Is Carbon Dioxide Innocent of Global Warming?

The basic assumption of the importance of CO2 in global warming is overstated.  The models assuming that CO2 is the primary driver behind global warming manifestly do not match the observations.


oil and gas consultantsBy Peter F. Owen

Independent consultant in acquiring, processing and interpreting seismic data,

Some time ago I posed the question of why CO2 was the culprit for global warming, and was given the answer, by an academic in the Earth Science field, that it ‘absorbs, and re-transmits infra-red radiation (IRR) in all directions’. Although this statement is true, it is disingenuous from three aspects.

Firstly, CO2 concentration has a ‘net effect’ on IRR and the contribution of this ‘net effect’ is greater, when radiation is the sole mechanism of energy transfer from the Earth’s surface to the outer atmosphere. However, because transfer by convection, and by latent heat (of evaporation/cooling) occurs, the importance of IRR must be diminished. Observations from satellites indicate the monthly averages of radiation imbalance (difference between incoming and outgoing radiation) are poorly correlated with temperature (figure 14 in R. Spencer, 2010, ‘The Great Global Warming Blunder’). Around the mean point, the range of temperature, for a given quantity of radiation imbalance, is well over half the total range, implying that factors other than radiative transfer affect global temperatures.

Secondly, CO2 is not unique in having a ‘net effect’ on IRR; water vapour has the same property. In terms of atmospheric composition, it is a very variable component, but, on a summer day, on land, in mid-latitudes (temperature 300C, relative humidity 50%) there are typically over 50 molecules of it, for every CO2 molecule. Over the oceans, the proportion is much greater. This observation suggests water vapour has over 50 times the ‘net effect’ of carbon dioxide, all else being equal.

Thirdly, CO2 molecules only have a ‘net effect’ on a small fraction of the infra-red spectrum, rather less than one half of the fraction that is affected by water vapour. The implication is that, at present, the ‘net effect’ of CO2 is under one hundredth that of H2O. Furthermore, the radiation output from the earth is not confined to the IRR part of the spectrum. Some energy is lost in the visible part, both by reflection of incoming solar radiation (albedo), and re-emission from the earth itself; the earth does not appear as a black hole on satellite images.

From direct measurements of CO2 concentrations and global temperatures since 1960, the former has risen steadily whereas the latter has not. During the last ten to twelve years, global temperatures recorded in both surface measurements (HADCRUT) and satellites (various) have remained more or less constant (or even declined slightly), while the CO2 levels have continued their anthropogenic rise. A similar standstill in temperature occurred from the late 1940’s until the late 1970’s. Only for the approximate period 1977-2003 did a rise in global temperature coincide with the rise in measured CO2 concentration. It is difficult to reconcile these observations with the assertion that global temperature is highly sensitive to CO2 concentration. Because temperature is poorly correlated with radiative imbalance, above, it is much more plausible that CO2 concentration has minimal effect on temperature.

An approximate 65 year fluctuation in temperatures, independent of CO2 concentration goe some way to explaining the lack of short-term correlation. This happens to be approximately the period of the Pacific Decadal Oscillation; combined with the 11-year sunspot cycle, much of the measured temperature variation can be attributed to ‘natural causes’. Once one accepts this possibility, there is no reason that other, natural events may explain longer term temperature variations, such as the medieval warm period, the little ice age, the warming during the 20th century let alone the major Pleistocene ice ages, and inter-glacials (below). Most of these occurred long before the addition of anthropogenic CO2 to the atmosphere. In addition, in the short term, random events (volcanic eruptions, for example) add ‘noise’, or chaotic behaviour to the system.

To extend the timeframe of observations, tree ring widths have been used as a proxy for temperature during the historical period, as a basis for concluding that temperature changes are correlated with CO2 concentrations. Since plant growth depends on four independent variables – availability of water, air (including CO2), light intensity, and temperature – using tree ring width as a proxy for just one of these is scientifically unsound.

