Saturday, April 7, 2012

Global Warming Is Bunk, Part 5: No Causation Without Correlation

This post contains the third chapter of a paper that I wrote three years ago as a critique of the science and politics behind the anthropogenic global warming (AGW) thesis. The paper was peer-reviewed but never published. The predictions that I made in this paper have been universally borne out.


3             Temperature does not correlate with either CO2 concentration or fossil fuel consumption

Why are declining temperatures a problem?  Apart from the fact that lower temperatures have historically had a demonstrably negative impact on human civilization, declining temperatures (see figure 6, below) completely undermine the AGW thesis.  As noted in the preceding section, all of the computer projections offered by the proponents of the AGW thesis over the past several decades have argued that global temperatures will only rise.  Falling temperatures demonstrate, therefore, that the theories upon which the computer models are based are fundamentally flawed.

Figure 6 - Comparison of observed temperatures and CO2 concentration[1]

Where do the flaws lie?  One obvious candidate is the models’ reliance upon the argument that the concentration of carbon dioxide in the atmosphere drives global temperatures.  While the pronouncements of the AGW advocates routinely include a cursory genuflection in the direction of other greenhouse gases (e.g., methane, although curiously never water vapour, which is both far more prevalent in the atmosphere than any other GHG, and is a far more effective greenhouse agent than CO2), carbon dioxide is the chief demon in their pantheon.  This is the Achilles’ Heel of the AGW thesis.

As one observer puts it, “The decadal correlation strengths (r-squared) of both the Hadley and MSU satellite with the corresponding CO2 is non-existent (r2=0.00)….It doesn’t take an advanced science degree to see there has been virtually no trend in the temperature data in the last decade or this century even as CO2 has increased 5.5%.”[2]

If we look back only over the period since the beginning of human industrial activity in earnest (which coincides roughly with the explosion of mechanization in the early part of the 19th century), we see that the concentration of CO2 in the atmosphere has risen consistently (see figure 10).  The proponents of the AGW thesis note a corresponding rise in average global temperatures during the same period, posit a causal relationship, and, on the basis of this supposition, conclude that human-produced carbon dioxide is responsible for rising temperatures.  This is the central contention of the AGW thesis.  But the facts are not quite as simple as that.  First, as noted above, the rise in temperature since the early 1800s is not at all surprising given that temperatures have in fact been rising since the end of the Little Ice Age in the early 18th Century.  The question then becomes, what proportion of the rise in temperatures – if any – is due to increasing CO2 concentrations rather than to a natural recovery from a prolonged cold period?
Figure 7 -  No correlation between CO2 and temperature over the past 600M years[3]

This is even more difficult to determine, principally because, as can be seen from figure 6, the causal relationship between carbon dioxide and global temperatures posited by the proponents of the AGW thesis does not appear to exist.  The AGW thesis, after all, is founded on the assumption that temperatures always rise in lockstep with CO2 concentrations,[4] but as figure 6 shows, the past seven years of observed data demonstrate that, while CO2 concentrations have continued to rise, temperatures have fallen.  This contradicts the AGW thesis.

Observed data pose the same problem for the AGW thesis over longer time scales.  As may be seen in figure 7, there is no correlation between average global temperatures and the concentration of atmospheric CO2 as determined from archaeological data.  As Robinson, Robinson and Soon note,

The 650,000-year ice-core record does not, therefore, agree with the hypothesis of “human-caused global warming,” and, in fact, provides empirical evidence that invalidates this hypothesis.[5]

Average global temperatures have gone up and down cyclically, while carbon dioxide concentrations have fluctuated, with neither demonstrating any clear pattern.  At present, in fact, CO2 concentrations are near an historic low; one scientist recently described the Earth as being in a state of “famine” with respect to carbon dioxide: 

Many people don’t realize that over geological time, we’re really in a CO2 famine now. Almost never has CO2 levels been as low as it has been in the Holocene (geologic epoch) – 280 (parts per million - ppm) – that’s unheard of. Most of the time [CO2 levels] have been at least 1000 (ppm) and it’s been quite higher than that.[6]

As Ball shows in figure 7, the only time in history that both temperatures and CO2 concentrations have simultaneously been as low as they are at present was during the late Carboniferous and early Permian eras, roughly 300 million years ago – long before the emergence of primates, let alone humans.  For most of Earth’s history, the concentration of CO2 in the atmosphere has been ten or more times greater than today’s level – all without any coal-fired generating stations or SUVs.

