It's 75 Degrees in Sunny San Diego

If you want to know how warm it is outside, you look at the thermometer. That's a fact that has meaning. Forty-four degrees means something. Ninety-five degrees means something else.

But in the great Global Warming [movealongnothingtoseehere] Debate, I've always been troubled by trying to understand how one could possibly overcome the fact that, for example, National Airport (the official weather measuring point for Washington, D.C.), was in the middle of nowhere 50 years ago, but is today surrounded by development. Surely that has a great effect on the temperatures recorded there. And how the heck do we know (and within a few degrees) what the temperature was at this particular bend of the Patawomeke River (as John Smith's map had it) in 1650?

Even worse: What does "global temperature" mean? Apparently, it doesn't mean hardly anything useful.