Some very interesting points raised.
No one knows what the climate was of the earth pre recorded history. There is evidence to suggest that there were periods even during this last series of glacial/inter-glacial fluctuations that might have been warmer than today and certainly there is a strong presumption that there were periods prior to that that were warmer but actual temperatures are not known and the evidence is not planet wide for any period so supposition has to be used.
But I still find it amazing that we go through two prolonged periods of cooling in the twentieth century, a warming period of quite short duration and then from about 1980 another warming period (and using NASA's figures, that warming trend equates to 0.04 to 0.06 degrees per decade) and this somehow correlates with man's activities. Huh? That's a bit like saying that Hurricane Andrew was caused by man because of the rapidly increasing usage of land and sea in the area where Andrew struck.
Coincidences can a do occur in the natural world. To not be a coincidence you actually need some science that is not "herd mentality" to suggest otherwise.
Why was it cooling during much of the century when the greenhouse gases were already substantial from man's activities?
These are all philisophic questions that cannot easily be answered but they certainly deserve some considered thought.
