Notso fantastic
Again, you raise some interesting points.
Addressing your points in turn:
>This is quite ignoring the heat energy within the earth, and how
>much is leaking to the surface.
Fair point, but it is easy to show that the amount of energy transfered to the surface from geothermal heat is trivial in comparison with the amount of energy coming in from the sun. Proof of this can be seen on the Antarctic continent, which has ice frozen to the bedrock across most of the land surface. If geothermal heat was so significant it would melt the bed.
>We all know it's pretty hot down there. The thing is, the earth is
> not constant, Ice Ages come and go, everything cycles.
True, ice ages are controlled by the Milankovic Cycles, which are associated with changes in the orbital characteristics of the Earth. The next Ice Age will come, pretty much regardless of what humans do, though we may delay it a little. But these changes occur on 100,000 year cycles (the last glacial maximum was c. 20,000 years ago, the last interglacial c. 100,000 years ago). The change we are seeing occurs on a much shorter timescale, and is occurring MUCH faster than any other change we can find in the geological record, except the extinction events (which is a warning in itself).
> As I see it, all the alleged pollution mankind produces is but a
> mere trifle compared to a resounding 'burp' from a damn good
> volcano
Yes, volcanoes have a big influence. But their impacts are a short burp, followed by a long period without burps. What we are doing is releasing a constant stream.
Taking CO2 for example, annual anthropogenic emissions are thought to be more than 150x the annualised emissions from volcanic sources (Gerlach 1991 if you want to know the source of this)
Taking sulphur, volcanic and other natural sources = 25 Tg / year. Human sources = 79 Tg (i.e 3x as much) (source = Andres and Kasgnoc 1997)
We can show that a big volcanic eruption does change climate (no-one denies this). If we are putting so much more into the atmosphere, isn't it logical that this will affect climate too?
> I have gone from being a member of Friends of the Earth and
> Greenpeace to totally regarding such organisations as 'political'
> and cynically against anything to do with 'progress'.
I can't argue with that! Doesn't change the reality of the science though.
DrDave