On some time-scales, it is possible to see a correlation between CO2 concentrations and global temperatures.  In reviewing ice core data, for example, the similarity between the curves representing CO2 and methane concentrations and the curve representing average global temperature over the past 650,000 years is obvious (see figure 8).[7]  However, what is important here is not only the apparent correlation between the two curves, but the direction of the “arrow of causation” – i.e., the answer to the question, “which came first: higher CO2 concentrations, or higher temperatures?”

Figure 8 - Changes in atmospheric concentration of CO2 and methane have lagged temperature changes for 650,000 years[8]

Closer examination of the curves provides the answer, and it is one that has been reached by many students of paleo-climate: that increases in CO2 and methane concentration follow temperature increases, by hundreds of years, rather than preceding them.[9]  An earlier phenomenon cannot have been caused by a later one, a principle fixed firmly in the laws of thermodynamics, and one that might best be expressed by the logical maxim, Ante hoc, ergo non propter hoc (“It came before, therefore it was not caused by”).  While pre-historic increases in CO2 concentration may therefore have been a result of increasing temperatures, they cannot have been a cause of them.[10]  A physical dynamic that endured for half a million years is unlikely to have spontaneously reversed itself in the last century and a half.
Figure 9 - The fact that temperature both rises and falls at identical CO2 concentrations demonstrates that there is another, more important, driver at work[11]

Proponents of the AGW thesis have attempted to rescue their theory from the implications of lagging carbon dioxide concentrations through special pleading.  Hansen, for example, has suggested that the lag is explained by solar and/or orbital changes producing a minor increase in temperature, which induces some CO2 off-gassing, which thereafter drives temperature increase; however, as Lansner notes, this does not explain subsequent temperature declines despite proportionally high levels of CO2 concentration; nor does it explain how the same levels of CO2 concentration could cause temperatures to both rise and fall (see figure 9).  This could only happen if changes in CO2 concentration are the result, rather than the cause, of changes in temperature.  Some other factor must be driving global temperatures.

Figure 8 also, incidentally, makes two other important points.  The first is that both temperatures and carbon dioxide concentrations are, at present, near the low end of historical maxima.  The second is that, for the past half-million years, temperatures have been remorselessly cyclical.  Given that the large-scale human consumption of fossil fuels took place only during the far right millimetre of the temperature chart at figure 8, the IPCC’s key argument – that temperature change is driven largely by carbon dioxide emitted by human industrial activity – is not logical.

Recent analysis of data concerning seasonal variations in CO2 concentrations in the northern hemisphere, and on the time delay between northern and southern hemispheric changes in CO2 concentration, suggests that the source of recent increases in global CO2 concentration may, in fact, be largely natural rather than anthropogenic.[12]  If this analysis is accurate, then the founding assumption of the AGW thesis – that the apparent correlation between world fuel consumption and global CO2 concentration is, in fact, causal – may be incorrect.

It is often said, and correctly, that “weather” is not “climate”, and that cold temperatures cannot be taken as proof of global cooling, nor hot temperatures as proof of global warming (although proponents of the AGW theory regularly do so).  However, it has also been said that “climate is what you expect; weather is what you get.”[13]  Seven straight years of declining temperatures is not “weather”; it is “climate”.  A warming climate is what the proponents of the AGW theorists expected; a cooling climate is what they got.  Observed data proceeded in the direction opposite to that predicted by the theory.  This calls into question the validity of the theory itself.

