MrSurrey said "Another angle for defence here (against global warming in general rather than aviation's contribution to it) that I didn't see on the website are the temperature fluctuations on other planets in our solar system. The fluctuations seemed to mirror Earth's temperature variations suggesting that changing sun activity is a major factor - can anyone lay their hands on the relevent statistics/graphs?"
The paper that has caused a stir on this recently is this one:
Hammel, H. B., and G. W. Lockwood, 2007. Suggestive correlations between the brightness of Neptune, solar variability, and Earth’s temperature, Geophysical Research Letters, 34, L08203, doi:10.1029/2006GL028764.
However, before anyone gets too excited, the authors state in the paper:
"An important caveat is that even for the well-studied Earth temperature variability, the steady rise in temperature since the mid 1970s is not fully understood, but has an anthropogenic component due in part or entirely to rising greenhouse gases, in combination with changes induced by sulfate and volcanic aerosols, and/or other forcing factors. Total solar irradiance seems to be ruled out as a driving factor in temperature variations, although other components of solar output may still play a role.