NZ Herald: Tree-ring anomaly mystifies scientists

Eloise Gibson of the NZ Herald reports that scientists are trying to explain an anomaly in tree-ring temperature data.

Tree-ring records are a good measure for temperature, at least until the 1950s.  Since then, however, there has been a divergence between what the tree rings say, and what recorded temperatures were.

An excerpt: (read in full here)

“But although researchers of ancient climate have several theories, so far no single theory can explain why some Northern Hemisphere trees behaved differently in the past few decades.

“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.”