Increasing CO2 Raises Global Temperature Or Does Increase Temperature Raise CO2

On 24 July 2012 in a lecture at Sydney Institute, Professor Murray Salby clearly demonstrated the  widely held belief, promoted by IPCC, is wrong.  It is not rising CO2 which leads to increased global temperature.  Increasing temperature leads to rising levels of CO2.  More importantly this rise in level of CO2 is due to natural not human activity.

This means all the effort and money being spent on reducing human CO2 emissions is waste of time and money.

There is a link to video of the lecture at the end of this post but first a short summary.

IPCC models show global temperature rising over the next 100 years like this.


The models show the rise in temperature almost exactly matches the assumed rise in CO2. This should come as no surprise as it’s built into the models.



But when we look at actual  global temperatures compared to measured levels of CO2 this correlation between temperature and CO2 does not exist, certainly since 1997. It looks as though there may appear to be a correlation in the late 1980s possibly as far as 1997 but as people are taught repeatedly in statistics classes

Correlation is not causation

Correlation is not causation

It could just have been a coincidence which lasted 5 to 15 years and projecting the same correlation will continue for the next 100 years is just silly.  Especially when we can see there is no correlation over at least the last 15 years.


The amount of CO2 in the atmosphere does not increase at a steady rate.  For one thing there is a difference between winter and summer, as the following graph shows.  The graph also shows some years there is a bigger increase and others hardly any at all.



The following graph which shows the change in CO2 levels (rather than the levels directly) makes this much clearer.


There are big swings in the amount of CO2 emitted.  Taking the mean as 1.6 ppmv/year (at a guess) there are +/- swings of  around 1.2 nearly +/- 100%.

And, surprise surprise, the change in net emissions of CO2 is very strongly correlated with changes in global temperature.

corTempChangeCo2EmissionThis clearly indicates the net amount of CO2 emitted in any one year is directly linked to global mean temperature in that year.

For any given year the amount of CO2 in the atmosphere will be the sum of

  • all the net annual emissions of CO2
  • in all previous years.

For each year the net annual emission of CO2 is proportional to the annual global mean temperature.

This means the amount of CO2 in the atmosphere will be related to the sum of temperatures in previous years.

So CO2 levels are not directly related to the current temperature but the integral of temperature over previous years.

The following graph again shows observed levels of CO2 and global temperatures but also has calculated levels of CO2 based on sum of previous years temperatures (dotted blue line).


What you have just read is enough to kill the CO2 is responsible for global warming claim stone dead.

But there’s more.

The following graphs shows the discrepancy between models and observations of incoming visible (Short Wave) light and outgoing infrared radiation (Long Wave).

The discrepancy is about 30 wm-2 for incoming SW and 20 wm-2  for LW.

But the amount of warming IPCC attribute to CO2 is 4wm-2

In other words the claimed CO2 affect is swamped by discrepancies an order of magnitude larger!


I strongly urge you to watch  Professor Salby’s 2012 lecture to Sydney Institute.

Hat tip to The Hockey Schtick for providing the link.

Why not watch Professor Salby’s 2011 lecture to Sydney Institute.









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4 Responses to Increasing CO2 Raises Global Temperature Or Does Increase Temperature Raise CO2

  1. The change in net emissions per year says next to nothing about the cause of the increasing trend.
    In fact the year by year increase in CO2 is influenced by two (and more) variables: human emissions and temperature (and drought and…). Salby completely forgets the human emissions. If you plot them together with the increase in the atmosphere, you will see that these always are higher than the increase in the atmosphere, in average twice the increase. See:
    Thus nature was a net sink for CO2 for every year in the past 50 years, not a source. The temperature caused variability in the increase rate is a variability in sink capacity of the natural balance and not the cause of the increase…

    • Jeremy says:

      Thanks for the comment Ferdinand

      Have you watched the Murray Salby’s 2011 lecture?
      here’s the link–9I

      In this lecture Murray explicitly considers human emissions and notes among other things

      a) They are 2 orders of magnitude smaller than net natural emissions

      b) The changes in net natural emissions do not correlate with changes in
      human emissions.

      Ice records show a decrease in the ratio of CO2 with C13 isotope to C12 overtime. Plants preferentially absorb C12 when photosynthesizing. The decrease in the C13/C12 ratio that accompanies the increase in atmospheric CO2 has been taken as evidence the increase was due to human activity (i.e. burning fossil fuels).


      Satellite measurements show changes in C13/C12 ratio in recent years is strongly negatively correlated with changes in global mean temperature. There was a sharp rise in C13/C12 ratio around time of Mount Pinatubo eruption and a sharp fall around the time of 97/98 El Nino. Remember net CO2 emissions are strongly positively correlated with changes in global mean temperature

      This strongly suggests that human activity is not the cause of changes in net CO2 emissions, unless one believes human activity causes volcanoes and El Ninos.

  2. Jeremi,

    I have looked at the recent lecture of Dr. Salby for the Sidney Institute, not (yet) at the older one, but the objections are the same:
    What Dr. Salby looks at is the year by year variability which shows a high correlation with (ocean surface) temperature variability. From that he concludes that the whole yearly rate of change is caused by temperature, but that is only true if temperature was the only cause of the increase. The formula for calculating the correlation doesn’t use the trend at all: you will find the same correlation, no matter if you look at the detrended rate of change (which makes that the integral over the period of interest = zero) or the real rate of change. Thus one can’t attribute the whole year by year net increase in CO2 to temperature, only because of the good correlation in variability between these two. The trend itself can be 100% from temperature (but where does the human CO2 go?) to zero from temperature and 100% from the human contribution…

    The fundamental error that Dr. Salby made is by only looking at the emissions side: nature delivers 97% of the emissions. But nature also absorbs 98.5% of the emissions. The net effect is that nature is a net sink of 1.5% of the combined emissions, while humans contribute 3% of the emissions, without appreciable sinks. Thus 97% of all natural flows in and out is simple throughput, without any effect on the CO2 levels in the atmosphere. The 3% human emissions is what makes the difference: without human contribution, nature would currently be a net sink for CO2… Temperature variations only modulate the sink rate, not the increasing trend (except for a small amount due to warming oceans over time).

    • Jeremy says:

      Hi Ferdinand

      Murray Salby considers net emissions, which includes human and natural sinks and sources.

      Thus your claim Salby doesn’t consider sinks or human emissions is not right.

      Most people who have even a smattering of statistics have heard the mantra
      Correlation is not causation

      But given there is a correlation of 0.93 between changes in temperature and changes in
      net CO2 emissions are you actually saying the changes in CO2 emissions have nothing to do with
      changes in temperature?

      People talk about human emissions but this is actually a hard number to determine
      as far as I know people make and estimate based on the amount of fossil fuel that is
      dug up and sold. Probably not terribly accurate.

      The observed swings in net CO2 emissions are roughly +/- 100% of mean amount.

      Is there a reason to think human emissions vary by this amount probably not,
      and if they did it would be hard to explain why the variation correlated so strongly
      with temperature.

      The alternative idea, natural CO2 net emissions vary with temperature, seems a lot easier to accept.

      When you add in the observation levels of CO2 have continued to rise since 1997/8 yet global mean temperatures have not it is difficult to avoid the conclusion Murray Salby reached, namely net CO2 emissions follow changes in temperature and CO2 is not responsible for changes in global mean temperature.

      It’s definitely worth watching the 2011 lecture and when I get a spare hour or two I’ll post a summary

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