'The' graph which has its interest as a novel way of showing the log effect is becoming the point and the log effect issue is being ignored.

I don’t really want to argue the appropriateness of polys but if the physics that produced the data match the polynomial you are using for the fit, then the fit will match the curve, provided that the number of data points is higher than the order of the poly and there is no noise which is a bugbear for the high order polys.

The further point about AGW is there is no closed form model for climate over time anyway, so any fit will be inadequate, except for the linear fit. And that only shows the trend over whatever time period you pick for the fit. If you pick a long time period for the fit, then you will miss smaller time-scale changes, especially at the end points, and if you pick short time scales, then you will fit the short term variations, and miss longer trends.

In this instance we are talking about the AGW period which supposedly began about 1900. In this respect the log curve I linked to is not “vaguely reminiscent” of the log effect, it is exactly the log effect of extra CO2:

http://wattsupwiththat.files.wordpress.com/2010/03/co2_modtrans_img1.png

The issue is discussed here:

http://wattsupwiththat.com/2010/03/08/the-logarithmic-effect-of-carbon-dioxide/

A couple of points; this log decline is the inverse of the exponential which is how AGW sees the effect of CO2; that is, a runaway effect or the Venus Syndrome after a tipping point:

http://climatechangepsychology.blogspot.com.au/2008/12/james-hansens-agu-presentation-venus.html

Secondly, this graph also shows the log effect:

http://www.c3headlines.com/2014/01/per-noaa-20th-century-global-co2-warming-not-unprecedented-natural-warming-those-stubborn-facts.html

The graph is correct for CO2 but not apparently for temperature. Someone should ask the graph author.

The OLS linear trend from WFT shows the trend is greater in the second period and would therefore seem to contradict the point that temperature rose more from 1914-1963 with less CO2 than from 1964-2013 with more CO2.

Despite this the WFT graphs show the temp response to increased CO2 lessening; CO2 has increased 4 fold, temp 2 fold. Log decline proved.

cohenite,

you say: In this respect the log curve I linked to is not “vaguely reminiscent” of the log effect, it is exactly the log effect of extra CO2:

http://wattsupwiththat.files.wordpress.com/2010/03/co2_modtrans_img1.png

This curve may be exactly the effect of extra CO2 (according to someone's calculations or experiments). It's certainly not exactly a log curve.

Mr. Cox, I can only conclude you would not recognize a log if you tripped over one.

There was nothing about that graph that was logarithmic, not the axes, nor the data, nor the trend line.

There are no 6th order polynomial processes in physics. Even if there were, have you thought about what that function would look like if it was extrapolated outside the data? Obviously not. I will help you out, you can see one here http://www.analyzemath.com/polynomials/graph_polynomial_1.html Just scroll down to the 6th order graph.

The prediction from a 6th order polynomial is that in some relatively short period, the warming effect of CO2 is going to go through the roof. The predicted outcome from the curve presented by Viv Forbes is so bad that I suggest we should ban all CO2 emissions tomorrow to stop the world from frying.

You are such a chump Anthony.

It's like extracting teeth. Jeremy says:

"This curve may be exactly the effect of extra CO2 (according to someone's calculations or experiments). It's certainly not exactly a log curve."

What it is, is a graphical representation of how the RF from increased CO2 decreases at a logarithmic rate with increased CO2.

If you don't think it is that present your own Modtran graph and tell us what your graph is. After all you're the one who insists the IPCC has factored in the log decline to its climate sensitivity predictions.

Is this supposed to be a graph showing the forcing attributable to CO2?

If so, why does it start at 235 W/m^2 for 0 ppm CO2?

Dear Cohenite,

I am going to assume your offering - Posted by cohenite, Monday, 10 March 2014 11:29:17 AM – was in answer to my request for you to look at the graph I mentioned. If it is then thank you.

We all know the temperature figures on the graph are wrong as you acknowledged but that is not actually what I asked. I wanted to know how you thought he derived them. Forensics, that is where the fun lies, but as you said I should ask the author.

I am actually getting closer in determining how he came up with the original graph in his article. It should have been simple given he has supplied his data sets but I'm not there yet.

Anyway in answer to Bugsy's query you were indeed taking the piss and I am about to make a rare concession – in a contest between you and Mr Forbes as our resident anti-AGW spruiker you get my vote. He seems be the Anthony Cox of about 5 years ago. But don't let it go to your head.