This is so good, I just had to nick a copy for posterity:

“Ian McFadyen:

24 Apr 2008 9:51:15pm

As a skeptic, denier, contrarian, delusionist of what ever you want to call me, I’m happy to tell you what I think.

The climate change question is not one question but three.

1. Is the world getting warmer?
   
2. Is it because of human activity?
   
3. Will the warming cause a disaster for humans?
   

My answers are as follows.

One: we don’t know if the world is getting warmer. Why not? Because we can NEVER know if the world - or anything else - is getting warmer. We can only know if it HAS warmed. It is something we can only measure AFTER the event, not during and certainly not BEFORE. Some scientists claim that the correlation between CO2 and temperature has been established and therefore as CO2 increases, temperatures must increase but correlations do NOT prove causality and even if there is such a causal relationshop, the effects relationship cannot be predicted by simple extrapolation because climate is a chaotic system with many unknown factors, feedback loops, homeostatic controls and butterfly effects. The warming predictors are putting forward a hypothesis that the world will get warmer, and then claiming that the hypothesis has been confirmed BEFORE it has been tested. This is not science.

Second. even if the world has been getting significantly, and I stress significantly warmer, (the increase in temperatures over the 20th century has been in the order of 1/500th), we cannot know if it is because of human activity. Again, not “do not” but “cannot”. Because we do not have a Control - i.e. planet that is identical to Earth but with no humans we can never isolate the human factor from all the others. There is simply no statistical way to separate the human from the natural factors - especially since we don’t even know all the natural factors yet.

Three: even if the world IS getting warmer, why might the benefits not be equal to or greater than the problems. e.g. longer growing seasons in high latitudes, less need for heating fuel in cold climates, permanent sea access around Canada, more rain in desert areas etc. Given all these uknowns, some of which are unknowables, the assurance and dogmatism of many climate scientists is a betrayal of the scientific method and represents not real scientific rigour but conjecture, hypothesising and perhaps even wishful thinking.”

Thanks to Pogria for doing the original copying from the ABC (no link).