Over a longer time scale, the ice core data (400,000 years in the Vostok core, for example) show that temperature changes and CO2 concentrations have varied in step with one another, although at the beginning of warm episodes, the rise in CO2 levels never precedes the temperature rise. Two recent re-evaluations of the latest de-glaciation episode have claimed that this is not the case. One used a correlation technique to minimise the ‘background noise’ and their results showed peaks corresponding to lags of at least 200 years for CO2 behind temperature. The other attempted to recalibrate the ice depth vs. age, using the slightly suspect proposition that density transfer of ‘heavy nitrogen’ occurred in the firn layer, during the last warming period. Even accepting this, the lag at the two events where warming occurred was over 200 years, but was reduced by special pleading about the measurements, and for the two other events, where the rate of warming stopped, it was virtually indeterminate. Neither study provided a clear demonstration that increasing CO2 concentration precedes warming.

The major reduction in temperature at the end of the last warm period, 130,000 years bp, precedes the change in CO2 by some 8,000 years. In other notable cooling events (235,000, 320,000, and 410,000 years ago) temperature drops of 4 degrees occurred, with no change in CO2 concentration, over periods varying from 8,000 to 15,000 years. With these observations, it is difficult to accept that changes in CO2 concentration cause changes in global temperatures.

Models of expected temperature increases, based on a range of assumptions around the central hypothesis that CO2 concentrations are the main driver of temperature change were created 10-15 years ago, at the time when temperature rise coincided with CO2 increase (above). A comparison of the model outcomes, against present-day global temperatures, shows no correlation between the two; the alarming predictions of global warming have not happened.

In summary, to a layman, as outlined above:

1) The basic assumption of the importance of CO2 is overstated.

2) There is no evidence, on time-scales of years, decades or millennia, that changes in CO2 concentration have any causal effect on global temperature variations.

3) The models assuming that CO2 is the driver behind global warming manifestly do not match the observations; nevertheless, they are invoked to support the assumption.

4) The case that anthropogenic increases in CO2 concentration cause global warming appears to be based on circular arguments, special pleading and circumstantial evidence.

P.S. The academic, referred to above, also suggested reading ‘The Warming Papers’ by D. Archer and R. Pierrehumbert – a collection of scientific papers going back to the 18th century, which are the ‘Scriptures’ of Global Warming. The first of these, by Fourier, concluded that there was no heat output from the earth, based on the observation that his cellar kept a constant temperature throughout the year. However, he was not aware of later discoveries, such as the occurrence of ocean spreading, that would release heat. The second, by Tyndall, correctly identified both CO2 and water vapour as absorbers of infra-red radiation, but the importance of the latter seems to be overlooked. A third paper, by Aarhenius, was an analysis of atmospheric CO2 and temperature measurements, but contains much opaque circumlocution, besides special pleading to explain measurements that did not agree with his assumptions. In short, none of these writings provide convincing historical legitimacy for the hypothesis.

Biography  Peter F. Owen MA FGS. Degree in Geology in 1967. Working life spent in acquiring, processing and interpreting seismic data, initially with large companies, latterly as an independent consultant.  Particular interest in creating models for predicting porosity and seismic velocity in sand/shale mixes.


  1. Richard Piggin says:

    Dear Peter,

    I was very interested to read your article on the Warren Consulting website, which is the first one I have seen which addresses the “elephant in the room” of the probable effects of water vapour on global warming.

    In the past several years I have attended several presentations on energy & climate change, and was distressed by the waffle generally offered (projections of Swiss energy requirements for 50 years …!). Accordingly, some time ago I prepared a short tutorial on the available energy sources, mainly for my own instruction & benefit but also to inform/bore friends who might also feel concerned, because I was fed up with the obviously biased information shrilly emanating from various lobbies and the manifest self-interest & lack of courage of the press & politicians “to tell it like it is”. My approach was first to review the evidence for global warming in the light of climatic variations somewhat longer in time than the attention span of most politicians, and secondly to try to see what the physics tells us might be feasible energy sources among the various mooted energy alternatives.