Physicist Henrik Svensmark, a researcher at the Danish National Space Centre, notes –  concerning the apparent correlation between CO2 and temperatures over the past century – that half of the warming over the 20th century occurred during the period 1905-40, when carbon dioxide levels were still comparatively low; that temperatures dropped significantly in the 1950s and 1960s, when carbon dioxide concentrations were increasing rapidly; and that, since 1998, carbon dioxide concentrations have continued to climb, but temperatures have fallen.  Thus, even the apparent correlation of the past century is, in reality, no correlation at all[14] (this dynamic can be seen at figure 10).

Svensmark summarizes thusly the case against carbon dioxide as the principal driver of global temperatures:

·         over the past 500 million years, there has been no correlation between carbon dioxide and temperature;

·         over the past million years, there has been a correlation, but the other way around – with increases in temperature preceding increases in carbon dioxide concentrations, rather than following them;

·         over the past 10,000 years there has been no correlation between carbon dioxide and temperature; and

·         over the past 100 years, there has been a “rough link” between increasing carbon dioxide and temperature. [15]

The lack of a correlation becomes even more obvious when one considers that the AGW theory deems not merely carbon dioxide, but human-produced carbon dioxide, to be the key determinant of climate.  Human industrial activity, i.e. consumption of fossil fuels, is supposed to be driving “climate change”.  However, just as there is no correlation between atmospheric CO2 concentration and average global temperature, neither is there any correlation between human fuel consumption and average global temperature.

Figure 10 - World Fuel Consumption vs. Global temperature anomalies 1861-2000[16]

(Legend: Thin dashed line = annual temperature anomaly; bold line; 13-year smoothing; boxed grey line = world fuel consumption (Mt of nominal fuel).

As may be seen in figure 10, global fuel consumption rose slowly from 1861 to about 1950, rose very rapidly from about 1950 to the late 1980s, declined briefly, and then began rising again in the mid-1990s.  Throughout this same period, however, global temperature anomalies did not correlate with fuel consumption; they were, as they always have been, remorselessly cyclical.

Table 1 provides Klyashtorin and Lyubushin’s summary of the lack of correlation between the two phenomena. As will be seen from this table, global temperature anomalies and world fuel consumption exhibit a close positive correlation only during two periods: 1861-1875, and 1975-2000.  Between 1875 and 1910, fuel consumption was rising significantly, but temperatures were falling, resulting in a strong negative correlation.  Klyashtorin and Lyubushin remark that the period from 1910 to 1940 is of “particular interest”, because while WFC showed almost no increase (due to the economic consequences of the Great Depression), global temperature rose by more than 0.4ºC.  The result is a positive, but very loose, correlation.  Finally, between 1940 and 1975, fuel consumption increased by a factor of 2.5, while temperature decreased by 0.12ºC, resulting in a strong negative correlation.  On the basis of these data, Klyashtorin and Lyubushin conclude that “no true linear correlation exists between the Global dT and WFC dynamics for the last 140 years.”[17]

Table 1 - Correlation between Δt and WFC in different time periods from 1861-2030                   (after Klyashtorin and Lyubushin[18])

Temperature Trend
Coefficient of Correlation
(Δt and WFC)
+ 0.92
- 0.71
+ 0.28
- 0.88
+ 0.94
Falling (?)

The lack of any discernible correlation between global temperature anomalies and world fuel consumption since the mid-1800s undermines the key pillar of the AGW thesis – that it is not only carbon dioxide, but carbon dioxide resulting from human consumption of fossil fuels, that is responsible for warming the planet.  If this were true, then there would be a consistent, close, positive correlation between world fuel consumption and global temperature over the past century and a half.  But there is not.

