Science Magazine has good news for global warming crowd: The Hockey Stick is back!
It was shown to be a fraud before, but now -- Shazam!It's back!
Gee it's hot today. But... compared to what? That's the big question in the global warming game. The best ways of measuring world temps is with satellites and weather balloons, using space-age electronics. Which didn't exist until recently. So if it seems hotter today, we have to guess at the historic baseline for the last 2,000 years.
Or rather, we end up using "baseline surrogates." Like Arctic ice cores, tree rings, and such. Politicians do it all the time with job figures and the economy. Look how many jobs we didn't lose this quarter! It could have been a lot worse! They just make up a low baseline for comparison. Kids do the same thing when they come home with a bad report card. It could have been a lot worse, Mom!
Now the trouble with "surrogate baselines" for anything in science is that it takes a long time to figure out what they really mean. Is your cholesterol level really a good "baseline surrogate" for your chances of blowing a gasket down the line? Turns out it isn't that good. You can have low cholesterol and run into trouble in middle age, or high cholesterol and live to a ripe old age. With longitudinal measures (over long periods of time) we usually find out how good they are after a long time passes, to check the surrogate against real data. Until then we are just speculating. A huge amount of scientific debate is precisely about that question. It goes on all the time. It's only in the warming game that temperature surrogates are accepted without question. If they are low enough, so we can "prove" that things have gotten hot, hot.