Behind the Hockey Stick

Abstract

The article profiles climatologist Michael Mann and discusses his research regarding global climate changes. Mann is most famously known for the "hockey stick," a plot of the past millennium's temperature that shows the drastic influence of humans in the 20th century. That stick has become a focal point in the controversy surrounding climate change and what to do about it. To construct the hockey-stick plot, Mann, Raymond S. Bradley of the University of Massachusetts Amherst and Malcolm K. Hughes of the University of Arizona analyzed paleoclimatic data sets such as those from tree rings, ice cores and coral, joining historical data with thermometer readings from the recent past. A community skeptical of human-induced warming argued that Mann's data points were too sparse to constitute a true picture, or that his raw data were numerically suspicious, or that they could not reproduce his results with the data he had used. Although questions in the field abound about how, for example, tree-ring data are compiled, many of those attacking Mann's work have had a priori opinions that the work must be wrong. One of Mann's more public punch backs took place in July 2003, when he defended his views before a congressional committee led by Senator James M. Inhofe of Oklahoma, who has called global warming a "hoax." INSET: MICHAEL MANN, DETECTING PAST CLIMATE.