The Embarrassing Bomb-Test-Curve


The Embarrassing Bomb-Test-Curve

Why all the fuss about carbon? It only stays in the atmosphere for 10 years.

During the 1950s and 1960s, several nations performed atmospheric tests of nuclear weapons. The radiation effects of these tests produced large amounts of C14-carbon dioxide (14CO2) in the air. 14C is an isotope of carbon, the common isotope being 12C. When the bomb tests ceased in 1963, the atmospheric level of 14CO2 had been raised to about twice its previous natural value. This extra 14CO2 can be used as a tracer for tracking the movement of carbon through the natural world – the Carbon Cycle. This wonderfully serendipitous experiment would be hard to beat even if someone designed it.

Over the following half-century the amount of 14CO2 measured in the global atmosphere diminished in a text-book exponential manner as shown in the diagrams above.

14C is radioactive but this curve is not the radioactive decay curve. The half-life of radioactive 14C is 5,730 years , whereas the half-time of the bomb-test curve is only 10 years, i.e. after 10 years only half was left, after 20 years, one quarter was left, after 30 years, only one eighth and so on.

The half-time of CO2 in the atmosphere is of great interest to climate modellers. They assume that CO2 is removed from the atmosphere according to a theoretical curve called the “Bern Model” or a similar curve called the ISAM model. The blue line in the lower panel shows predicted atmospheric decay curve of 14CO2 according to the Bern Model. It is quite different to the observed curve.

The Bern Model utilises four different half-times and does not return to nearly zero after 60 years as does the bomb-test curve. According to the Bern Model it will take centuries for 14CO2 (and anthropogenic CO2) to be ultimately removed from the atmosphere. The modellers chose to adopt the more alarmist scenario despite the fact that it is “non-physical” (i.e. obviously wrong).

Admittedly it is complicated: CO2 reacts with water chemically and this slows down the rate at which it dissolves. Furthermore, while there is a fast interchange of gases between the atmosphere and the top 100 metres or so of the ocean called the “mixed layer” (~70 Gt per year), it is widely assumed that there is much less transport through the bottom of the mixed layer (~2 Gt per year, IPCC figures). The latter is the reason for the flattening out of the Bern Model curve at times longer than 60 years.

But despite these quibbles about the half-time and the shape of the curve, one incontrovertible fact remains:

In 50 years nearly all the bomb-test 14CO2 has disappeared!

Since the 14CO2 reaction rates, solubilities and diffusion times are very similar to those 12CO2, this implies that all the ordinary atmospheric CO2 in the atmosphere at the time of the bomb test has completely changed over.

Where has all the 14CO2 gone?

There are various possible CO2 reservoirs, e.g. the biosphere and the mixed layer, but the problem is that these are roughly same size as the atmosphere. A new equilibrium would be soon be reached wherein the bomb 14CO2 would be partitioned between the reservoirs in proportion to their capacity, so causing the bomb 14CO2 in the atmosphere to level off in a similar way to the Bern model curve.

Instead it tends to zero. That this happens implies that the bomb 14CO2 has either been transported to a reservoir that is much, much larger than the atmosphere or it has left the ocean-atmosphere system.

It is commonly accepted that approximately 38,000 Gt of CO2 are dissolved in the deep ocean, more than 100 times the amount generated by humans since the start of the industrial revolution. The deep ocean is larger than any other conceivable reservoir. Either the missing 14C is sequestered in the deep ocean or it has been removed altogether, perhaps as carbonate in the skeletal material of sea creatures.

WOCE – the World Ocean Circulation Experiment produced detailed maps of the major constituents of the oceans in the mid-1990s. The WOCE Atlas is on-line and it is certainly worth a look; oceanography at its very best. The Pacific Ocean maps and sections are the most detailed and complete.

One of the chemical signatures mapped by WOCE is delta 14C, the proportion of 14C above the background level. Here is a map of delta 14C in the Pacific Ocean at a depth of 200 metres:


and here is a longitudinal section of the top 1000m at 150 deg W (near the Hawaiian Islands, represented by the black bar):


All of the pink area (delta 14C positive) reflects bomb-test 14C. Using WOCE maps of total carbon it is possible to estimate how much of the bomb-contaminated atmosphere finished up in the Pacific Ocean after 30 years.

The answer is 30 Gt, only a tiny fraction of 700 Gt lost from the atmosphere in that time.

Evidently atmospheric carbon is being sequestered in the Pacific at the rate of about 1 Gt/year which fits the IPCC figure of 2Gt per year for the whole ocean. Wherever most of the bomb-test 14C has gone, it is not the Pacific Ocean.

