Over the years, I've taken a passing interest in climate issues, not to a point of being able to claim expertise, but enough for me to consider the issue as a whole. My impression is that the studies of climate change tend to focus on the recent past, generally correlating with the industrial revolution, rather than focus on the more distant past, and as result it seems to me that conclusions are drawn on too narrow a set of data. This is not to say that there are not studies of the distant past, but rather that those don't appear to me to inform the discourse on this subject at the present time.
To give an example, towards the end of the last period of glaciation, about 12,000 years ago, the earth began to warm, but suddenly plunged back into bitter cold for a period known as the Younger Dryas. This lasted for about 1000 years, and towards the end of this time, the earth suddenly warmed by 4 degrees C in 25 years!! Nobody, as I understand it, claims to understand what might have caused this rapid warming through any natural phenomena, yet according to the record of the Greenland ice cores, it definitely occurred. This is just one example of variation that is not well understood, yet which must undeniably be ascribed to anything other than man's activities. Hence, it may be that today's warming may be nothing to do with Man.
When I add in the obvious fact that climate science is very much statistical in its approach, and relies on a great deal of interpretation for its conclusions, I find myself sceptical about the conclusions. This is not through any dogma on my part, but simply because I like scientific conclusions to be based on verifiable facts and the replicability of experiments to demonstrate a position, and this is simply not easy to do with climate science. My position, therefore, is that I don't deny the facts of climate change: increased CO2, sea temperatures and levels, glaciers melting etc. but I remain unconvinced that Man in his arrogance assumes it must be because of us.
Now stands back to await the brickbats!!