Tuesday, June 2, 2009

A Backward Look at IPCC predictions of Temperature Rise

Today we are going to take a backward look at the IPCC's predictions about global warming to see if the past 40 years have behaved as they claim the next 40 years will behave.

The IPCC says this

"The equilibrium climate sensitivity is a measure of the
climate system response to sustained radiative forcing.
It is not a projection but is defined as the global average
surface warming following a doubling of carbon
dioxide concentrations. It is likely to be in the range
2°C to 4.5°C with a best estimate of about 3°C, and is
very unlikely to be less than 1.5°C. Values substantially
higher than 4.5°C cannot be excluded, but agreement
of models with observations is not as good for those

IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis.
Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
[Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.) Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA., P. 12 Source

They say that the temperature rise will go up 2 to 4.5 degrees for every doubling of CO2. The temperature rise due to CO2 is logarithmic and the math works out as follows:

T = 2 x ln(ending CO2 ppm/starting CO2 ppm)/ln(2x starting CO2 ppm/starting ppm)
(ppm is parts per million of CO2)

Let's first see how this warming compares to the satellite data. The Huntsville Satellite data started in 1979 and the starting ppm, in 1979, was 335 ppm. From that, and the rise in CO2, one can derive what temperature rise we should have seen. I use the famous Keeling curve as the source for the CO2 rise in this calculation. It is the most often cited CO2 curve and is often used to scare the hell out of all of us. that is the picture below.

I want to emphasize that in the pictures above and below all the curves are TEMPERATURE not CO2. For the satellite data they are the predicted temperature with
the starting CO2 being the CO2 ppm in 1979, (335 ppm) and the ending being
the CO2 in 2007 (388 ppm). The 2x starting is 670 ppm, so the curves are what we should expect for the temperature rise since 1979. Clearly we have
been way below the expected.

The equation since 1979 is 2 x ln(current year CO2ppm/335)/ln(670/335) or
5 x ln(current year co2ppm/335)/ln(670/335).

One can clearly see in the expected temperature rise expected due to CO2 far far out ran the observed rise as measured by the satellites. This clearly indicates that the above quotation from the IPCC is utterly flawed. The world's temperature is NOT rising at either 2 or 4.5 or even 5 (as some older sources declared). And it shows that it is NOT going to rise in the future at the scary rate they claim.

Now lets look at the global temperature anomaly derived from NOAA's Global Climate at a Glance. I plotted the global temperature anomaly since 1958, when the Keeling Curve, the most often cited CO2 curve. In this case the starting CO2 is 315 ppm in 1958. Once again, the world is not warming as predicted by the IPCC. The temperature rise is far smaller than what would be expected.

This, to me, says that the IPCC is nothing but a scaremongering organization. Their predictions of the effect of CO2 has not worked out in the past but we are expected to believe that it will work out as they say in the future. Why should we believe them? Surely someone somewhere has plotted the data as I just plotted it to see if the past matches the predictions these guys are making. That would just be good science. But I have never ever seen anyone do what I just did. Is it possible that the IPCC isn't publishing things like this, which might make people think that the world isn't behaving as they say it will as the 'temperature kills civilization?


  1. Can I ask why on your first graph your two "calculated" trends start at 0 whereas the actual temperature trend starts at about -0.2degrees? It almost looks as if you shifted the curves down the proper place that the actual temp curve would sit somewhere within the two calculated curves.

    I'm a pretty simplistic guy so I took the data and graphed CO2 vs temperature from the sets you linked when I fitted a curve to it I came up with an equation that was:

    T = 4.193*ln(CO2) - 24.576

    When you plug 334.95ppm CO2 into it (the starting CO2 level in the data set) you get -0.19degrees, not too far off from the actual data of -0.165degrees. Then when you plug in the doubled CO2 concentration of 669.9ppm CO2 the temperature kicked out by the equation is 2.7degrees. Which works out just about 2.9degrees difference, which is not too far from the middle point of the suggested range of 2 to 4.5deg difference with doubling CO2.

    But I also understand that this might be an oversimplification since the earth is capable of buffering the heat, and this sounds like it might be one of the more difficult areas to calculate owing to the various feedbacks in this calculation.

  2. The file I downloaded from U. of Alabama Huntsville has the values plotted. I would have had to have shifted the IPCC curve down -.2 to match the actual starting point of the satellite data, which, quickly went above zero anyway, but the equation which is used for calculating temperature increase above the 335 ppm level of CO2 in 1979 gives a zero for the starting point.

    I left all numbers as they came from their respective sources. If you like, I will, in a couple of days shift the IPCC curve to start at -.2 but it won't make any difference to the conclusion that the world isn't heating at the rate the IPCC says CO2 should heat the world.

    Now, I do see your point about the shift would move the 2 deg closer to the satellite data, but it won't move it closer to the global temperature anomaly for the past 50 years. I would suggest that the satellite record would say that the world can't be warming at more than 2 deg per doubling but the global temperature anomally data says we are warming over a longer term at a significantly slower rate.

    To me the interesting thing is that in order for the 2+ deg/doubling to be valid, one must find a large and I mean a very large, heat sink. Some calculations I did a while ago say all that heat can't be stored in the oceans or we would have seen far more warming there. Indeed, since 2003 the oceans are cooling. I am eagerly waiting for NOAA to put out the 2008 data in their Global Climate at a Glance. Last year at this time they already had 2007 out there. It seems very likely that their data will show 2008 was cooler because there were 100+ year temperaturerecords all over the globe that fell in 2008. At least I expect it to be cooler--the snow says it should be cooler.

  3. I have posted a link to the above on RealClimate.org in the "Monckton" thread. It is approximately post # 452.


  4. This comment has been removed by the author.

  5. That must explain why I got a note from a guy telling me thanks and that he thought Real Climate was a 'rabid AGW' site--his words. And I agree. Real Climate isn't interested in scientific debate about the issues, they are interested in squashing questions.

    I don't see Real Climate as authoritative. I see them as merely political advocates, not scientists.

    If they want to comment, let them come here. I don't waste my time there any longer

  6. I just discovered your site. I can't understand why, in this exercise, you ignored all other forcings, and then thought it was valid to compare your computed temperatures to actual.

    It should be fairly easy to fix. Particulates and insolation should be all that's significant. Insolation is exceptionally easy and with little error. My hunch is that if you do the insolation first, you will find that it will explain most of the discrepancy.