From your post, "Unfortunately, our tools are too crude to reveal what man's effect has been in the past, let alone predict how much warming or cooling we might cause in the future."
Hard not to disagree with that statement. I was just trying to figure out how cold my freezer and refrigerator were - 3 different thermometers gave 3 different readings, with variations of several degrees. We've got climate scientists trying to quantify historical temperatures, taken at various places on earth, under varying conditions, with different thermometers of different makes, over a hundred years or more. No way can they pin it down to a degree or two. Yes, they've got satellite and other data, but I'd think that has to contain a large amount of theoretical rather than hard measurements.
And they are 'recording' temperatures thousands , millions of years ago? How?
Esp. when they claim 2 deg C. is a calamity.
I can understand their claiming an ancient period had slow growth, vis-a vis tree rings and such but nailing it down to a degree or two?? Hmmmmm
And of course there is the problem of their wanting a particular outcome. Schmooze the evidence?? You bet.
Create a crisis, get a gov. grant. $$$$$
At the outset, airports were generally located out in the open rural spaces...few, if any, buildings etc.
Then the airports became surrounded with houses, businesses and buildings in general. This produced the well-known city "heat island" effect and suddenly the archived temperature readings from these airports showed a definite upward trend.
This phenomenon invalidates a lot of so-called global warming via temperature records.