A quick search shows "Nick Brooks" first entry is:
http://www.cru.uea.ac.uk/~e118/welcome.htm

And briefly says member involve in Stern report.
In executive summary of Stern report:
"The current level or stock of greenhouse gases in the atmosphere is equivalent to around 430 parts per million (ppm) CO2, compared with only 280ppm before the
Industrial Revolution. These concentrations have already caused the world to warm by more than half a degree Celsius and will lead to at least a further half degree warming over the next few decades, because of the inertia in the climate system."

So I can assume from just this that you think all increase in global temperature is due to CO2 but further than this you assume that further warming is coming from this increase of CO2, so that accordingly I can assume my answer to my question of increase or decrease of 100 ppm Global would result in a increase or decrease about a 1 C.

Now, I don't agree with this, but I was interested in where you were coming from and I seemed to have got my answer. Can I assume you think Al Gore is accurate?
Can I further concluded that all the public needs as far as information is to show the Inconvenient Truth, to children who are seven year old?