Rhetorical Analysis

On April 22, 1998, climate scientists Michael E. Mann, Raymond S. Bradley and Malcolm K. Hughes published an article that received unprecedented attention for a publication of its kind. In their initial piece “Global-Scale Temperature Patterns and Climate Forcing Over the Past Six Centuries,” the authors charted global annual surface temperature patterns for 600 years. As a response to significant interest within the scientific community, the next year they released a paper that reconstructed average temperatures over the entire past millennium. The result of their work is the graph below
The graph collapses the time scale of a millennium to show the drastic changes of industrialization. It incorporates thermometer temperature readings (the

oldest dating back to the mid 19th century) and data from proxy measurements (tree rings, ice cores, and historical records) reaching as far back as the eleventh century to create a linearized understanding of temperatures across time. In it we see a steady oscillation of temperatures with half a degree Celsius from the earliest data points until the 20th century, when the line following the measurements juts up aggressively. This ascension, the article explained, is coincident with rapid increases in atmospheric CO2 levels from fossil fuel burning since the dawn of the industrial revolution. Perhaps most importantly, the ascension itself provides a startling visual message that makes apparent a deep-lying problem that often goes unnoticed in our daily experiences. Its shape also gave it the name “hockey stick graph.” This dramatic visual potency is why it has survived to this day as a powerful symbol of human-induced climate change.