Dr. David Evans, the consultant who designed the carbon accounting model that measures Australia’s compliance with the Kyoto Protocol, has, in view of observed data, reversed his previously-held opinions on the sources of climate change.  In an article published in July 2008, he described his current understanding of the empirical foundations of climate science thus:

There is no evidence to support the idea that carbon emissions cause significant global warming. None. There is plenty of evidence that global warming has occurred, and theory suggests that carbon emissions should raise temperatures (though by how much is hotly disputed) but there are no observations by anyone that implicate carbon emissions as a significant cause of the recent global warming…

The world has spent $50 billion on global warming since 1990, and we have not found any actual evidence that carbon emissions cause global warming. Evidence consists of observations made by someone at some time that supports the idea that carbon emissions cause global warming. Computer models and theoretical calculations are not evidence, they are just theory.[19]

No evidence.  No correlation.  And where there is no correlation, there can be no causation.  Even worse (at least from the perspective of the AGW advocates), to the extent that there has been any historical correlation between carbon dioxide concentrations and global temperature, the causal relationship appears to be opposite to that assumed by the AGW thesis.  Temperature changes lead and therefore drive changes in CO2 concentration, rather than follow, and therefore result from them. 

This, incidentally, is an unsurprising conclusion given, first, that the world’s largest reservoir of gaseous carbon dioxide is dissolved in the oceans, and second, that the solubility of gases in water is inversely proportional to temperature.  As the oceans warm, we would expect dissolved CO2 to come out of solution, and the atmospheric concentration of CO2 to correspondingly increase.

The failure of either CO2 concentrations or the human consumption of fossil fuels to display any significant correlation with temperature over any time frame, recent or ancient, demonstrates either (a) that carbon dioxide and fossil fuel consumption play no significant role in driving temperature; or (b) that if they do, then some other factor or factors play a role that is so much more statistically significant that changes in carbon dioxide concentrations or fuel consumption appear to have no significant impact on climate. 

From the point of view of governments attempting to devise policy measures to “combat climate change”, there is no difference between these two possible conclusions.