What about the Southern Ocean? Because the Southern Ocean is so turbulent, it has a very deep mixed layer and, in theory, this should allow, atmospheric CO2 to mix down much deeper and then to flow northward along constant density surfaces (isopycnals) into the deep, temperate-zone ocean. However recent theoretical work (Sallee et al, Nature Geoscience, 2012) has shown that only 0.42 Gt per year can be sequestered in this way. Furthermore WOCE sections such as Section P16, shown above, do not support the idea that the Southern Ocean is the gateway for CO2 transport into the deep Pacific. Rather, these observations imply that the bomb-test 14C has moved slowly downwards and equator-wards from the north and south temperate zone mixed layers across the isopycnals.

What about the Indian and Atlantic Oceans?There appears to be no WOCE delta 14C data available for these oceans. After 20 years the WOCE people have not quite gotten around to working up the Indian and Atlantic 14C data for public display.

What is the problem? Bomb-test 14C is the best tracer available for tracking the circulation of the deep ocean, the stated aim of the World Ocean Circulation Experiment. Its absence from the WOCE data sets is very strange. Under normal circumstances it would be reasonable to assume that this is due to some sort of technical glitch or funding hiatus. However taken together with NASA’s obvious embarrassment with their remarkable OCO-2 satellite observations of atmospheric CO2 distribution discussed previously here and here, it implies a hidden agenda. At the time of writing no further OCO-2 maps have been published by NASA. Why are CO2 maps so embarrassing?

The Keeling Curve. Wikipedia: The Keeling Curve is a graph which plots the ongoing change in concentration of carbon dioxide in Earth’s atmosphere since 1958. It is based on continuous measurements taken at the Mauna Loa Observatory in Hawaii that began under the supervision of Charles David Keeling. Keeling’s measurements showed the first significant evidence of rapidly increasing carbon dioxide levels in the atmosphere. Many scientists credit Keeling’s graph with first bringing the world’s attention to the current increase of carbon dioxide in the atmosphere.

Graphs showing the remorseless increase of atmospheric CO2 are commonplace on the Web and in the media. Keeling’s Mauna Loa graph has been replicated many times at other monitoring sites throughout the world such as the Baseline Monitoring Station at Cape Grim in NW Tasmania. It is incontestable; the concentration of CO2 in the atmosphere has been steadily increasing since 1958.

What is contestable is the explanation given for this increase. It is commonly assumed that the increase is entirely due to human industrial activity and land-use changes. It is commonly assumed that the movement of CO2 through the oceans and the biosphere, the Carbon Cycle, is well understood and that the human contribution is both significant and harmful. The bomb-test curve shows these assumptions to be questionable. It shows that the Carbon Cycle is certainly not well understood and that atmospheric CO2 does not behave as we thought it did back in 1995 when the IPCC was set up. As more information comes to light, the assumptions on which “Climate Science” is based become ever more dubious.

Gösta Pettersson, Professor Emeritus of biochemistry at Lund University and an expert in reaction kinetics, estimates that less than half of the observed CO2 increase is man-made. Murry Salby suggests the figure is less than one-third. If half of the atmospheric CO2 (360 Gt) turns over every 10 years due to natural causes this is hardly surprising; the human contribution in ten years is around 90 Gt.

Pettersson has self-published a book on this, “Falkst Alarm”, which unfortunately is in Swedish. English versions of key chapters can be downloaded here (paper4 and paper5). A more formal description of the above argument can be found here: BombTestImplications

Climate change has become a billion dollar industry. Let’s not spoil a good thing for the sake of a single graph.

17 thoughts on “The Embarrassing Bomb-Test-Curve”

  1. John,

    Before you resort to conspiracy theories “implying a hidden agenda” and claiming that climate change has become a “billion dollar industry”, it’s worth reading a bit outside the standard contrarian blogs and peripheral literature. It’s also worth presenting information correctly to your readers. You start your piece showing Pettersson’s graphs, suggesting that these show C_14 concentrations, whereas they actually show Delta_C_14, which is significantly more complicated than a simple concentration – in fact, it is based on the difference (from 1) of the ratio of C_14/C_12 in a sample to C_14/C_12 in a standard (followed by “fractionation” adjustments) – this means it can actually go negative. If you look at the paper by Heather Graven
    you’ll see two things:

    1. Delta_C_14 was indeed negative prior to about 1955 and will be in the future due to fossil fuel emissions, and

    2. the reason for the sharper reduction of Delta_C_14 than we would expect from a simple mixing model is because of the dilution of C_14 by C_14-depleted fossil fuel emissions.

