The abstract:

No current tree ring (TR) based reconstruction of extratropical Northern Hemisphere (ENH) temperatures that extends into the 1990s captures the full range of late 20th century warming observed in the instrumental record. Over recent decades, a divergence between cooler reconstructed and warmer instrumental large-scale temperatures is observed. We hypothesize that this problem is partly related to the fact that some of the constituent chronologies used for previous reconstructions show divergence against local temperatures in the recent period. In this study, we compiled TR data and published local/regional reconstructions that show no divergence against local temperatures. These data have not been included in other large-scale temperature reconstructions. Utilizing this data set, we developed a new, completely independent reconstruction of ENH annual temperatures (1750–2000). This record is not meant to replace existing reconstructions but allows some degree of independent validation of these earlier studies as well as demonstrating that TR data can better model recent warming at large scales when careful selection of constituent chronologies is made at the local scale. Although the new series tracks the increase in ENH annual temperatures over the last few decades better than any existing reconstruction, it still slightly under predicts values in the post-1988 period. We finally discuss possible reasons why it is so difficult to model post-mid-1980s warming, provide some possible alternative approaches with regards to the instrumental target and detail several recommendations that should be followed in future large-scale reconstruction attempts that may result in more robust temperature estimates.

Wilson tries to address the divergence issue head on, he uses new proxies which do not diverge against local temperatures. He tries to follow the NAS guidelines, and comes up with a few of his own. He has archived the data. All of these seem commendable.

However, to me at least, it’s not surprising that you can find tree rings that match local recent temperature records, but how to be sure they match over the last 4-100 years?

McIntyre and McKitrick are cited neutrally.

#47 No, leave the math of A/C, brick and road cover to the GCM makers, because they’re not interested in accurate measurements, obviously.

10 SECONDS. that’s twice as long as you last.

Now, you’ve pumped twice and its all over.

Um, what’s going on here?

Leave the mathematics of air conditioners, brick walls and asphalt to the GCM makers.

You mean leave the science to the scientists?

I’ve no idea how to model compression and the phenomenon of false rings, but it just seemed interesting to me that the double dip of the LIA in the CET record appears stretched and shifted further back, as if extra rings had interposed themselves into the record of the 17th and 18th Centuries.

I’m not saying for definite, but its peculiar coincidence.

P.s. My 15 was in response to 14. I was not the first to raise the issue. However, I recognize, however, that when I make a contrary posting, that it has a more derailing impact than the off topic “skeptic view” post. I will try not to respond to such off topic comments.

The reason I think of this is the early part of Rob’s reconstruction (RCS method) looks a lot like the beginning of the Central England Temperature Record, except the “double-dip” appears almost 100 years later.

Try it Steve by plotting the two together and you’ll see what I mean.

I can only surmise that in the Little Ice Age, there were frequent unseasonal cold snaps that interrupted the growing season of many things.