Which Causes which out of Atmospheric Temperature and CO2 content?

Over very long periods of time as ice ages come and go, it has been found that temperature leads atmospheric CO2 content by about 800 years. This seems to contradict the IPCC and other views that CO2 causes change in temperature. But we are looking at very different time scales with present changes, so perhaps things happen differently. I decided to examine this question.

The temperature data used is monthly global land-ocean temperature or GHCN, which is available from NOAA. The atmospheric CO2 data used is from Mauna Loa in Hawaii, the longest continuous record of CO2 also available monthly.

When wanting to find the causation when two series are both increasing over time, it is best to look at the rate of change of the variables as this will show clearly which one precedes the other. This first graph shows the rate of change of these two variables monthly over the period 1958 to 2009.

Rate of change of atmospheric CO2 content and land-ocean temperature

Rate of change of atmospheric CO2 content and land-ocean temperature

Both monthly series were processed in the same way. The change over a 12 month was calculated, and a 12 month simple moving average of these values was used to avoid all seasonal effects. That data was plotted at the centre of the 23 months values used in the calculation. Because the treatment was the same for both variables, they are directly comparable.

It can be seen that there is generally a good correlation, with nearly all peaks in one variable  having similar peaks in the other. When one has a smaller peak such as around 1975, then so does the other. When one has a larger peak around 1973 or 1998, then so does the other. there are one or two minor variations from this.

It is also evident that the red temperature graph generally precedes the black CO2 graph on turning points.  This suggests that temperature drives CO2 and not the other way around. A comparison of the two series at different lags gives this second graph.

Correlation between rate of change of global temperature and rate of change of atmospheric CO2 content

Correlation between rate of change of global temperature and rate of change of atmospheric CO2 content

When the two series are coincident the correlation is quite small, r=0.13, whereas when temperature change 6 months earlier is compared to to CO2 change there is a maximum correlation of r=0.42 which is a high correlation for short period changes which have a high noise content. There is no high correlation for any lag when CO2 precedes temperature, the best being r=0.15 at 42 months.

It seems that, contrary to popular wisdom, temperature changes are driving atmospheric CO2 content changes, with a lag time of 6 months.

About Ray Tomes

Ray's career was in computer software development including system software design, economic modeling, investments. He spent 15 years full time on cycles research and has spoken on cycles and related topics at conferences and seminars around the world. He retired at age 42 to study cycles full time and work out “The Formula for the Universe” and as a result developed the Harmonics Theory as an explanation for observed patterns of cycles and structure of the Universe. His current project is the development of CATS (Cycles Analysis & Time Series) software, and collecting and organizing large quantities of time series data and analyzing this data to test and confirm Dewey's findings in an organized way. Interested in all aspects of cycles especially climate change and causes.
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30 Responses to Which Causes which out of Atmospheric Temperature and CO2 content?

  1. Pingback: Global Warming vs Global Cooling ... Can the earth Survive?

  2. John Nicol says:

    I think this finding is intersting but needs to be treated with some caution in being used to quell the suggestion that carbon dioxide causes warming. The geological 800 year lag is more substantive, as the large changes in both temperature and CO2 do not show any acceleration in warming as CO2 builds up and in fact the rate of warming declines as carbon dioxide increases, leading to a slower rate in CO2 release. Also the maximum CO2 precedes each ice age. In the short term however, one might expect that as the temperature falls, sea absorption of CO2 reduces the level as can be seen in the annual concentration of carbon dioxide, where the cooling of the hemisphere with the largest sea surface, lowers the CO2. I am not contradicting your article , nor claiming it doesnot show the lack of correlation claimed by the IPCC. I am just warning against complacency when the inevitable critics arrive.

  3. Ray Tomes says:

    John, Thanks for your thoughts.

    When I mentioned this post in the SpaceTimeandtheUniverse forum (see pingbacks above) it was pointed out that I didn’t really mention the cycles. Fair comment. The CO2 record shows a strong 1 year cycle which is easily understood as seasonal fluctuations in temperature, plant processes, sea temperature and human energy use.