    It’s worth noting that the standard originally used for the definition of Delta_C_14 was 1890 wood – the date 1890 being chosen because it was growing prior to most fossil fuel emissions. So it was actually defined with an understanding that it can be affected by fossil-fuel emissions!

    You mention none of this in your article – if you had, you might have been able to educate the reader and not have had to resort to conspiracy theories.


    1. 1. I have never used the word “conspiracy” in any context on this blog. Researchers may be mistaken without being conspirators. The pages of any issue of Science or Nature reveal the vast extent of the climate change industry.

      2. The definition of delta 14C is not strictly a “concentration” because it can become negative as you rightly point out. However it is closely related to concentration, it is a concentration relative to a standard datum. I did not say this because the inclusion of footnotes, references and definitions in a popular article make it far less readable for the lay person. If a reader needs a proper definition they can always refer to Wikipedia.

      3. I had already read the paper by Heather Graven. Apart from her alarmist tone, she says very little more than did Hans Suess back in 1955.

      4. Evidently you have not read her paper yourself otherwise you would not have made the statement “the reason for the sharper reduction of Delta_C_14 than we would expect from a simple mixing model is because of the dilution of C_14 by C_14-depleted fossil fuel emissions”. At the end of the third paragraph Graven states “Atmospheric delta 14C was prescribed by observations until 2005″, i.e. the observed exponential decay is not a consequence of her model assumptions. If you can present a model which accounts for the observed exponential decay in terms of dilution by fossil fuels I would like to see it.

      5. Thank you for the observation about 1890’s wood. I had not realized that. It is worth noting that when the Suess curve is calculated for even older atmospheric carbon there is a good deal of variability due either to changes in the rate of 14C production by cosmic rays or changing dilution due to natural “old” carbon from other reservoirs such as the deep ocean.

  2. John, your reply to Euan omits the biosphere, the carbon content of which is much bigger than that of the atmosphere. The biosphere and the top ocean layer dwarf the atmosphere. And of course there is significant deep ocean transport of carbon as well (think of marine sediments, ocean currents, upwelling of rich waters etc).

    1. My model is simple so that people can better understand the argument. I will go into finer detail: according to Figure 3.1 of IPCC TAR and elsewhere the biosphere and upper ocean reservoirs are

      Soil 1500 Gt
      Plants 500 Gt
      Mixed Layer 670 Gt
      total 2670 Gt

      Atmosphere 730 Gt

      total 3400 Gt

      Hence, the bomb-test curve should tend to 730/3400 i.e. about 20 percent of its initial value. It does not. Deep ocean transport is supposed to be very small, about 2 Gt per year globally. This is the reason for the longest time constant of the Bern model.

      The bomb-test curve implies that
      (1) the atmosphere is in intimate contact with a reservoir much larger than biosphere plus mixed layer, and
      (2) the half-time of its interaction with this reservoir is about 10 years.

      The bomb-test curve is, in effect, the impulse response of the atmospheric carbon reservoir and shows quite clearly that extra carbon 14 in the atmosphere is rapidly removed. Anthropogenic carbon will be removed equally rapidly. The amount of anthropogenic carbon in the atmosphere at a given time is the production rate convoluted with this impulse response.

      My guess is that the bomb-test carbon finished up in the deep Atlantic. What a pity there is no WOCE data available with which to test this hypothesis.

      Note 1 Gt (Gigatonne) = 1 Pg (Petagram)

      1. The 2Gt transport to the deep ocean that you mention is the net transfer from flows of around 90Gt to and from the deep ocean. The shallow ocean is depleted of bomb test C14 constantly by these flows, so the equilibrium you describe (equal ppm of C14 in air, land sea) will not happen and atmospheric C14 will sink faster than the Bern model says – as is observed.

        1. The 2Gt transport to the deep ocean that you mention is the net transfer from flows of around 90Gt to and from the deep ocean.

          Not according to the IPCC.

          1. You quoted me: “The 2Gt transport to the deep ocean that you mention is the net transfer from flows of around 90Gt to and from the deep ocean.”

            and then said: “Not according to the IPCC.”

            What do you mean by that? It is quite clear that there are huge flows. This IPCC figure (from AR4) shows 101 GtC up and down (down is 90.2 + 11):

            Has IPCC opinion on this changed?

            1. You are right. I was using IPCC TAR (2001) figures and had not taken much trouble to keep up.
              I have been using

              and assumed that the ~90 Gt/yr in Fig 3a is interchanged solely between the atmosphere and the mixed layer with only 2 GT/yr going from the mixed layer into the deep ocean (Fig 3b and similar figures elsewhere).

