[zosi]

Hmm, it looks like the first link got eaten by HN's linkerator due to the %27 (single quote) in the URL. Sorry about that, try http://preview.tinyurl.com/ydb8h28.

As for the calibration period, you're right, there are definitely some issues there, and that's a problem with the entire temperature reconstruction approach. We only have reliable instrumental records back to the middle of the 19th century, so it's hard to test any kind of reconstruction on a large scale.

Personally, I don't put much faith in the reconstructions themselves - I just think that it's important for people to understand the context around these experiments, since there's so much blatantly false information going around. It's hard enough for those of us who aren't climatologists to keep up with the information without people screaming bloody murder over a few lines of comments that they don't even understand.