The Difference between ‘True Science’ and ‘Cargo-Cult Science’
Don’t forget misusing data. In order to get the hockey stick shape he had to include the bristelcone pine series. The problem with that was the fact that the person who generated the series stated specifically that this data set was not a proxy for temperature. It is a much stronger proxy for precipitation. For a large number of reasons, tree rings can not be used a proxies for temperature. They are a proxy for the quality of the growing season, which includes many factors, only one of which is temperature. Additionally, trees do not have a linear response to changes in temperature, they have an inverted U shape curve. As temperature increases, all other things being constant (which they never are) growth will increase, up to a point, then as temperature gets above that point, growth decreases.
To get the hockey stick Mann had to both use bad statistics and bad data.
