In a recent paper, McKitrick and Michaels (2004, or “MM04”) argue that non-climatic factors such as economic activity may contaminate climate station data, and thus, may render invalid any estimates of surface temperature trends derived from these data. They propose that surface temperature trends may be linked to various local economic factors, such as national coal consumption, income per capita, GPD growth rate, literacy rates, and whether or not temperature stations were located within the former Soviet Union. If their conclusions were correct, this would hold implications for the reliability of the modern surface temperature record, an important piece of evidence indicating 20th century surface warming. However, numerous flaws with their analysis, some of them absolutely fundamental, render their conclusions invalid.
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