    There is also evident a strong cycle of about 3.4 years in both temperature and CO2 rate of change graphs. This is a very commonly reported cycle according to Edward R Dewey, and is associated with interest rates and stock prices. Perhaps this is evidence that short term climate changes are driving those cycles. Something for looking at another day.

  4. Pingback: Which Causes which out of Atmospheric Temperature and CO2 content? « tallbloke's talkshop

  5. Richard C (NZ) says:

    Ray, this is timely. I’ve just plotted 1850 – 2010 CO2 vs GMTA minus oscillations and it clearly shows temp leading CO2 over the 1978 – 1998 warming period by about 20 years.

    The CO2 series is Law Dome – Mauna Loa and the same that is used to initialize the models. I fitted a 4th order polynomial trend curve for the exercise.

    The GMTA is HadCRUT3. Scafetta (2010) found an underlying quadratic trend and I’ve used that.

    I normalized the two series by zeroing at 1850 as per Scafetta. The plots are in the spreadsheet below.


    These plots are not proof of causation that temp actually drives CO2 but it certainly precedes it, ruling out the possibility of CO2 driving temperature.

    Richard Cumming

  6. Ray Tomes says:

    Please see further discussion on Tallbloke’s Talkshop at http://tallbloke.wordpress.com/2011/06/26/which-causes-which-out-of-atmospheric-temperature-and-co2-content/

    Also, Roy W. Spencer has shown similar results and the connection to ENSO in this article several years ago http://www.drroyspencer.com/2009/05/global-warming-causing-carbon-dioxide-increases-a-simple-model/

  7. Pingback: The Strata-Sphere » CO2 Does NOT Cause Climate Temperature Changes

  8. Pingback: Analysis of BE10 records as a Solar Irradiance Proxy | Cycles Research Institute's Blog

  9. Ken Stewart says:

    Gday Ray
    This is welcome confirmation of results anyone can show, see http://kenskingdom.wordpress.com/2011/04/12/co2-and-temperature/
    It’s definitely not the other way around!

    Ken Stewart

  10. G.S. Williams says:


    There is another aspect to the CO2 to Temp comparison, and that is the logarithmic graph showing the first 20 ppmv holding back enough heat to increase the temperature by six degrees C, but when the CO2 reaches 280 ppmv the heat held back is only .7deg C. I think, therefore, that CO2 is not capable of creating anything like dangerous warming due to the “diminishing return’. Also, CO2 , at approx 937ppmv stops affecting the temperature, so there still can be no AGW, it’s an impossibility.

  11. Peter Harris says:

    1.Good to see these data which show a small decline in line with T since 1998. Have you an opinion on the Keeling data posted by NOAA? That data is fundamental to the AGW claim.
    It has always been almost linear and uniform and does not even show a response to the 1998 peak T .yet it shows seasonal blips also perfectly regular.
    2 On a related subject have you a reference to a complete analysis of ALL (including long term) of the solar cycles? .

  12. Ray Tomes says:

    Hi Peter
    1. No, not my area of expertise.
    2. Wikipedia has a quite good list in http://en.wikipedia.org/wiki/Solar_variation (it is bizarre that this page has the cycles rather than the solar cycle page). It lists 11, 22, 87, 210, 2300, 6000 year cycles. I would say that all but the last are well established. There are a few others such as 105 and 355 years not mentioned here which are surely real. This does not include the shorter cycles (27, 77, 155 days etc) but they are not so relevant I think to your interest. See the other pages on this blog for cycles in long term proxy series:
    Regards, Ray

  13. Ray Tomes says:

    It is interesting to note that the 1992 deep trough in temperature attributed to Mt Pinatubo was followed by a similarly deep trough in atmospheric CO2 (deepest since 1975). If humans were the cause of CO2 change, then this should not have happened.