    During my investigations, it quickly because apparent that:
    + over the past millennia, there have been several major episodes of global warming/cooling which could not have been caused by anthropogenic means; a fact you pointed out but is overlooked by the lobbies & politicians
    + no one seems to have seriously evaluated if in the past century there has been a significant worldwide increase in atmospheric water vapour, which is emitted in more copious amounts than CO2 by any hydrocarbon source (eg: CH4 +2O2 = CO2 + 2H2O!) and whether this could account for “climate change” in the form (perhaps ?) of measureably increasing precipitation
    + few people seem to have noticed, as you also point out, that the past increases in atmospheric CO2 occurred several hundred years after a warming cycle has started, and that there is also an anti-correlation between temperature and atmospheric dust concentration which would presumably affect earth’s libido
    + no politician has seriously compared the health hazards and other advantages/disadvantages of using the various different energy sources, and that it is generally agreed that current sources are acceptably “safe” but new ones are unacceptably “dangerous” (especially nuclear energy); the truth seems to be the opposite !
    + most of the currently touted “solutions” involve implementation costs which will bankrupt western economies, or at least make them uncompetitive with others who are not so environmentally responsible
    + it seems nevertheless that the increasing surface seawater acidity is a new phenomenon which could well be tied to the increasing atmospheric CO2 concentration

    The only books which I found which seem to address the issue from the science rather than the politics are the following;
    “Sustainable energy without the hot air” by David JC Mackay
    “Physics for Presidents” by Richard Miller
    to which I would refer you if you haven’t seen them already, and to my agreeable surprise, there is a wealth of useful and seemingly unbiased information on Wikipeda

    In case you are interested, I am attaching a pdf copy of my tutorial, which has turned out not to be as short as intended, but I would be pleased to receive any comments, suggestions and particularly corrections to my figures & calculations (…. the conversions from one set of units to another are very confusing !) which you may have.

  2. David Stevenson says:

    Dear Peter

    Your article may appear largely plausible to the layman, but contains many scientific flaws, too many to directly address here. Water vapour is acknowledged to be the most important greenhouse gas in Earth’s atmosphere (in terms of its effect on radiation). However, the direct human influence on its atmospheric concentration is small, as it is swamped by the natural water cycle. There is however, an important indirect human influence on water vapour – namely via increases in the other, dominantly anthropogenic, greenhouse gases, such as CO2. Increases in CO2 warm the lower atmosphere (for the reasons you describe). Warmer air can accommodate more water vapour molecules, so the water vapour concentration increases. Since water vapour is a greenhouse gas, this amplifies the warming.

    To obtain the expert’s views on CO2’s influence on climate change, I suggest reading this recent overview prepared by the Royal Society and the US National Academy of Sciences, which answers many of the key questions, and corrects some of the flawed science presented above.

    Cheers, David

  3. David,

    Your reasoning here is highly dependent on the “appeal to authority” argument.

  4. David Stevenson says:


    Well, i’d describe it as holding a greater degree of trust in climate scientists and the peer-reviewed scientific literature, over an individual posting on an oil industry website. This choice is grounded in a scientific education (I have degrees in Geophysics and Meteorology), a highly skeptical attitude to authority, and twenty years of research on these topics.

    I guess that makes me a dangerously biased insider. But who would you ask for information on cancer? A qualified doctor, or a random blogger? I know who i’d ask. (Actually i’d try and ask several of the former, and become increasingly confident if they all told me roughly the same thing).

    Cheers, David

  5. Rob Schneider says:


    Name the “oil company website”.

    A common ploy of climate scientists is to attack credentials. Pity.

    See which has nothing to do with “oil companies” recent work by McKitrick and Vogelsang …

    “Over the 55-years from 1958 to 2012, climate models not only significantly over-predict observed warming in the tropical troposphere, but they represent it in a fundamentally different way than is observed.”

    A common ploy of climate scientists is to attack credentials. Pity.

  6. David Stevenson says:

    Err — Warren Business Consulting?

    Enough time wasted talking to flat-Earthers… Bye!

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