Does it matter if we use PMOD or ACRIM for the TSI?

Question

An interesting discussion here:

http://tamino.wordpress.com/2007/07/24/pmod-vs-acrim/

Using ACRIM concludes:

"A better idea would be to fit a trend line to the residuals, which yields a slope of 0.01 W/m^2/yr, or 0.1 W/m^2/decade...If that trend were sustained throughout the 28-year duration of the data, it would lead to a net secular increase in TSI of 0.31 W/m^2, which would cause an increase in climate forcing of 0.076 W/m^2. That’s only marginally bigger than the climate forcing due to anthropogenic power generation. At a climate sensitivity of 0.75 deg.C/(W/m^2), it would lead to a net global temperature rise of 0.06 deg.C, far smaller than what is observed. Even using the ACRIM composite, satellite estimates of TSI will not support the idea that TSI changes are responsible for modern global warming."

Does anyone dispute the conclusion that neither TSI (total solar irradiance) composite can account for a significant fraction of the recent climate forcing?

Tomcat - you've argued that it does matter, but I don't see how you can make the argument. "Physics is physics" doesn't exactly explain anything.

Ben O - that simply explains why it's important to examine the TSI trend rather than placing importance on the 11-year cycle. The TSI trend has changed little in the past 50 years.

I want people to answer the question, Ben. You did not. At least Tomcat made an effort.

Answer 1

You know my position on the subject, physics are physics.

EDIT:

Dana you have to actually look at the data, if you do you will see that the ACRIM composite from 1992 until present has at least .5 WM^2 more output, especially in the solar minimum before cycle 23. PMOD during that period cools down by almost .75 watts lower for several years. Are saying that the Earth would not be warmer if the Sun output more energy?

I don't really feel the need to go into the spectral analysis debate about the conclusions of Scafetta & West, been there and done that. And as far climate sensistivity parameters, we are talking about the root source of climate here. If the Sun outputs more energy for several years naturally the Earth will be warmer, the oceans will absorb more energy, the atmosphere will maintain more water vapor and there will be less surface ice and there may well be other positive feedback mechanisms. None of these are factored into the 35% figure as far as the ACRIM composite.

So if two pots of water are placed on separate burners in which the temperature is maintained on one burner at a slightly elevated level (ACRIM), it will be warmer, physics prevails, regardless of what climate sensitivity parameters you use.
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Answer 2

The author of that web page seems to think that you should multiply the TSI increase by .25 then by .7 (to allow for the Earths albedo) to get climate forcing.

The author also points out that the .75 degrees per (W/m^2) temperature change takes a period of time to be occur (but doesn't quantify what the time response characteristic could be). If the temperature takes a long time to realise the effects of a change in solar intensity, then the rate of change of temperature attributable to solar intensity would partly depend on changes that occurred in STI a 'long time' ago.

You should probably look at how the time lag effects your calculation.

(edit) If you only want people who agree with you to answer, you should put that in your question.