evidence: The image below shows a "hockey stick" temperature graph for the past 1000 years. This particular version is from the Summary for Policymakers of the IPCC’s third assessment report from 2001, and it applies only to the Northern Hemisphere. [...] If the results of this study are broadly correct, then pre-industrial temperature variability has been high, which would mean that hockey stick temperature graphs are not correct. [...] and that the use of [signal-free standardization] instead of traditional [negative exponential] chronologies results in an overestimation of recent temperature trends and a lack of reconstruction skill. [Emphasis added]