  14. Peter Harris says:

    Thanks for the solar cycle links. Another two questions please.
    1.I wonder if anyone has attempted to integrate all of the solar cycles which would provide long term variations that might be matched with major climate changes in the past?
    2.The Mauna Loa CO2 data published by NOAA does not show the dip in T in 1992 nor 1975 nor a peak in 1998..
    How did you arrive at your data (which I believe to be correct) ?

  15. Ray Tomes says:

    Hi Peter
    (1) There have been several attempts to put together solar cycles to determine the solar component of climate change. I don’t think that this has been done in a fully satisfactory way yet. Part of the problem is the mixing of proxies for older climate data with instrumental records for the recent past. Proxies do not generally show the full range of past variations, and they end up starting to look like the hockey stick in the extreme case of inappropriate proxies (tree rings only). Another problem is the longest cycles which are difficult to distinguish from any possible human caused trend. The 2300 year cycle is increasing at present and for the foreseeable future.
    (2) As stated, “The change over a 12 month [period] was calculated, and a 12 month simple moving average of these values was used to avoid all seasonal effects.” This is not what is normally graphed – usually they do the raw data. So I start with say the change from January 2000 to January 2001, then Feb 2000 to Feb 2001 etc through to Dec 2000 to Dec 2001 and then I average all of these figures. That values is then plotted at the beginning of 2001. The same processing is done to each of the CO2 and temperature records. So the lag of 6 months found is correct. Another researcher has done it a little differently, but finds the same 6 month lag. The advantage of this approach is that it avoids spurious correlations due simply to the continuous increase over time.

  16. fhhaynie says:

    I think you might be interested in an analysis I recently completed. I would be interested in your take on it. We Observe similar cycles but the timing is somewhat different.

  17. Ray Tomes says:

    Thanks fhhaynie, I think this is the link to your research:

    The difference in timing might be due to my graph showing rate of change.

  18. Allan MacRae says:

    RE: Which Causes which out of Atmospheric Temperature and CO2 content?

    I concluded in early 2008 that there is a ~9 month lag in atmospheric CO2 after temperature

    After being burnt at the stake for climate heresy (for suggesting that temperature primarily drives CO2, not the reverse), I was promoted to purgatory when both sides of the rancorous “mainstream climate debate” accepted this heresy as fact, but have dismissed it as a “feedback effect”, a notion for which there is no evidence, imo (but plenty of cargo-cult conviction).

    My icecap.us paper above was written ~3 years before Murry Salby’s address to the Sydney Institute in 2011, in which he made the same temperature-drives-CO2 hypothesis.

    Here is a more recent presentation to the Sydney Institute by Salby – it takes a while to load:
    [audio src="http://podcast.thesydneyinstitute.com.au/podcasts/2012/THE_SYDNEY_INSTITUTE_24_JUL_MURRY_SALBY.mp3" /]

    So my heresy is gaining some traction – and I’ll bet Murry Salby is feeling the heat.

    Regards, Allan MacRae

  19. Ray Tomes says:

    Thank you Fred. If a seasonal pattern is not6 a simple sine wave then it will contain harmonics of a year. For monthly data the harmonics up to the 6th can be measured. These variations will be real, but the mathematics limits their detection because the data is monthly. With daily data even more could be studied.

  20. Ray Tomes says:

    Allan, sorry for the delay. I couldn’t see this before, so thanks to David for approving. Also, thanks for the link to the video.

  21. Pingback: Human Activity is not the Cause of Climate Change, it is the Result | Cycles Research Institute's Blog

  22. Smokey says:

    This Wood For Trees chart shows the same thing:


    ∆T causes ∆CO2, not vice-versa. Those demonizing “carbon” have cause and effect reversed, and that is why they end up with incorrect conclusions.

  23. Pingback: Ray Tomes: Human Activity is not the Cause of Climate Change, it is the Result « Tallbloke's Talkshop

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