An interesting article from the New Zealand Herald, looking at the divergence problem. What particularly fascinated me was the explanation of the issue from Andy Reisinger, who some will remember as being a man who is very close to Rajendra Pachauri.
Reisinger is a climatologist, but not, if I remember correctly, a paleo guy. It's odd then to see him being the expert interviewed on the subject of the divergence problem. It might also explain the explanation he gives for this inconvenient effect:
Dr Andy Reisinger, a climate researcher at Victoria University who has followed the progress of proxy temperature reconstructions, said it could be that a lack of rain in recent decades had stunted tree growth in some high-altitude spots - or that when temperatures reached a certain point, trees began to react differently.
Whatever the cause, "the relationships [between tree-rings and temperature] that we've developed for the last 500-100 years may not apply in the last 50," he said.
Now correct me if I'm wrong, but I thought that paleoclimatologists picked trees that were sensitive to temperature rather than precipitation when they set about recreating temperatures of the past. If a drop in rainfall can cause a drop in growth now, then it could have caused a drop in the past. In other words, the paleo guys will have to admit that they know absolutely nothing about temperatures before the nineteenth century.