[1] Joseph D’Aleo, “MSU Satellite Temperatures Continue to Diverge from Global Data Bases”, [ between_ co2_and_global_temperature/].  All of the data cited in this chart are available on-line.  The Mauna Loa CO2 data are at [].  The coefficients of correlation (r=-0.36 for the UAH MSU data, and r=-0.42 for the Hadley data), were calculated by the author of the post cited.  D’Aleo is a former Professor of Meteorology at Lyndon State College, who served as the first Director of Meteorology for the cable television Weather Channel.
[2] Joseph D’Aleo, “Correlation Last Decade and This Century Between CO2 and Global Temperatures Not There”,, 18 March 2008, [].
[3] Dr. Timothy Ball, “Measurement of Pre-Industrial CO2 Levels”, Friends of Science, November 2008, 6 [].
[4]Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations.”  IPCC, Summary for Policymakers, 4th Assessment Report (2007), 5.
[5] Arthur B. Robinson, Noah E. Robinson, and Willie Soon, “Environmental Effects of Increased Atmospheric Carbon Dioxide”, Journal of American Physicians and Surgeons 12 (2007), 85.
[6] “Many people don’t realize that over geological time, we’re really in a CO2 famine now. Almost never has CO2 levels been as low as it has been in the Holocene (geologic epoch) – 280 (parts per million - ppm) – that’s unheard of. Most of the time [CO2 levels] have been at least 1000 (ppm) and it’s been quite higher than that.”  Testimony of Dr. Will Happer, “Update on the Latest Global Warming Science”, US Senate Committee on Environment and Public Works, 25 February 2009.  Dr. Happer is the Cyrus Fogg Brackett Professor of Physics at Princeton University; his full testimony may be found at [ public/ index.cfm?FuseAction=Files.View&FileStore_id=84462e2d-6bff-4983-a574-31f5ae8e8a42].
[7] A similar graphic, complete with cited sources, may be seen at [ gw/paleo/400000yrfig.htm].
[8] Christopher Monckton, “Letter to Representatives Ed Markey and Joe Barton”, 30 March 2009 [].  The Vostok Ice Core data are available on-line at [].  Monckton’s data are derived from J.R. Petit, et al., “Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”, Nature 399 (1999), 429-436. Another author notes that “A review of the recent refereed literature fails to confirm quantitatively that carbon dioxide (CO2) radiative forcing was the prime mover in the changes in temperature, ice-sheet volume, and related climatic variables in the glacial and interglacial periods of the past 650,000 years”.  Willie Soon, “Quantitative implications of the secondary role of carbon dioxide climate forcing in the past glacial-interglacial cycles for the likely future climatic impacts of anthropogenic greenhouse-gas forcings”, preprint in press for Physical Geography, 4 July 2007 [ uploads/Soon07-CO2-TempCORR-Preprint.pdf].
[9]Over the full 420 ka of the Vostok [ice core] record, CO2 variations lag behind atmospheric temperature changes in the Southern Hemisphere by 1.3 +/- 1.0 ka [thousand years].”  Manfred Mudelsee, “The phase relations among atmospheric CO2 content, temperature and global ice volume over the past 420 ka”, Quaternary Science Reviews 20 (2001), 583 [ relations_among_atmospheric_CO2_content_temperature_and_global_ice_volume_over_the_past_420_ka.pdf].  The same conclusions have been reached by many other researchers; see, for example, H. Fischer, t al., “Ice core records of atmospheric CO2 around the last three glacial terminations”, Science 283 (1999), 1712-1714; A. Indermuhle, et al., “Atmospheric CO2 concentration from 60 to 20 kyr BP from the Taylor Dome ice core, Antarctica”, Geophysical Research Letters 27 (2000), 735-738; E. Monnin, et al., “Atmospheric CO2 concentrations over the last glacial termination”, Science 291 (2001), 112-114; P.U. Clark and A.C. Mix, “Ice Sheets by Volume”, Nature 406 (2000), 689-690; and N. Caillon et al., “Timing of atmospheric CO2 and Antarctic temperature changes across Termination III”, Science 299 (2003), 1728-1731.
[10] Robinson, Robinson & Soon, ibid., 85.
[11] Frank Lansner, “CO2, temperatures, and ice ages”,, 30 January 2009 [].  Lansner’s analysis is based on data derived from peer-reviewed studies of inter alia Vostok ice core data from Antarctica.  These data are available on-line at [].  There are other examples in the archaeological record of changes in CO2 concentrations lagging temperature changes; for example.  One team looked at three separate sets of ice cores (Byrd, Taylor Dome, and Vostok) and concluded that "Atmospheric CO2 concentrations show a similar increase for all three terminations, connected to a climate-driven net transfer of carbon from the ocean to the atmosphere. The time lag of the rise in CO2 concentrations with respect to temperature change is on the order of 400 to 1000 years during all three glacial-interglacial transitions."  H. Fischer, et al., “Ice Core Records of Atmospheric CO2 Around the Last Three Glacial Terminations”, Science, Vol. 283. no. 5408 (12 March 1999), 1712 (DOI: 10.1126/science.283.5408.1712) [].
[12] Tom Quirk, “Sources and Sinks of Carbon Dioxide”, Energy & Environment 20, Nos. 1-2 (2009), 105-121 [].
[13] A witticism that has been attributed to both Samuel Clemens and Robert Heinlein.
[14] Henrik Svensmark and Nigel Calder, The Chilling Stars: A Cosmic View of Climate Change (Cambridge, UK: Icon Books, 2007), 247.
[15] Svensmark and Calder, ibid.
[16] L.B. Klyashtorin and A.A. Lyubushin, “On the coherence between the dynamics of the world fuel consumption and global temperature anomaly”, Energy & Environment, Vol. 14, No. 6 (2003), 775.
[17] Klyashtorin and Lyubushin, ibid.
[18] Klyashtorin and Lyubushin, ibid.
[19] David Evans, “No Smoking Hot Spot”, The Australian, 18 July 2008, [ story/0,25197,24036736-7583,00.html.]