Hockey-stick artist Michael Mann is back, along with the rest of his team from Penn State’s Earth System Science Center, with his hockey stick, this time supported by more proxy data.
Although McIntyre and McKitrick had some valid criticisms of Mann's initial work, the National Academy of Sciences and others have essentially supported him, both with respect to the blade of the hockey stick and the longer-term handle.
Unlike Mann's initial paper, which was based on temperature reconstructions from tree-ring data, Mann's latest version of the "hockey stick" has been upgraded by a greatly expanded set of proxy data for decadal-to-centennial climate changes and recently updated instrumental data, and has been extended to cover temperatures in the Northern Hemisphere for the past 1,700 years.
The results? As the Christian Science Monitor notes:
And the graph illustrating the take-home message? It still looks a lot like the much-battered, but still rink-ready stick of 1998. Today the handle reaches further back and it’s a bit more gnarly. But the blade at the business end tells the same story.
The latest hockey stick paper appears in the Proceedings of the National Academy of Science (the revised hockey stick chart appears as Figure 3).
The relative sharpness of the hockey stick blade is even more apparent in a 10,000 year view of temperature changes.
A discussion of the relevance of the temperature reconstructions is here.