Hockey Stick? What Hockey Stick? - WEBCommentary

substance that is plant food. With sunlight, chlorophyll, and water, it is an essential ingredient in
plant photosynthesis, without which there would be little or no life on Earth.
Seen in a geological perspective, the pre-industrial concentration of carbon dioxide was almost as
low as it has been in the past half-billion years. Indeed, even the present concentration is well
below what has been the norm in recent geological history. In the Cambrian era, for instance, a
diagram in the IPCC’s 2001 assessment report shows that carbon dioxide concentration was almost
20 times that of today.
Tree-rings, therefore, were unsuitable because CO 2 fertilization distorted the data. The fabricators
of the “hockey stick” nevertheless gave the unreliable tree-rings 390 times as much weight as any
of the other data they used, because the tree-ring data, unlike the remaining paleoclimate data they
had used in fabricating the graph, gave them the hockey-stick shape they wanted.
This shape allowed them to do what David Deming had been told that the environmentalist faction
wanted to do – namely, to abolish the medieval warm period and pretend that today’s temperatures
were likely to have been unprecedented in the past 1000 years.
Tree-rings from Sheep Mountain, CA, that produced the desired “hockey-stick” shape, falsely suggesting a
pronounced uptrend in the 20 th century, (upper panel) were given 390 times more weight than tree-rings from
Mayberry Slough, AZ, that correctly suggested a far less dramatic picture (lower panel). The IPCC had
recommended against using tree-rings as the basis for reconstructing pre-instrumental surface temperatures
on Earth because not only warmer weather but also increased carbon dioxide concentration accelerates the
growth of trees and hence widens their annual growth-rings.
Not only did the fabricators of the “hockey stick” use temperature proxies that the IPCC had said
should not be used; not only did they give these questionable proxies almost 400 times more weight
than proxies that did not give them the hockey-stick shape they wanted; but they then also left out
the tree-ring dataset that included the medieval warm period itself.
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