 billion tons CO2
Thus, the amount of CO2 humans have added to the atmosphere greatly exceeds the observed increase in CO2 in the atmosphere, so the human contribution is more than able to account for the entire increase. Most of the CO2 emitted by humans in that time, about one trillion tons (1620-640 billion tons), has been absorbed into the oceans and terrestrial biosphere. In other words, the oceans, far from “outgassing” have been acting as a massive sink for CO2.
If you want to check the figures go to the Carbon Dioxide Information Analysis Centre: (I’ve converted their figures to ‘tons of CO2’ from ‘tons of C’)
http://cdiac.ornl.gov/faq.html#Q4

Joel Heinrich


How better to show that the fact that the site is located on a volcano isn’t important than to compare it with other locations not near a volcano? Part of the problem in the discussion about Mauna Loa is that some people think that it is the only CO2 measuring site. Thanks, but I think I understood the intention of the post.
Here is the link to the picture again:
http://i45.tinypic.com/1scwtd.jpg
source: GAW letter from DWD november 2003

Peter Miller

Below is probably the most comprehensive document I have yet seen explaining in great detail why rising carbon dioxide levels are either beneficial or only have a very minor impact on global temperatures.
It is one of the best argued and illustrated trashings of the bad science of IPCC, Mann, Giss etc.
Climatic variations are natural cycles, that is what it is all about – as any good geologist will tell you – not the conclusions of bad science, created by billions of mispent tax dollars.
http://www.google.es/images?client=firefox-a&rls=org.mozilla:en-GB:official&channel=s&hl=es&q=holocene+temperatures&um=1&ie=UTF-8&source=univ&ei=4CAKTN6hHOeW4gbt8riTAQ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CDwQsAQwAw

Tony

Willis,
The whole basis of Scripps’s long-term experiment seems a bit odd to me, and so here is a question for the historians, the answer to which should dispose of a number of open questions.
When Scripps started his project to look at ‘background CO2’ . I wonder what primary justification was used in his funding proposal. I suspect that the concept of an ‘average global CO2 level’ given the light of the knowledge and the data of the time, would have (… and still probably does … ) seem faintly pointless. But as a secondary justification it would make sense as a cover for a more stratgegic purpose.
In the early days of the cold war, it would seem strategically important to find a method of detecting nuclear tests, and finding a way of estimating the power and hence the progress of the ‘opposition’. One way would be to look at the charateristic carbon isotope signature in the atmospheric CO2. What better place than Mauna Loa, with no other local sources of atmospheric carbon such as methane? Pacific tests were coming up, which could calibrate the process. The presence of a local natural CO2 source could be calibragfted-out as we see, but at heart it was was the absolute incidence of the isotope itself that mattered.
And when we look at the programme itself, it relies primarily on a relatively expensive logistical chain of pressure flasks going to and from this, and other sites. This would easily permit a second more sensitive analysis for the isotope, which may not have been practical on-site at the time. And, it also makes a kind of sense that a co-location of alternative direct methods of measuring CO2 concentrations, is not apparently encouraged.
So, in Mauna Loa, and the Scripps system, are we looking at an artefact of the cold war? A quick search through the archives might give us an answer.

Bernd Felsche

Willis, Ernst and Richard;
Thanks to you all for your thoughts and comments. Especially Willis for taking the time to explain the methodology and assumptions put into measuring CO2 at Mauna Loa.
I agree with Richard that it is folly to look for a background level of CO2. I cannot figure out the rationale behind such an assumption. Especially given the enormous variation in measured CO2 levels w.r.t. location, (altitude,) season, time of day and year; as documented by Ernst. It’s like trying to look for a global, average temperature. It’s arithmetically valid but physical nonsense.
Radiative heat transfer is goverened by temperature; by a 4th-power relationship to any factors involved cannot be simply averaged to determine the nett heat flux. It has to be an integral over the surface, through the depth of the atmosphere, several metres of surface, with the temperature at each component and its radiance in space; at a particular time, in order to give a correct result. And that is never going to be possible.
The CO2 remaining in the atmosphere after photosynthesis is determined largely by photosynthesis; governed by insolation, water and trace nutrients – either on land or in the oceans. All other things being equal; a reduction in insolation over a long period will reduce the amount of (CO2 absorbed by) photosynthesis and leave more in the air, increasing the concentration.
There is an opposite effect, with reduced insolation, in the cooling of oceans which increases the solubility of CO2 inthe water and decreases atmospheric levels. And as the concentration of CO2 in the air increases, more CO2 also dissolves into the oceans. A negative feedback.
Which brings me to ask:
What were the levels of CO2 in the air and oceans during ice ages?
Maybe those are the “background” levels for a nearly-dead planet.

