Nick,
Don't blame heading out. I was the one who read that into the data. Thanks for the link. I have been wanting to read that paper. The NAS report actually delivers a gentle rebuke to Mann and the hockey stick crowd, since it says that it is only plausible (i.e. possible) that the late 20th century was warmer than the medieval warming, but the data are too weak to reach a firm conclusion.
There are a couple of reasons why Greenland data might show more warming than other regions. One is that climatologists generally assert that warming trends are magnified in extreme latitudes. (I forget the reference, but it was in a discussion of the likelihood of melting ice caps.) The second is that the best data is from Greenland with the ice cores.
As an old forester, the one thing I actually know a little about is dendrochronology. I am very skeptical about tree rings as a temperature proxy because there are too many other variables. When you are trying to construct a record more than 500 years old, the number of specimens is so small that efforts to filter out noise inevitably become very subjective.

You lost me with the last paragraph. Anyone who is even a little bit skeptical will start to become paranoid if you try to shut off the discussion. The politicians deciding what to do about these issues are typically people with a bachelor's degree and an IQ of 120-130. You won't make any points if you belittle their ability to understand the science.