              Your Figure 7.3 from IPCC AR4 (2007) shows a whopping 90 – 100 Gt going backward and forward. So yes, the IPCC did change its tune considerably between 2001 and 2007 and I was not aware of that. My interpretation of the bomb-test curve is completely in line with the the AR4 2007 report according to which the CO2 in the atmosphere is indeed in intimate contact with the very large (38,000 Gt) deep ocean reservoir so the exponential should trend to a value 730/38,000 times its original concentration, i.e. less than the observational error. The IPCC contributors should also be well aware of this so why are we still being told that the anthropogenic CO2 stays in the atmosphere for centuries? Why is the Bern model still in use? And where in the oceans did the bomb-test 14C finish up?

              Many thanks for your persistence and a good discussion.

  3. Climate religion is now jihad for Western liberal governments. It offers a crowd-mobilizing external threat without the political inconvenience of invasion of other countries. Theocracy is the most enduring form of governance. Why change now?

    1. Agreed, and in the process empirical science, the jewel in the crown of Western civilization, is trashed. The cash and the kudos go to rent-seeking charlatans while those who would speak truth to power are vilified.

  4. Hi John, about a year ago Roger Andrews and I thrashed the Bern model to death. The big anomaly is the 14C bomb test curve. In this post I show why that data CANNOT be used to constrain the kinetics of CO2 sequestration.

    Whats up with the bomb model

    Its not a popular finding for sceptics, and for example, this post was not cross posted on any of the bigger sceptic blogs and the myth survives. I am an isotope geochemist and more accustomed to working with such data than most.

    1. Hi Euan

      It was reading your post that got me thinking about this in the first place!

      I don’t agree with your argument for the following reason: In effect your Figure 6 depicts a two reservoir model, the reservoirs being the atmosphere and “the ocean”. As your Figure 5 diagram shows the ocean is not a single reservoir but itself comprises two reservoirs, surface water aka as “the mixed layer” and the deep ocean. The exchange rate between the mixed layer and the deep ocean is assumed to be very much smaller than that between the mixed layer and the atmosphere.

      For simplicity assume this to be zero and forget the deep ocean for the moment. We are back to a two reservoir model with just the atmosphere and the mixed layer. The atmosphere is perturbed by a single pulse of 14C. By le Chatelier’s Principle, the system will tend towards a new equilibrium in which the bomb-test 14C is distributed between the two reservoirs in proportion to their respective capacities of 730 Gt (atmosphere) and 680 Gt (mixed layer). Hence 730/(730+680) X (original concentration) will finish up in the atmosphere and 680 / (730+680) X (original concentration) will finish up in the mixed layer.

      But this is not what the bomb-test curve actually shows. It has decayed to nearly zero over 50 years implying that the second reservoir must be very much larger than the atmosphere and so very much larger than the mixed layer. If you now plug in the small but non-zero exchange rate of Figure 5 between the mixed layer and the deep ocean, your model is just the Bern model.

      Another thought experiment is this: what happened to the bomb-test 14C? Where did it all go?



  5. This is erudite, thorough and well researched, a necessarily detailed explanation.But for me as a lay person.It sensitively explains new technical details sufficient for genuine understanding.
    Lets hope there a members of the fourth estate who will make the effort[as partisans of critical examination] to read it and report.

  6. As a non-scientist, I could actually understand this. I’m in London, and this part of the world is having its worst summer in decades. The web is full of graphs showing this is only a temporary glitch, but put it this way, if their graphs were showing stock market trends instead of climate and I owned the stock, I’d be selling right now.

  7. Thanks John, for this great, because so wide ranging, explanation ! Such a very great pity for the world, your “What is the problem?” section, “Bomb-test 14C is the best tracer available for tracking the circulation of the deep ocean, the stated aim of the World Ocean Circulation Experiment. Its absence from the WOCE data sets is very strange . . . a hidden agenda” ! ! ! !

  8. Thanks, John,
    As a non-scientist who has difficulty knowing what an isotope is, I found I could follow the argument here with little trouble, and had my understanding of CO2 and ocean/atmospheric circulations extended, and my sceptic view of the Climate Change disgrace made more crystalline.

  9. The sad thing is, government condones, and promotes the multi-trillion dollar rip-off! The greatest threat to modern civilization we face today, is Government-induced “Climaphobia”! People are being extorted, through fear of natural processes. Hard to believe they are getting away with it. I suppose the overwhelming number of people who blindly accept the word of the paid shills, about the various “cures”, (all costing enormously unaffordable amounts of money), for the earth’s changing climate. Whether we throw all of our money, to the perpetrators of this scam, or not, our climate is going to change, just as it always has. It is our job, to adapt to any changes in our climate, not try to control it.

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