Stephen Wilde

A nice explanation as to why criticism of the Mauna Loa record is not likely to be fruitful.
The clincher for me long ago was the similarity with the Barrow Alaska record.
As always I like simplicity so I look for the largest influence and see whether that might be enough on it’s own to explain observations.
That leads to the oceans (yet again) and more particularly the rate of oceanic CO2 uptake or release. Nothing else comes close.
Now we clearly have a 500/1000 year climate cycling from Mediaeval Warm Period through Little Ice Age to the recent warming and it seems that goes back quite some time into history. So for a trend of CO2 to be consistent for periods up to 500 years at a time is perfectly consistent both with observations and past climate records.
The oceans are clearly involved in those 500/1000 year cycles and history tells us that the jets and the ITCZ moved poleward or equatorward over similar time scales.
Thus we have a regular change on those same time scales in the global albedo resulting from those cloud bands shifting latitudinally and so a regular change in the quantity of insolation to the oceans.
The oceanic rates of CO2 absorption or release will clearly vary in tune with those insolation changes and likely also in tune with any underlying oceanic variability in terms of surface temperature changes that may be induced by small temperature variations along the horizontal path of the thermohaline circulation.
I fail to see why that cannot be a wholly adequate explanation for the observed CO2 variations.
The isotopic analysis identifying so called ‘human’ and ‘natural’ CO2 would be a mere distraction in view of the sheer scale of the oceanic effect and the indifference of the oceans to the source of the CO2 that it is either able or unable to absorb at any given time.
Note that the idea of oceanic outgassing is misleading. What matters more is the changing rate at which oceans can absorb CO2. That will be heavily insolation and sea surface temperature related. Sometimes the oceans will absorb CO2 faster than it is created and sometimes more slowly than it is created and it appears that the 500/1000 year cycling is paramount in timescales relevant to us. It is questionable whether the ice core and other proxy evidence for historical CO2 levels is sufficiently precise to reveal that relatively short term pattern.

Gail Combs

John Finn says:
June 5, 2010 at 1:30 am
This will make an excellent link. Too often the ‘sceptic’ side gets distracted by muddled arguments about CO2 concentrations. The Beck measurements come up repeatedly. We need to accept that CO2 levels are increasing and that fossil fuel burning is almost certainly responsible for most of those increases.
_____________________________________________________________________
You are forgetting that CO2 dissolves better in cool water and out gases when water warms (think of a can of soda) If the sea temperatures have risen since the Little Ice Age (roughly 1300 to 1850), then we can expect the amount of CO2 to rise in response. Remember 70% of the earth’s surface is water.
Plants respond to warmer temperatures and higher CO2 levels by taking CO2 out of the atmosphere. Insects respond by becoming more active (remember the big CO2/methane emitters – termites) Also there is a temperature/soil response. http://wattsupwiththat.com/2010/04/28/new-ground-truth-microbiotic-negative-feedback/
To say that fossil fuel burning is almost certainly responsible for most of those increases. Is very simplistic given the hydro/biosphere is a complex system.

RalphieGM

Of course, Keeling could have picked a sampling site where this volcano was not an issue at all. That would have been nice. “No apologies data” is the best data.

Joe Lalonde

Excellent presentation Willis!
I wish to thank you for the incredible researching you do for WUWT.
Gives more to think about the CO2 theory.
Seems the CO2 theory and temperature relationship are moving further apart though.

Gail Combs

Ernst Beck says:
June 5, 2010 at 2:44 am
I have also prepared a new paper on the reconstruction of the CO2 background which is in peer review.
__________________________________________________________________________
I want to thank you for your work Mr. Beck. I especially appreciate the error bars shown on your historic CO2 graph and your willingness to go back, look at your work and refine it.
I look forward to reading your peer reviewed paper.

C. Bruce Richardson Jr.

Very interesting. Exactly what I needed to know. Thanks.

Bill Yarber

A previous poster on this site suggested quite a while ago that and experiment should be conducted to verify that the CO2 concentrations found in ice core data is indeed representative of atmospheric concentrations at that time. Has anyone actually done such an experiment (freeze water in the presence of a know concentration of CO2, store it at freezing conditions and then test portions over various time periods) to verify that:
1) the concentrations actually match
And
2) there is no degradation in CO2 concentrations over time.
This is far more important than whether CO2 measurement at Mona Loa are precisely accurate. Even if there is a bias due to contamination from the volcanoes emissions, they should be a relative consistent error and thus are irrelevant.
Bill

Willis,
Thank you for writing this, it’s been a long time since there was some discussion about the dealing with CO2 vs. the volcano. Even then, it may have been buried in discussion about a data reporting/disk crash flap a couple years ago.
The best of those posts include quite a bit of dialog with Pieter Tans from MLO and is worth a review, see http://wattsupwiththat.com/2008/08/06/post-mortem-on-the-mauna-loa-co2-data-eruption/
In http://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.html#data_selection MLO refers to the diurnal effect due to land breeze/sea breeze (upslope/downslope) effects. During a 1974 bicycle tour from Palo Alto CA to Billings MT, I noticed similar effects well inland – uphill grinds often had a bit of a tail wind, downhill runs had a bit of a headwind. Currently, our mountain property develops a downslope draft at night that significant affects our campfire site. I.e. sit upwind, try to ignore the cold breeze on your neck.
In windier conditions, I suspect MLO samples air from something close to its altitude. At Mt Washington here in New Hampshire, the wind is almost dominates any diurnal effect and diurnal temperature difference is remarkably low, compare http://vortex.plymouth.edu/mwn24.gif with http://vortex.plymouth.edu/con24.gif . These make for a handy rule of thumb – I take the MWN temperature, add about 30°F and that gives me something close to the high temperature for the day at home. Since MWN doesn’t see much daily heating, I conclude it’s seeing little air that is in contact with the ground, and I expect MLO benefits from the same effect so some daytime samples are uncontaminated.